From 495d2d8133fd1407519170a5238f455abbd9ec9b Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 26 Dec 2023 11:11:43 -0800 Subject: [PATCH 1/6] selftests/bpf: Attempt to build BPF programs with -Wsign-compare GCC's -Wall includes -Wsign-compare while clang does not. Since BPF programs are built with clang we need to add this flag explicitly to catch problematic comparisons like: int i = -1; unsigned int j = 1; if (i < j) // this is false. long i = -1; unsigned int j = 1; if (i < j) // this is true. C standard for reference: - If either operand is unsigned long the other shall be converted to unsigned long. - Otherwise, if one operand is a long int and the other unsigned int, then if a long int can represent all the values of an unsigned int, the unsigned int shall be converted to a long int; otherwise both operands shall be converted to unsigned long int. - Otherwise, if either operand is long, the other shall be converted to long. - Otherwise, if either operand is unsigned, the other shall be converted to unsigned. Unfortunately clang's -Wsign-compare is very noisy. It complains about (s32)a == (u32)b which is safe and doen't have surprising behavior. This patch fixes some of the issues. It needs a follow up to fix the rest. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Jiri Olsa Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/bpf/20231226191148.48536-2-alexei.starovoitov@gmail.com --- tools/testing/selftests/bpf/Makefile | 1 + .../selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c | 2 +- tools/testing/selftests/bpf/progs/bpf_iter_task_vmas.c | 2 +- tools/testing/selftests/bpf/progs/bpf_iter_tasks.c | 2 +- tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c | 2 +- .../selftests/bpf/progs/cgroup_getset_retval_setsockopt.c | 2 +- tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c | 2 +- tools/testing/selftests/bpf/progs/cpumask_success.c | 2 +- tools/testing/selftests/bpf/progs/iters.c | 4 ++-- tools/testing/selftests/bpf/progs/linked_funcs1.c | 2 +- tools/testing/selftests/bpf/progs/linked_funcs2.c | 2 +- tools/testing/selftests/bpf/progs/linked_list.c | 2 +- tools/testing/selftests/bpf/progs/local_storage.c | 2 +- tools/testing/selftests/bpf/progs/lsm.c | 2 +- tools/testing/selftests/bpf/progs/normal_map_btf.c | 2 +- tools/testing/selftests/bpf/progs/profiler.inc.h | 4 ++-- tools/testing/selftests/bpf/progs/sockopt_inherit.c | 2 +- tools/testing/selftests/bpf/progs/sockopt_multi.c | 2 +- tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c | 2 +- tools/testing/selftests/bpf/progs/test_bpf_ma.c | 2 +- .../testing/selftests/bpf/progs/test_core_reloc_kernel.c | 2 +- .../testing/selftests/bpf/progs/test_core_reloc_module.c | 8 ++++---- tools/testing/selftests/bpf/progs/test_fsverity.c | 2 +- tools/testing/selftests/bpf/progs/test_skc_to_unix_sock.c | 2 +- tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c | 2 +- 25 files changed, 30 insertions(+), 29 deletions(-) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 617ae55c3bb5b..fd15017ed3b12 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -383,6 +383,7 @@ CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH)) BPF_CFLAGS = -g -Wall -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) \ -I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR) \ -I$(abspath $(OUTPUT)/../usr/include) +# TODO: enable me -Wsign-compare CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \ -Wno-compare-distinct-pointer-types diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c index feaaa2b89c574..5014a17d6c02f 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c +++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c @@ -20,7 +20,7 @@ struct { } hashmap1 SEC(".maps"); /* will set before prog run */ -volatile const __u32 num_cpus = 0; +volatile const __s32 num_cpus = 0; /* will collect results during prog run */ __u32 key_sum_a = 0, key_sum_b = 0, key_sum_c = 0; diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_vmas.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_vmas.c index dd923dc637d5c..423b39e60b6f1 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter_task_vmas.c +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_vmas.c @@ -35,7 +35,7 @@ SEC("iter/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx) return 0; file = vma->vm_file; - if (task->tgid != pid) { + if (task->tgid != (pid_t)pid) { if (one_task) one_task_error = 1; return 0; diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c b/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c index 96131b9a1caae..6cbb3393f2438 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c +++ b/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c @@ -22,7 +22,7 @@ int dump_task(struct bpf_iter__task *ctx) return 0; } - if (task->pid != tid) + if (task->pid != (pid_t)tid) num_unknown_tid++; else num_known_tid++; diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c index 400fdf8d62332..dbf61c44acac6 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c +++ b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c @@ -45,7 +45,7 @@ int dump_bpf_map(struct bpf_iter__bpf_map *ctx) } /* fill seq_file buffer */ - for (i = 0; i < print_len; i++) + for (i = 0; i < (int)print_len; i++) bpf_seq_write(seq, &seq_num, sizeof(seq_num)); return ret; diff --git a/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c b/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c index b7fa8804e19de..45a0e9f492a97 100644 --- a/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c +++ b/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c @@ -11,7 +11,7 @@ __u32 invocations = 0; __u32 assertion_error = 0; __u32 retval_value = 0; -__u32 page_size = 0; +__s32 page_size = 0; SEC("cgroup/setsockopt") int get_retval(struct bpf_sockopt *ctx) diff --git a/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c b/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c index facedd8b82500..5e282c16eadc5 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c +++ b/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c @@ -15,7 +15,7 @@ struct { __type(value, long); } map_a SEC(".maps"); -__u32 target_pid; +__s32 target_pid; __u64 cgroup_id; int target_hid; bool is_cgroup1; diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c index fc3666edf4561..7a1e64c6c065c 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_success.c +++ b/tools/testing/selftests/bpf/progs/cpumask_success.c @@ -332,7 +332,7 @@ SEC("tp_btf/task_newtask") int BPF_PROG(test_copy_any_anyand, struct task_struct *task, u64 clone_flags) { struct bpf_cpumask *mask1, *mask2, *dst1, *dst2; - u32 cpu; + int cpu; if (!is_test_task()) return 0; diff --git a/tools/testing/selftests/bpf/progs/iters.c b/tools/testing/selftests/bpf/progs/iters.c index 3aca3dc145b55..fe971992e6359 100644 --- a/tools/testing/selftests/bpf/progs/iters.c +++ b/tools/testing/selftests/bpf/progs/iters.c @@ -6,7 +6,7 @@ #include #include "bpf_misc.h" -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +#define ARRAY_SIZE(x) (int)(sizeof(x) / sizeof((x)[0])) static volatile int zero = 0; @@ -676,7 +676,7 @@ static __noinline int sum(struct bpf_iter_num *it, int *arr, __u32 n) while ((t = bpf_iter_num_next(it))) { i = *t; - if (i >= n) + if ((__u32)i >= n) break; sum += arr[i]; } diff --git a/tools/testing/selftests/bpf/progs/linked_funcs1.c b/tools/testing/selftests/bpf/progs/linked_funcs1.c index c4b49ceea967b..cc79dddac182c 100644 --- a/tools/testing/selftests/bpf/progs/linked_funcs1.c +++ b/tools/testing/selftests/bpf/progs/linked_funcs1.c @@ -8,7 +8,7 @@ #include "bpf_misc.h" /* weak and shared between two files */ -const volatile int my_tid __weak; +const volatile __u32 my_tid __weak; long syscall_id __weak; int output_val1; diff --git a/tools/testing/selftests/bpf/progs/linked_funcs2.c b/tools/testing/selftests/bpf/progs/linked_funcs2.c index 013ff0645f0cc..942cc5526ddf0 100644 --- a/tools/testing/selftests/bpf/progs/linked_funcs2.c +++ b/tools/testing/selftests/bpf/progs/linked_funcs2.c @@ -68,7 +68,7 @@ int BPF_PROG(handler2, struct pt_regs *regs, long id) { static volatile int whatever; - if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id) + if (my_tid != (s32)bpf_get_current_pid_tgid() || id != syscall_id) return 0; /* make sure we have CO-RE relocations in main program */ diff --git a/tools/testing/selftests/bpf/progs/linked_list.c b/tools/testing/selftests/bpf/progs/linked_list.c index 84d1777a9e6c9..26205ca806796 100644 --- a/tools/testing/selftests/bpf/progs/linked_list.c +++ b/tools/testing/selftests/bpf/progs/linked_list.c @@ -6,7 +6,7 @@ #include "bpf_experimental.h" #ifndef ARRAY_SIZE -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +#define ARRAY_SIZE(x) (int)(sizeof(x) / sizeof((x)[0])) #endif #include "linked_list.h" diff --git a/tools/testing/selftests/bpf/progs/local_storage.c b/tools/testing/selftests/bpf/progs/local_storage.c index bc8ea56671a16..e5e3a8b8dd075 100644 --- a/tools/testing/selftests/bpf/progs/local_storage.c +++ b/tools/testing/selftests/bpf/progs/local_storage.c @@ -13,7 +13,7 @@ char _license[] SEC("license") = "GPL"; #define DUMMY_STORAGE_VALUE 0xdeadbeef -int monitored_pid = 0; +__u32 monitored_pid = 0; int inode_storage_result = -1; int sk_storage_result = -1; int task_storage_result = -1; diff --git a/tools/testing/selftests/bpf/progs/lsm.c b/tools/testing/selftests/bpf/progs/lsm.c index fadfdd98707c4..0c13b7409947e 100644 --- a/tools/testing/selftests/bpf/progs/lsm.c +++ b/tools/testing/selftests/bpf/progs/lsm.c @@ -92,7 +92,7 @@ int BPF_PROG(test_int_hook, struct vm_area_struct *vma, if (ret != 0) return ret; - __u32 pid = bpf_get_current_pid_tgid() >> 32; + __s32 pid = bpf_get_current_pid_tgid() >> 32; int is_stack = 0; is_stack = (vma->vm_start <= vma->vm_mm->start_stack && diff --git a/tools/testing/selftests/bpf/progs/normal_map_btf.c b/tools/testing/selftests/bpf/progs/normal_map_btf.c index 66cde82aa86d9..a45c9299552c9 100644 --- a/tools/testing/selftests/bpf/progs/normal_map_btf.c +++ b/tools/testing/selftests/bpf/progs/normal_map_btf.c @@ -36,7 +36,7 @@ int add_to_list_in_array(void *ctx) struct node_data *new; int zero = 0; - if (done || (u32)bpf_get_current_pid_tgid() != pid) + if (done || (int)bpf_get_current_pid_tgid() != pid) return 0; value = bpf_map_lookup_elem(&array, &zero); diff --git a/tools/testing/selftests/bpf/progs/profiler.inc.h b/tools/testing/selftests/bpf/progs/profiler.inc.h index 897061930cb76..ba99d17dac544 100644 --- a/tools/testing/selftests/bpf/progs/profiler.inc.h +++ b/tools/testing/selftests/bpf/progs/profiler.inc.h @@ -132,7 +132,7 @@ struct { } disallowed_exec_inodes SEC(".maps"); #ifndef ARRAY_SIZE -#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0])) +#define ARRAY_SIZE(arr) (int)(sizeof(arr) / sizeof(arr[0])) #endif static INLINE bool IS_ERR(const void* ptr) @@ -645,7 +645,7 @@ int raw_tracepoint__sched_process_exit(void* ctx) for (int i = 0; i < ARRAY_SIZE(arr_struct->array); i++) { struct var_kill_data_t* past_kill_data = &arr_struct->array[i]; - if (past_kill_data != NULL && past_kill_data->kill_target_pid == tpid) { + if (past_kill_data != NULL && past_kill_data->kill_target_pid == (pid_t)tpid) { bpf_probe_read_kernel(kill_data, sizeof(*past_kill_data), past_kill_data); void* payload = kill_data->payload; diff --git a/tools/testing/selftests/bpf/progs/sockopt_inherit.c b/tools/testing/selftests/bpf/progs/sockopt_inherit.c index c8f59caa46394..a3434b8409281 100644 --- a/tools/testing/selftests/bpf/progs/sockopt_inherit.c +++ b/tools/testing/selftests/bpf/progs/sockopt_inherit.c @@ -9,7 +9,7 @@ char _license[] SEC("license") = "GPL"; #define CUSTOM_INHERIT2 1 #define CUSTOM_LISTENER 2 -__u32 page_size = 0; +__s32 page_size = 0; struct sockopt_inherit { __u8 val; diff --git a/tools/testing/selftests/bpf/progs/sockopt_multi.c b/tools/testing/selftests/bpf/progs/sockopt_multi.c index 96f29fce050bc..db67278e12d4d 100644 --- a/tools/testing/selftests/bpf/progs/sockopt_multi.c +++ b/tools/testing/selftests/bpf/progs/sockopt_multi.c @@ -5,7 +5,7 @@ char _license[] SEC("license") = "GPL"; -__u32 page_size = 0; +__s32 page_size = 0; SEC("cgroup/getsockopt") int _getsockopt_child(struct bpf_sockopt *ctx) diff --git a/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c b/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c index dbe235ede7f38..83753b00a5569 100644 --- a/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c +++ b/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c @@ -9,7 +9,7 @@ char _license[] SEC("license") = "GPL"; -__u32 page_size = 0; +__s32 page_size = 0; SEC("cgroup/setsockopt") int sockopt_qos_to_cc(struct bpf_sockopt *ctx) diff --git a/tools/testing/selftests/bpf/progs/test_bpf_ma.c b/tools/testing/selftests/bpf/progs/test_bpf_ma.c index 069db9085e789..b78f4f702ae0f 100644 --- a/tools/testing/selftests/bpf/progs/test_bpf_ma.c +++ b/tools/testing/selftests/bpf/progs/test_bpf_ma.c @@ -21,7 +21,7 @@ const unsigned int data_sizes[] = {16, 32, 64, 96, 128, 192, 256, 512, 1024, 204 const volatile unsigned int data_btf_ids[ARRAY_SIZE(data_sizes)] = {}; int err = 0; -int pid = 0; +u32 pid = 0; #define DEFINE_ARRAY_WITH_KPTR(_size) \ struct bin_data_##_size { \ diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c index a17dd83eae674..ee4a601dcb066 100644 --- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c @@ -53,7 +53,7 @@ int test_core_kernel(void *ctx) struct task_struct *task = (void *)bpf_get_current_task(); struct core_reloc_kernel_output *out = (void *)&data.out; uint64_t pid_tgid = bpf_get_current_pid_tgid(); - uint32_t real_tgid = (uint32_t)pid_tgid; + int32_t real_tgid = (int32_t)pid_tgid; int pid, tgid; if (data.my_pid_tgid != pid_tgid) diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_module.c b/tools/testing/selftests/bpf/progs/test_core_reloc_module.c index f59f175c7bafb..bcb31ff92dccc 100644 --- a/tools/testing/selftests/bpf/progs/test_core_reloc_module.c +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_module.c @@ -43,8 +43,8 @@ int BPF_PROG(test_core_module_probed, #if __has_builtin(__builtin_preserve_enum_value) struct core_reloc_module_output *out = (void *)&data.out; __u64 pid_tgid = bpf_get_current_pid_tgid(); - __u32 real_tgid = (__u32)(pid_tgid >> 32); - __u32 real_pid = (__u32)pid_tgid; + __s32 real_tgid = (__s32)(pid_tgid >> 32); + __s32 real_pid = (__s32)pid_tgid; if (data.my_pid_tgid != pid_tgid) return 0; @@ -77,8 +77,8 @@ int BPF_PROG(test_core_module_direct, #if __has_builtin(__builtin_preserve_enum_value) struct core_reloc_module_output *out = (void *)&data.out; __u64 pid_tgid = bpf_get_current_pid_tgid(); - __u32 real_tgid = (__u32)(pid_tgid >> 32); - __u32 real_pid = (__u32)pid_tgid; + __s32 real_tgid = (__s32)(pid_tgid >> 32); + __s32 real_pid = (__s32)pid_tgid; if (data.my_pid_tgid != pid_tgid) return 0; diff --git a/tools/testing/selftests/bpf/progs/test_fsverity.c b/tools/testing/selftests/bpf/progs/test_fsverity.c index 3975495b75c8d..9e0f73e8189ce 100644 --- a/tools/testing/selftests/bpf/progs/test_fsverity.c +++ b/tools/testing/selftests/bpf/progs/test_fsverity.c @@ -38,7 +38,7 @@ int BPF_PROG(test_file_open, struct file *f) return 0; got_fsverity = 1; - for (i = 0; i < sizeof(digest); i++) { + for (i = 0; i < (int)sizeof(digest); i++) { if (digest[i] != expected_digest[i]) return 0; } diff --git a/tools/testing/selftests/bpf/progs/test_skc_to_unix_sock.c b/tools/testing/selftests/bpf/progs/test_skc_to_unix_sock.c index eacda9fe07ebb..4cfa42aa94361 100644 --- a/tools/testing/selftests/bpf/progs/test_skc_to_unix_sock.c +++ b/tools/testing/selftests/bpf/progs/test_skc_to_unix_sock.c @@ -29,7 +29,7 @@ int BPF_PROG(unix_listen, struct socket *sock, int backlog) len = unix_sk->addr->len - sizeof(short); path[0] = '@'; for (i = 1; i < len; i++) { - if (i >= sizeof(struct sockaddr_un)) + if (i >= (int)sizeof(struct sockaddr_un)) break; path[i] = unix_sk->addr->name->sun_path[i]; diff --git a/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c b/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c index 5baaafed0d2de..3abf068b84464 100644 --- a/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c +++ b/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c @@ -38,7 +38,7 @@ int xdp_redirect(struct xdp_md *xdp) if (payload + 1 > data_end) return XDP_ABORTED; - if (xdp->ingress_ifindex != ifindex_in) + if (xdp->ingress_ifindex != (__u32)ifindex_in) return XDP_ABORTED; if (metadata + 1 > data) From a8b242d77bd72556b7a9d8be779f7d27b95ba73c Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 26 Dec 2023 11:11:44 -0800 Subject: [PATCH 2/6] bpf: Introduce "volatile compare" macros Compilers optimize conditional operators at will, but often bpf programmers want to force compilers to keep the same operator in asm as it's written in C. Introduce bpf_cmp_likely/unlikely(var1, conditional_op, var2) macros that can be used as: - if (seen >= 1000) + if (bpf_cmp_unlikely(seen, >=, 1000)) The macros take advantage of BPF assembly that is C like. The macros check the sign of variable 'seen' and emits either signed or unsigned compare. For example: int a; bpf_cmp_unlikely(a, >, 0) will be translated to 'if rX s> 0 goto' in BPF assembly. unsigned int a; bpf_cmp_unlikely(a, >, 0) will be translated to 'if rX > 0 goto' in BPF assembly. C type conversions coupled with comparison operator are tricky. int i = -1; unsigned int j = 1; if (i < j) // this is false. long i = -1; unsigned int j = 1; if (i < j) // this is true. Make sure BPF program is compiled with -Wsign-compare then the macros will catch the mistake. The macros check LHS (left hand side) only to figure out the sign of compare. 'if 0 < rX goto' is not allowed in the assembly, so the users have to use a variable on LHS anyway. The patch updates few tests to demonstrate the use of the macros. The macro allows to use BPF_JSET in C code, since LLVM doesn't generate it at present. For example: if (i & j) compiles into r0 &= r1; if r0 == 0 goto while if (bpf_cmp_unlikely(i, &, j)) compiles into if r0 & r1 goto Note that the macros has to be careful with RHS assembly predicate. Since: u64 __rhs = 1ull << 42; asm goto("if r0 < %[rhs] goto +1" :: [rhs] "ri" (__rhs)); LLVM will silently truncate 64-bit constant into s32 imm. Note that [lhs] "r"((short)LHS) the type cast is a workaround for LLVM issue. When LHS is exactly 32-bit LLVM emits redundant <<=32, >>=32 to zero upper 32-bits. When LHS is 64 or 16 or 8-bit variable there are no shifts. When LHS is 32-bit the (u64) cast doesn't help. Hence use (short) cast. It does _not_ truncate the variable before it's assigned to a register. Traditional likely()/unlikely() macros that use __builtin_expect(!!(x), 1 or 0) have no effect on these macros, hence macros implement the logic manually. bpf_cmp_unlikely() macro preserves compare operator as-is while bpf_cmp_likely() macro flips the compare. Consider two cases: A. for() { if (foo >= 10) { bar += foo; } other code; } B. for() { if (foo >= 10) break; other code; } It's ok to use either bpf_cmp_likely or bpf_cmp_unlikely macros in both cases, but consider that 'break' is effectively 'goto out_of_the_loop'. Hence it's better to use bpf_cmp_unlikely in the B case. While 'bar += foo' is better to keep as 'fallthrough' == likely code path in the A case. When it's written as: A. for() { if (bpf_cmp_likely(foo, >=, 10)) { bar += foo; } other code; } B. for() { if (bpf_cmp_unlikely(foo, >=, 10)) break; other code; } The assembly will look like: A. for() { if r1 < 10 goto L1; bar += foo; L1: other code; } B. for() { if r1 >= 10 goto L2; other code; } L2: The bpf_cmp_likely vs bpf_cmp_unlikely changes basic block layout, hence it will greatly influence the verification process. The number of processed instructions will be different, since the verifier walks the fallthrough first. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Daniel Borkmann Acked-by: Jiri Olsa Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/bpf/20231226191148.48536-3-alexei.starovoitov@gmail.com --- .../testing/selftests/bpf/bpf_experimental.h | 69 +++++++++++++++++++ .../testing/selftests/bpf/progs/exceptions.c | 20 +++--- .../selftests/bpf/progs/iters_task_vma.c | 3 +- 3 files changed, 80 insertions(+), 12 deletions(-) diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 1386baf9ae4ad..19ed6c941c1c4 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -254,6 +254,75 @@ extern void bpf_throw(u64 cookie) __ksym; } \ }) +#define __cmp_cannot_be_signed(x) \ + __builtin_strcmp(#x, "==") == 0 || __builtin_strcmp(#x, "!=") == 0 || \ + __builtin_strcmp(#x, "&") == 0 + +#define __is_signed_type(type) (((type)(-1)) < (type)1) + +#define __bpf_cmp(LHS, OP, SIGN, PRED, RHS, DEFAULT) \ + ({ \ + __label__ l_true; \ + bool ret = DEFAULT; \ + asm volatile goto("if %[lhs] " SIGN #OP " %[rhs] goto %l[l_true]" \ + :: [lhs] "r"((short)LHS), [rhs] PRED (RHS) :: l_true); \ + ret = !DEFAULT; \ +l_true: \ + ret; \ + }) + +/* C type conversions coupled with comparison operator are tricky. + * Make sure BPF program is compiled with -Wsign-compare then + * __lhs OP __rhs below will catch the mistake. + * Be aware that we check only __lhs to figure out the sign of compare. + */ +#define _bpf_cmp(LHS, OP, RHS, NOFLIP) \ + ({ \ + typeof(LHS) __lhs = (LHS); \ + typeof(RHS) __rhs = (RHS); \ + bool ret; \ + _Static_assert(sizeof(&(LHS)), "1st argument must be an lvalue expression"); \ + (void)(__lhs OP __rhs); \ + if (__cmp_cannot_be_signed(OP) || !__is_signed_type(typeof(__lhs))) { \ + if (sizeof(__rhs) == 8) \ + ret = __bpf_cmp(__lhs, OP, "", "r", __rhs, NOFLIP); \ + else \ + ret = __bpf_cmp(__lhs, OP, "", "i", __rhs, NOFLIP); \ + } else { \ + if (sizeof(__rhs) == 8) \ + ret = __bpf_cmp(__lhs, OP, "s", "r", __rhs, NOFLIP); \ + else \ + ret = __bpf_cmp(__lhs, OP, "s", "i", __rhs, NOFLIP); \ + } \ + ret; \ + }) + +#ifndef bpf_cmp_unlikely +#define bpf_cmp_unlikely(LHS, OP, RHS) _bpf_cmp(LHS, OP, RHS, true) +#endif + +#ifndef bpf_cmp_likely +#define bpf_cmp_likely(LHS, OP, RHS) \ + ({ \ + bool ret; \ + if (__builtin_strcmp(#OP, "==") == 0) \ + ret = _bpf_cmp(LHS, !=, RHS, false); \ + else if (__builtin_strcmp(#OP, "!=") == 0) \ + ret = _bpf_cmp(LHS, ==, RHS, false); \ + else if (__builtin_strcmp(#OP, "<=") == 0) \ + ret = _bpf_cmp(LHS, >, RHS, false); \ + else if (__builtin_strcmp(#OP, "<") == 0) \ + ret = _bpf_cmp(LHS, >=, RHS, false); \ + else if (__builtin_strcmp(#OP, ">") == 0) \ + ret = _bpf_cmp(LHS, <=, RHS, false); \ + else if (__builtin_strcmp(#OP, ">=") == 0) \ + ret = _bpf_cmp(LHS, <, RHS, false); \ + else \ + (void) "bug"; \ + ret; \ + }) +#endif + /* Description * Assert that a conditional expression is true. * Returns diff --git a/tools/testing/selftests/bpf/progs/exceptions.c b/tools/testing/selftests/bpf/progs/exceptions.c index 2811ee842b01e..f09cd14d8e040 100644 --- a/tools/testing/selftests/bpf/progs/exceptions.c +++ b/tools/testing/selftests/bpf/progs/exceptions.c @@ -210,7 +210,7 @@ __noinline int assert_zero_gfunc(u64 c) { volatile u64 cookie = c; - bpf_assert_eq(cookie, 0); + bpf_assert(bpf_cmp_unlikely(cookie, ==, 0)); return 0; } @@ -218,7 +218,7 @@ __noinline int assert_neg_gfunc(s64 c) { volatile s64 cookie = c; - bpf_assert_lt(cookie, 0); + bpf_assert(bpf_cmp_unlikely(cookie, <, 0)); return 0; } @@ -226,7 +226,7 @@ __noinline int assert_pos_gfunc(s64 c) { volatile s64 cookie = c; - bpf_assert_gt(cookie, 0); + bpf_assert(bpf_cmp_unlikely(cookie, >, 0)); return 0; } @@ -234,7 +234,7 @@ __noinline int assert_negeq_gfunc(s64 c) { volatile s64 cookie = c; - bpf_assert_le(cookie, -1); + bpf_assert(bpf_cmp_unlikely(cookie, <=, -1)); return 0; } @@ -242,7 +242,7 @@ __noinline int assert_poseq_gfunc(s64 c) { volatile s64 cookie = c; - bpf_assert_ge(cookie, 1); + bpf_assert(bpf_cmp_unlikely(cookie, >=, 1)); return 0; } @@ -258,7 +258,7 @@ __noinline int assert_zero_gfunc_with(u64 c) { volatile u64 cookie = c; - bpf_assert_eq_with(cookie, 0, cookie + 100); + bpf_assert_with(bpf_cmp_unlikely(cookie, ==, 0), cookie + 100); return 0; } @@ -266,7 +266,7 @@ __noinline int assert_neg_gfunc_with(s64 c) { volatile s64 cookie = c; - bpf_assert_lt_with(cookie, 0, cookie + 100); + bpf_assert_with(bpf_cmp_unlikely(cookie, <, 0), cookie + 100); return 0; } @@ -274,7 +274,7 @@ __noinline int assert_pos_gfunc_with(s64 c) { volatile s64 cookie = c; - bpf_assert_gt_with(cookie, 0, cookie + 100); + bpf_assert_with(bpf_cmp_unlikely(cookie, >, 0), cookie + 100); return 0; } @@ -282,7 +282,7 @@ __noinline int assert_negeq_gfunc_with(s64 c) { volatile s64 cookie = c; - bpf_assert_le_with(cookie, -1, cookie + 100); + bpf_assert_with(bpf_cmp_unlikely(cookie, <=, -1), cookie + 100); return 0; } @@ -290,7 +290,7 @@ __noinline int assert_poseq_gfunc_with(s64 c) { volatile s64 cookie = c; - bpf_assert_ge_with(cookie, 1, cookie + 100); + bpf_assert_with(bpf_cmp_unlikely(cookie, >=, 1), cookie + 100); return 0; } diff --git a/tools/testing/selftests/bpf/progs/iters_task_vma.c b/tools/testing/selftests/bpf/progs/iters_task_vma.c index e085a51d153ee..dc0c3691dcc2b 100644 --- a/tools/testing/selftests/bpf/progs/iters_task_vma.c +++ b/tools/testing/selftests/bpf/progs/iters_task_vma.c @@ -28,9 +28,8 @@ int iter_task_vma_for_each(const void *ctx) return 0; bpf_for_each(task_vma, vma, task, 0) { - if (seen >= 1000) + if (bpf_cmp_unlikely(seen, >=, 1000)) break; - barrier_var(seen); vm_ranges[seen].vm_start = vma->vm_start; vm_ranges[seen].vm_end = vma->vm_end; From 624cd2a17672f4596fee97a5558bc990778bbcf9 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 26 Dec 2023 11:11:45 -0800 Subject: [PATCH 3/6] selftests/bpf: Convert exceptions_assert.c to bpf_cmp Convert exceptions_assert.c to bpf_cmp_unlikely() macro. Since bpf_assert(bpf_cmp_unlikely(var, ==, 100)); other code; will generate assembly code: if r1 == 100 goto L2; r0 = 0 call bpf_throw L1: other code; ... L2: goto L1; LLVM generates redundant basic block with extra goto. LLVM will be fixed eventually. Right now it's less efficient than __bpf_assert(var, ==, 100) macro that produces: if r1 == 100 goto L1; r0 = 0 call bpf_throw L1: other code; But extra goto doesn't hurt the verification process. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Jiri Olsa Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/bpf/20231226191148.48536-4-alexei.starovoitov@gmail.com --- .../selftests/bpf/progs/exceptions_assert.c | 80 +++++++++---------- 1 file changed, 40 insertions(+), 40 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/exceptions_assert.c b/tools/testing/selftests/bpf/progs/exceptions_assert.c index 0ef81040da596..5e0a1ca96d4e2 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_assert.c +++ b/tools/testing/selftests/bpf/progs/exceptions_assert.c @@ -11,51 +11,51 @@ #define check_assert(type, op, name, value) \ SEC("?tc") \ __log_level(2) __failure \ - int check_assert_##op##_##name(void *ctx) \ + int check_assert_##name(void *ctx) \ { \ type num = bpf_ktime_get_ns(); \ - bpf_assert_##op(num, value); \ + bpf_assert(bpf_cmp_unlikely(num, op, value)); \ return *(u64 *)num; \ } -__msg(": R0_w=0xffffffff80000000 R10=fp0") -check_assert(s64, eq, int_min, INT_MIN); -__msg(": R0_w=0x7fffffff R10=fp0") -check_assert(s64, eq, int_max, INT_MAX); -__msg(": R0_w=0 R10=fp0") -check_assert(s64, eq, zero, 0); -__msg(": R0_w=0x8000000000000000 R1_w=0x8000000000000000 R10=fp0") -check_assert(s64, eq, llong_min, LLONG_MIN); -__msg(": R0_w=0x7fffffffffffffff R1_w=0x7fffffffffffffff R10=fp0") -check_assert(s64, eq, llong_max, LLONG_MAX); - -__msg(": R0_w=scalar(smax=0x7ffffffe) R10=fp0") -check_assert(s64, lt, pos, INT_MAX); -__msg(": R0_w=scalar(smax=-1,umin=0x8000000000000000,var_off=(0x8000000000000000; 0x7fffffffffffffff))") -check_assert(s64, lt, zero, 0); -__msg(": R0_w=scalar(smax=0xffffffff7fffffff,umin=0x8000000000000000,umax=0xffffffff7fffffff,var_off=(0x8000000000000000; 0x7fffffffffffffff))") -check_assert(s64, lt, neg, INT_MIN); - -__msg(": R0_w=scalar(smax=0x7fffffff) R10=fp0") -check_assert(s64, le, pos, INT_MAX); -__msg(": R0_w=scalar(smax=0) R10=fp0") -check_assert(s64, le, zero, 0); -__msg(": R0_w=scalar(smax=0xffffffff80000000,umin=0x8000000000000000,umax=0xffffffff80000000,var_off=(0x8000000000000000; 0x7fffffffffffffff))") -check_assert(s64, le, neg, INT_MIN); - -__msg(": R0_w=scalar(smin=umin=0x80000000,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") -check_assert(s64, gt, pos, INT_MAX); -__msg(": R0_w=scalar(smin=umin=1,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") -check_assert(s64, gt, zero, 0); -__msg(": R0_w=scalar(smin=0xffffffff80000001) R10=fp0") -check_assert(s64, gt, neg, INT_MIN); - -__msg(": R0_w=scalar(smin=umin=0x7fffffff,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") -check_assert(s64, ge, pos, INT_MAX); -__msg(": R0_w=scalar(smin=0,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff)) R10=fp0") -check_assert(s64, ge, zero, 0); -__msg(": R0_w=scalar(smin=0xffffffff80000000) R10=fp0") -check_assert(s64, ge, neg, INT_MIN); +__msg(": R0_w=0xffffffff80000000") +check_assert(s64, ==, eq_int_min, INT_MIN); +__msg(": R0_w=0x7fffffff") +check_assert(s64, ==, eq_int_max, INT_MAX); +__msg(": R0_w=0") +check_assert(s64, ==, eq_zero, 0); +__msg(": R0_w=0x8000000000000000 R1_w=0x8000000000000000") +check_assert(s64, ==, eq_llong_min, LLONG_MIN); +__msg(": R0_w=0x7fffffffffffffff R1_w=0x7fffffffffffffff") +check_assert(s64, ==, eq_llong_max, LLONG_MAX); + +__msg(": R0_w=scalar(id=1,smax=0x7ffffffe)") +check_assert(s64, <, lt_pos, INT_MAX); +__msg(": R0_w=scalar(id=1,smax=-1,umin=0x8000000000000000,var_off=(0x8000000000000000; 0x7fffffffffffffff))") +check_assert(s64, <, lt_zero, 0); +__msg(": R0_w=scalar(id=1,smax=0xffffffff7fffffff") +check_assert(s64, <, lt_neg, INT_MIN); + +__msg(": R0_w=scalar(id=1,smax=0x7fffffff)") +check_assert(s64, <=, le_pos, INT_MAX); +__msg(": R0_w=scalar(id=1,smax=0)") +check_assert(s64, <=, le_zero, 0); +__msg(": R0_w=scalar(id=1,smax=0xffffffff80000000") +check_assert(s64, <=, le_neg, INT_MIN); + +__msg(": R0_w=scalar(id=1,smin=umin=0x80000000,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") +check_assert(s64, >, gt_pos, INT_MAX); +__msg(": R0_w=scalar(id=1,smin=umin=1,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") +check_assert(s64, >, gt_zero, 0); +__msg(": R0_w=scalar(id=1,smin=0xffffffff80000001") +check_assert(s64, >, gt_neg, INT_MIN); + +__msg(": R0_w=scalar(id=1,smin=umin=0x7fffffff,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") +check_assert(s64, >=, ge_pos, INT_MAX); +__msg(": R0_w=scalar(id=1,smin=0,umax=0x7fffffffffffffff,var_off=(0x0; 0x7fffffffffffffff))") +check_assert(s64, >=, ge_zero, 0); +__msg(": R0_w=scalar(id=1,smin=0xffffffff80000000") +check_assert(s64, >=, ge_neg, INT_MIN); SEC("?tc") __log_level(2) __failure From 907dbd3ede5ffd4f9519dd1fae2a8a983603bf3b Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 26 Dec 2023 11:11:46 -0800 Subject: [PATCH 4/6] selftests/bpf: Remove bpf_assert_eq-like macros. Since the last user was converted to bpf_cmp, remove bpf_assert_eq/ne/... macros. __bpf_assert_op() macro is kept for experiments, since it's slightly more efficient than bpf_assert(bpf_cmp_unlikely()) until LLVM is fixed. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Jiri Olsa Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/bpf/20231226191148.48536-5-alexei.starovoitov@gmail.com --- .../testing/selftests/bpf/bpf_experimental.h | 150 ------------------ 1 file changed, 150 deletions(-) diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 19ed6c941c1c4..2ef9949fbd637 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -341,156 +341,6 @@ l_true: \ */ #define bpf_assert_with(cond, value) if (!(cond)) bpf_throw(value); -/* Description - * Assert that LHS is equal to RHS. This statement updates the known value - * of LHS during verification. Note that RHS must be a constant value, and - * must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the value zero when the assertion fails. - */ -#define bpf_assert_eq(LHS, RHS) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, ==, RHS, 0, true); \ - }) - -/* Description - * Assert that LHS is equal to RHS. This statement updates the known value - * of LHS during verification. Note that RHS must be a constant value, and - * must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the specified value when the assertion fails. - */ -#define bpf_assert_eq_with(LHS, RHS, value) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, ==, RHS, value, true); \ - }) - -/* Description - * Assert that LHS is less than RHS. This statement updates the known - * bounds of LHS during verification. Note that RHS must be a constant - * value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the value zero when the assertion fails. - */ -#define bpf_assert_lt(LHS, RHS) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, <, RHS, 0, false); \ - }) - -/* Description - * Assert that LHS is less than RHS. This statement updates the known - * bounds of LHS during verification. Note that RHS must be a constant - * value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the specified value when the assertion fails. - */ -#define bpf_assert_lt_with(LHS, RHS, value) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, <, RHS, value, false); \ - }) - -/* Description - * Assert that LHS is greater than RHS. This statement updates the known - * bounds of LHS during verification. Note that RHS must be a constant - * value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the value zero when the assertion fails. - */ -#define bpf_assert_gt(LHS, RHS) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, >, RHS, 0, false); \ - }) - -/* Description - * Assert that LHS is greater than RHS. This statement updates the known - * bounds of LHS during verification. Note that RHS must be a constant - * value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the specified value when the assertion fails. - */ -#define bpf_assert_gt_with(LHS, RHS, value) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, >, RHS, value, false); \ - }) - -/* Description - * Assert that LHS is less than or equal to RHS. This statement updates the - * known bounds of LHS during verification. Note that RHS must be a - * constant value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the value zero when the assertion fails. - */ -#define bpf_assert_le(LHS, RHS) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, <=, RHS, 0, false); \ - }) - -/* Description - * Assert that LHS is less than or equal to RHS. This statement updates the - * known bounds of LHS during verification. Note that RHS must be a - * constant value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the specified value when the assertion fails. - */ -#define bpf_assert_le_with(LHS, RHS, value) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, <=, RHS, value, false); \ - }) - -/* Description - * Assert that LHS is greater than or equal to RHS. This statement updates - * the known bounds of LHS during verification. Note that RHS must be a - * constant value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the value zero when the assertion fails. - */ -#define bpf_assert_ge(LHS, RHS) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, >=, RHS, 0, false); \ - }) - -/* Description - * Assert that LHS is greater than or equal to RHS. This statement updates - * the known bounds of LHS during verification. Note that RHS must be a - * constant value, and must fit within the data type of LHS. - * Returns - * Void. - * Throws - * An exception with the specified value when the assertion fails. - */ -#define bpf_assert_ge_with(LHS, RHS, value) \ - ({ \ - barrier_var(LHS); \ - __bpf_assert_op(LHS, >=, RHS, value, false); \ - }) - /* Description * Assert that LHS is in the range [BEG, END] (inclusive of both). This * statement updates the known bounds of LHS during verification. Note From 0bcc62aa9813f519db58df14ddf1d523fa971e62 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 26 Dec 2023 11:11:47 -0800 Subject: [PATCH 5/6] bpf: Add bpf_nop_mov() asm macro. bpf_nop_mov(var) asm macro emits nop register move: rX = rX. If 'var' is a scalar and not a fixed constant the verifier will assign ID to it. If it's later spilled the stack slot will carry that ID as well. Hence the range refining comparison "if rX < const" will update all copies including spilled slot. This macro is a temporary workaround until the verifier gets smarter. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231226191148.48536-6-alexei.starovoitov@gmail.com --- tools/testing/selftests/bpf/bpf_experimental.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 2ef9949fbd637..f44875f8b3678 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -323,6 +323,11 @@ l_true: \ }) #endif +#ifndef bpf_nop_mov +#define bpf_nop_mov(var) \ + asm volatile("%[reg]=%[reg]"::[reg]"r"((short)var)) +#endif + /* Description * Assert that a conditional expression is true. * Returns From 7e3811cb998f0e2493677c7daf6cefb4ece27111 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 26 Dec 2023 11:11:48 -0800 Subject: [PATCH 6/6] selftests/bpf: Convert profiler.c to bpf_cmp. Convert profiler[123].c to "volatile compare" to compare barrier_var() approach vs bpf_cmp_likely() vs bpf_cmp_unlikely(). bpf_cmp_unlikely() produces correct code, but takes much longer to verify: ./veristat -C -e prog,insns,states before after_with_unlikely Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) ------------------------------------ --------- --------- ------------------ ---------- ---------- ----------------- kprobe__proc_sys_write 1603 19606 +18003 (+1123.08%) 123 1678 +1555 (+1264.23%) kprobe__vfs_link 11815 70305 +58490 (+495.05%) 971 4967 +3996 (+411.53%) kprobe__vfs_symlink 5464 42896 +37432 (+685.07%) 434 3126 +2692 (+620.28%) kprobe_ret__do_filp_open 5641 44578 +38937 (+690.25%) 446 3162 +2716 (+608.97%) raw_tracepoint__sched_process_exec 2770 35962 +33192 (+1198.27%) 226 3121 +2895 (+1280.97%) raw_tracepoint__sched_process_exit 1526 2135 +609 (+39.91%) 133 208 +75 (+56.39%) raw_tracepoint__sched_process_fork 265 337 +72 (+27.17%) 19 24 +5 (+26.32%) tracepoint__syscalls__sys_enter_kill 18782 140407 +121625 (+647.56%) 1286 12176 +10890 (+846.81%) bpf_cmp_likely() is equivalent to barrier_var(): ./veristat -C -e prog,insns,states before after_with_likely Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) ------------------------------------ --------- --------- -------------- ---------- ---------- ------------- kprobe__proc_sys_write 1603 1663 +60 (+3.74%) 123 127 +4 (+3.25%) kprobe__vfs_link 11815 12090 +275 (+2.33%) 971 971 +0 (+0.00%) kprobe__vfs_symlink 5464 5448 -16 (-0.29%) 434 426 -8 (-1.84%) kprobe_ret__do_filp_open 5641 5739 +98 (+1.74%) 446 446 +0 (+0.00%) raw_tracepoint__sched_process_exec 2770 2608 -162 (-5.85%) 226 216 -10 (-4.42%) raw_tracepoint__sched_process_exit 1526 1526 +0 (+0.00%) 133 133 +0 (+0.00%) raw_tracepoint__sched_process_fork 265 265 +0 (+0.00%) 19 19 +0 (+0.00%) tracepoint__syscalls__sys_enter_kill 18782 18970 +188 (+1.00%) 1286 1286 +0 (+0.00%) kprobe__proc_sys_write 2700 2809 +109 (+4.04%) 107 109 +2 (+1.87%) kprobe__vfs_link 12238 12366 +128 (+1.05%) 267 269 +2 (+0.75%) kprobe__vfs_symlink 7139 7365 +226 (+3.17%) 167 175 +8 (+4.79%) kprobe_ret__do_filp_open 7264 7070 -194 (-2.67%) 180 182 +2 (+1.11%) raw_tracepoint__sched_process_exec 3768 3453 -315 (-8.36%) 211 199 -12 (-5.69%) raw_tracepoint__sched_process_exit 3138 3138 +0 (+0.00%) 83 83 +0 (+0.00%) raw_tracepoint__sched_process_fork 265 265 +0 (+0.00%) 19 19 +0 (+0.00%) tracepoint__syscalls__sys_enter_kill 26679 24327 -2352 (-8.82%) 1067 1037 -30 (-2.81%) kprobe__proc_sys_write 1833 1833 +0 (+0.00%) 157 157 +0 (+0.00%) kprobe__vfs_link 9995 10127 +132 (+1.32%) 803 803 +0 (+0.00%) kprobe__vfs_symlink 5606 5672 +66 (+1.18%) 451 451 +0 (+0.00%) kprobe_ret__do_filp_open 5716 5782 +66 (+1.15%) 462 462 +0 (+0.00%) raw_tracepoint__sched_process_exec 3042 3042 +0 (+0.00%) 278 278 +0 (+0.00%) raw_tracepoint__sched_process_exit 1680 1680 +0 (+0.00%) 146 146 +0 (+0.00%) raw_tracepoint__sched_process_fork 299 299 +0 (+0.00%) 25 25 +0 (+0.00%) tracepoint__syscalls__sys_enter_kill 18372 18372 +0 (+0.00%) 1558 1558 +0 (+0.00%) default (mcpu=v3), no_alu32, cpuv4 have similar differences. Note one place where bpf_nop_mov() is used to workaround the verifier lack of link between the scalar register and its spill to stack. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20231226191148.48536-7-alexei.starovoitov@gmail.com --- .../selftests/bpf/progs/profiler.inc.h | 64 ++++++------------- 1 file changed, 18 insertions(+), 46 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/profiler.inc.h b/tools/testing/selftests/bpf/progs/profiler.inc.h index ba99d17dac544..de3b6e4e4d0a7 100644 --- a/tools/testing/selftests/bpf/progs/profiler.inc.h +++ b/tools/testing/selftests/bpf/progs/profiler.inc.h @@ -7,6 +7,7 @@ #include "profiler.h" #include "err.h" +#include "bpf_experimental.h" #ifndef NULL #define NULL 0 @@ -221,8 +222,7 @@ static INLINE void* read_full_cgroup_path(struct kernfs_node* cgroup_node, return payload; if (cgroup_node == cgroup_root_node) *root_pos = payload - payload_start; - if (filepart_length <= MAX_PATH) { - barrier_var(filepart_length); + if (bpf_cmp_likely(filepart_length, <=, MAX_PATH)) { payload += filepart_length; } cgroup_node = BPF_CORE_READ(cgroup_node, parent); @@ -305,9 +305,7 @@ static INLINE void* populate_cgroup_info(struct cgroup_data_t* cgroup_data, size_t cgroup_root_length = bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(root_kernfs, name)); - barrier_var(cgroup_root_length); - if (cgroup_root_length <= MAX_PATH) { - barrier_var(cgroup_root_length); + if (bpf_cmp_likely(cgroup_root_length, <=, MAX_PATH)) { cgroup_data->cgroup_root_length = cgroup_root_length; payload += cgroup_root_length; } @@ -315,9 +313,7 @@ static INLINE void* populate_cgroup_info(struct cgroup_data_t* cgroup_data, size_t cgroup_proc_length = bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(proc_kernfs, name)); - barrier_var(cgroup_proc_length); - if (cgroup_proc_length <= MAX_PATH) { - barrier_var(cgroup_proc_length); + if (bpf_cmp_likely(cgroup_proc_length, <=, MAX_PATH)) { cgroup_data->cgroup_proc_length = cgroup_proc_length; payload += cgroup_proc_length; } @@ -347,9 +343,7 @@ static INLINE void* populate_var_metadata(struct var_metadata_t* metadata, metadata->comm_length = 0; size_t comm_length = bpf_core_read_str(payload, TASK_COMM_LEN, &task->comm); - barrier_var(comm_length); - if (comm_length <= TASK_COMM_LEN) { - barrier_var(comm_length); + if (bpf_cmp_likely(comm_length, <=, TASK_COMM_LEN)) { metadata->comm_length = comm_length; payload += comm_length; } @@ -494,10 +488,9 @@ read_absolute_file_path_from_dentry(struct dentry* filp_dentry, void* payload) filepart_length = bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(filp_dentry, d_name.name)); - barrier_var(filepart_length); - if (filepart_length > MAX_PATH) + bpf_nop_mov(filepart_length); + if (bpf_cmp_unlikely(filepart_length, >, MAX_PATH)) break; - barrier_var(filepart_length); payload += filepart_length; length += filepart_length; @@ -579,9 +572,7 @@ ssize_t BPF_KPROBE(kprobe__proc_sys_write, size_t sysctl_val_length = bpf_probe_read_kernel_str(payload, CTL_MAXNAME, buf); - barrier_var(sysctl_val_length); - if (sysctl_val_length <= CTL_MAXNAME) { - barrier_var(sysctl_val_length); + if (bpf_cmp_likely(sysctl_val_length, <=, CTL_MAXNAME)) { sysctl_data->sysctl_val_length = sysctl_val_length; payload += sysctl_val_length; } @@ -590,9 +581,7 @@ ssize_t BPF_KPROBE(kprobe__proc_sys_write, bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(filp, f_path.dentry, d_name.name)); - barrier_var(sysctl_path_length); - if (sysctl_path_length <= MAX_PATH) { - barrier_var(sysctl_path_length); + if (bpf_cmp_likely(sysctl_path_length, <=, MAX_PATH)) { sysctl_data->sysctl_path_length = sysctl_path_length; payload += sysctl_path_length; } @@ -658,9 +647,7 @@ int raw_tracepoint__sched_process_exit(void* ctx) kill_data->kill_target_cgroup_proc_length = 0; size_t comm_length = bpf_core_read_str(payload, TASK_COMM_LEN, &task->comm); - barrier_var(comm_length); - if (comm_length <= TASK_COMM_LEN) { - barrier_var(comm_length); + if (bpf_cmp_likely(comm_length, <=, TASK_COMM_LEN)) { kill_data->kill_target_name_length = comm_length; payload += comm_length; } @@ -669,9 +656,7 @@ int raw_tracepoint__sched_process_exit(void* ctx) bpf_probe_read_kernel_str(payload, KILL_TARGET_LEN, BPF_CORE_READ(proc_kernfs, name)); - barrier_var(cgroup_proc_length); - if (cgroup_proc_length <= KILL_TARGET_LEN) { - barrier_var(cgroup_proc_length); + if (bpf_cmp_likely(cgroup_proc_length, <=, KILL_TARGET_LEN)) { kill_data->kill_target_cgroup_proc_length = cgroup_proc_length; payload += cgroup_proc_length; } @@ -731,9 +716,7 @@ int raw_tracepoint__sched_process_exec(struct bpf_raw_tracepoint_args* ctx) const char* filename = BPF_CORE_READ(bprm, filename); size_t bin_path_length = bpf_probe_read_kernel_str(payload, MAX_FILENAME_LEN, filename); - barrier_var(bin_path_length); - if (bin_path_length <= MAX_FILENAME_LEN) { - barrier_var(bin_path_length); + if (bpf_cmp_likely(bin_path_length, <=, MAX_FILENAME_LEN)) { proc_exec_data->bin_path_length = bin_path_length; payload += bin_path_length; } @@ -743,8 +726,7 @@ int raw_tracepoint__sched_process_exec(struct bpf_raw_tracepoint_args* ctx) unsigned int cmdline_length = probe_read_lim(payload, arg_start, arg_end - arg_start, MAX_ARGS_LEN); - if (cmdline_length <= MAX_ARGS_LEN) { - barrier_var(cmdline_length); + if (bpf_cmp_likely(cmdline_length, <=, MAX_ARGS_LEN)) { proc_exec_data->cmdline_length = cmdline_length; payload += cmdline_length; } @@ -821,9 +803,7 @@ int kprobe_ret__do_filp_open(struct pt_regs* ctx) payload = populate_cgroup_info(&filemod_data->cgroup_data, task, payload); size_t len = read_absolute_file_path_from_dentry(filp_dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->dst_filepath_length = len; } @@ -876,17 +856,13 @@ int BPF_KPROBE(kprobe__vfs_link, payload = populate_cgroup_info(&filemod_data->cgroup_data, task, payload); size_t len = read_absolute_file_path_from_dentry(old_dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->src_filepath_length = len; } len = read_absolute_file_path_from_dentry(new_dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->dst_filepath_length = len; } @@ -936,16 +912,12 @@ int BPF_KPROBE(kprobe__vfs_symlink, struct inode* dir, struct dentry* dentry, size_t len = bpf_probe_read_kernel_str(payload, MAX_FILEPATH_LENGTH, oldname); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->src_filepath_length = len; } len = read_absolute_file_path_from_dentry(dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->dst_filepath_length = len; }