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libbpf: Provide CO-RE variants of PT_REGS macros
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Syscall raw tracepoints have struct pt_regs pointer as tracepoint's first
argument. After that, reading any of pt_regs fields requires bpf_probe_read(),
even for tp_btf programs. Due to that, PT_REGS_PARMx macros are not usable as
is. This patch adds CO-RE variants of those macros that use BPF_CORE_READ() to
read necessary fields. This provides relocatable architecture-agnostic pt_regs
field accesses.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200313172336.1879637-4-andriin@fb.com
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Andrii Nakryiko authored and Daniel Borkmann committed Mar 13, 2020
1 parent d121e1d commit b8ebce8
Showing 1 changed file with 103 additions and 0 deletions.
103 changes: 103 additions & 0 deletions tools/lib/bpf/bpf_tracing.h
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,7 @@
#if defined(bpf_target_x86)

#if defined(__KERNEL__) || defined(__VMLINUX_H__)

#define PT_REGS_PARM1(x) ((x)->di)
#define PT_REGS_PARM2(x) ((x)->si)
#define PT_REGS_PARM3(x) ((x)->dx)
Expand All @@ -60,7 +61,20 @@
#define PT_REGS_RC(x) ((x)->ax)
#define PT_REGS_SP(x) ((x)->sp)
#define PT_REGS_IP(x) ((x)->ip)

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((x), di)
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((x), si)
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((x), dx)
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((x), cx)
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((x), r8)
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((x), sp)
#define PT_REGS_FP_CORE(x) BPF_CORE_READ((x), bp)
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((x), ax)
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((x), sp)
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), ip)

#else

#ifdef __i386__
/* i386 kernel is built with -mregparm=3 */
#define PT_REGS_PARM1(x) ((x)->eax)
Expand All @@ -73,7 +87,20 @@
#define PT_REGS_RC(x) ((x)->eax)
#define PT_REGS_SP(x) ((x)->esp)
#define PT_REGS_IP(x) ((x)->eip)

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((x), eax)
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((x), edx)
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((x), ecx)
#define PT_REGS_PARM4_CORE(x) 0
#define PT_REGS_PARM5_CORE(x) 0
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((x), esp)
#define PT_REGS_FP_CORE(x) BPF_CORE_READ((x), ebp)
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((x), eax)
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((x), esp)
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), eip)

#else

#define PT_REGS_PARM1(x) ((x)->rdi)
#define PT_REGS_PARM2(x) ((x)->rsi)
#define PT_REGS_PARM3(x) ((x)->rdx)
Expand All @@ -84,6 +111,18 @@
#define PT_REGS_RC(x) ((x)->rax)
#define PT_REGS_SP(x) ((x)->rsp)
#define PT_REGS_IP(x) ((x)->rip)

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((x), rdi)
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((x), rsi)
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((x), rdx)
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((x), rcx)
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((x), r8)
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((x), rsp)
#define PT_REGS_FP_CORE(x) BPF_CORE_READ((x), rbp)
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((x), rax)
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((x), rsp)
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), rip)

#endif
#endif

Expand All @@ -104,6 +143,17 @@ struct pt_regs;
#define PT_REGS_SP(x) (((PT_REGS_S390 *)(x))->gprs[15])
#define PT_REGS_IP(x) (((PT_REGS_S390 *)(x))->psw.addr)

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[2])
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[3])
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[4])
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[5])
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[6])
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), grps[14])
#define PT_REGS_FP_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[11])
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[2])
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), gprs[15])
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((PT_REGS_S390 *)(x), pdw.addr)

#elif defined(bpf_target_arm)

#define PT_REGS_PARM1(x) ((x)->uregs[0])
Expand All @@ -117,6 +167,17 @@ struct pt_regs;
#define PT_REGS_SP(x) ((x)->uregs[13])
#define PT_REGS_IP(x) ((x)->uregs[12])

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((x), uregs[0])
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((x), uregs[1])
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((x), uregs[2])
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((x), uregs[3])
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((x), uregs[4])
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((x), uregs[14])
#define PT_REGS_FP_CORE(x) BPF_CORE_READ((x), uregs[11])
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((x), uregs[0])
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((x), uregs[13])
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), uregs[12])

#elif defined(bpf_target_arm64)

/* arm64 provides struct user_pt_regs instead of struct pt_regs to userspace */
Expand All @@ -134,6 +195,17 @@ struct pt_regs;
#define PT_REGS_SP(x) (((PT_REGS_ARM64 *)(x))->sp)
#define PT_REGS_IP(x) (((PT_REGS_ARM64 *)(x))->pc)

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[0])
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[1])
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[2])
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[3])
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[4])
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[30])
#define PT_REGS_FP_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[29])
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), regs[0])
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), sp)
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((PT_REGS_ARM64 *)(x), pc)

#elif defined(bpf_target_mips)

#define PT_REGS_PARM1(x) ((x)->regs[4])
Expand All @@ -147,6 +219,17 @@ struct pt_regs;
#define PT_REGS_SP(x) ((x)->regs[29])
#define PT_REGS_IP(x) ((x)->cp0_epc)

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((x), regs[4])
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((x), regs[5])
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((x), regs[6])
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((x), regs[7])
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((x), regs[8])
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((x), regs[31])
#define PT_REGS_FP_CORE(x) BPF_CORE_READ((x), regs[30])
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((x), regs[1])
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((x), regs[29])
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), cp0_epc)

#elif defined(bpf_target_powerpc)

#define PT_REGS_PARM1(x) ((x)->gpr[3])
Expand All @@ -158,6 +241,15 @@ struct pt_regs;
#define PT_REGS_SP(x) ((x)->sp)
#define PT_REGS_IP(x) ((x)->nip)

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((x), gpr[3])
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((x), gpr[4])
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((x), gpr[5])
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((x), gpr[6])
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((x), gpr[7])
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((x), gpr[3])
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((x), sp)
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), nip)

#elif defined(bpf_target_sparc)

#define PT_REGS_PARM1(x) ((x)->u_regs[UREG_I0])
Expand All @@ -169,11 +261,22 @@ struct pt_regs;
#define PT_REGS_RC(x) ((x)->u_regs[UREG_I0])
#define PT_REGS_SP(x) ((x)->u_regs[UREG_FP])

#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ((x), u_regs[UREG_I0])
#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ((x), u_regs[UREG_I1])
#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ((x), u_regs[UREG_I2])
#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ((x), u_regs[UREG_I3])
#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ((x), u_regs[UREG_I4])
#define PT_REGS_RET_CORE(x) BPF_CORE_READ((x), u_regs[UREG_I7])
#define PT_REGS_RC_CORE(x) BPF_CORE_READ((x), u_regs[UREG_I0])
#define PT_REGS_SP_CORE(x) BPF_CORE_READ((x), u_regs[UREG_FP])

/* Should this also be a bpf_target check for the sparc case? */
#if defined(__arch64__)
#define PT_REGS_IP(x) ((x)->tpc)
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), tpc)
#else
#define PT_REGS_IP(x) ((x)->pc)
#define PT_REGS_IP_CORE(x) BPF_CORE_READ((x), pc)
#endif

#endif
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