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Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux…
…/kernel/git/jolsa/perf into perf/core Pull perf/core improvements and fixes from Jiri Olsa: * Handle the num array type in python properly (Sebastian Andrzej Siewior) * Fix wrong condition for allocation failure (Jiri Olsa) * Adjust callchain based on DWARF debug info on powerpc (Sukadev Bhattiprolu) * Fix a risk for doing free on uninitialized pointer in traceevent lib (Rickard Strandqvist) Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,266 @@ | ||
| /* | ||
| * Use DWARF Debug information to skip unnecessary callchain entries. | ||
| * | ||
| * Copyright (C) 2014 Sukadev Bhattiprolu, IBM Corporation. | ||
| * Copyright (C) 2014 Ulrich Weigand, IBM Corporation. | ||
| * | ||
| * This program is free software; you can redistribute it and/or | ||
| * modify it under the terms of the GNU General Public License | ||
| * as published by the Free Software Foundation; either version | ||
| * 2 of the License, or (at your option) any later version. | ||
| */ | ||
| #include <inttypes.h> | ||
| #include <dwarf.h> | ||
| #include <elfutils/libdwfl.h> | ||
|
|
||
| #include "util/thread.h" | ||
| #include "util/callchain.h" | ||
|
|
||
| /* | ||
| * When saving the callchain on Power, the kernel conservatively saves | ||
| * excess entries in the callchain. A few of these entries are needed | ||
| * in some cases but not others. If the unnecessary entries are not | ||
| * ignored, we end up with duplicate arcs in the call-graphs. Use | ||
| * DWARF debug information to skip over any unnecessary callchain | ||
| * entries. | ||
| * | ||
| * See function header for arch_adjust_callchain() below for more details. | ||
| * | ||
| * The libdwfl code in this file is based on code from elfutils | ||
| * (libdwfl/argp-std.c, libdwfl/tests/addrcfi.c, etc). | ||
| */ | ||
| static char *debuginfo_path; | ||
|
|
||
| static const Dwfl_Callbacks offline_callbacks = { | ||
| .debuginfo_path = &debuginfo_path, | ||
| .find_debuginfo = dwfl_standard_find_debuginfo, | ||
| .section_address = dwfl_offline_section_address, | ||
| }; | ||
|
|
||
|
|
||
| /* | ||
| * Use the DWARF expression for the Call-frame-address and determine | ||
| * if return address is in LR and if a new frame was allocated. | ||
| */ | ||
| static int check_return_reg(int ra_regno, Dwarf_Frame *frame) | ||
| { | ||
| Dwarf_Op ops_mem[2]; | ||
| Dwarf_Op dummy; | ||
| Dwarf_Op *ops = &dummy; | ||
| size_t nops; | ||
| int result; | ||
|
|
||
| result = dwarf_frame_register(frame, ra_regno, ops_mem, &ops, &nops); | ||
| if (result < 0) { | ||
| pr_debug("dwarf_frame_register() %s\n", dwarf_errmsg(-1)); | ||
| return -1; | ||
| } | ||
|
|
||
| /* | ||
| * Check if return address is on the stack. | ||
| */ | ||
| if (nops != 0 || ops != NULL) | ||
| return 0; | ||
|
|
||
| /* | ||
| * Return address is in LR. Check if a frame was allocated | ||
| * but not-yet used. | ||
| */ | ||
| result = dwarf_frame_cfa(frame, &ops, &nops); | ||
| if (result < 0) { | ||
| pr_debug("dwarf_frame_cfa() returns %d, %s\n", result, | ||
| dwarf_errmsg(-1)); | ||
| return -1; | ||
| } | ||
|
|
||
| /* | ||
| * If call frame address is in r1, no new frame was allocated. | ||
| */ | ||
| if (nops == 1 && ops[0].atom == DW_OP_bregx && ops[0].number == 1 && | ||
| ops[0].number2 == 0) | ||
| return 1; | ||
|
|
||
| /* | ||
| * A new frame was allocated but has not yet been used. | ||
| */ | ||
| return 2; | ||
| } | ||
|
|
||
| /* | ||
| * Get the DWARF frame from the .eh_frame section. | ||
| */ | ||
| static Dwarf_Frame *get_eh_frame(Dwfl_Module *mod, Dwarf_Addr pc) | ||
| { | ||
| int result; | ||
| Dwarf_Addr bias; | ||
| Dwarf_CFI *cfi; | ||
| Dwarf_Frame *frame; | ||
|
|
||
| cfi = dwfl_module_eh_cfi(mod, &bias); | ||
| if (!cfi) { | ||
| pr_debug("%s(): no CFI - %s\n", __func__, dwfl_errmsg(-1)); | ||
| return NULL; | ||
| } | ||
|
|
||
| result = dwarf_cfi_addrframe(cfi, pc, &frame); | ||
| if (result) { | ||
| pr_debug("%s(): %s\n", __func__, dwfl_errmsg(-1)); | ||
| return NULL; | ||
| } | ||
|
|
||
| return frame; | ||
| } | ||
|
|
||
| /* | ||
| * Get the DWARF frame from the .debug_frame section. | ||
| */ | ||
| static Dwarf_Frame *get_dwarf_frame(Dwfl_Module *mod, Dwarf_Addr pc) | ||
| { | ||
| Dwarf_CFI *cfi; | ||
| Dwarf_Addr bias; | ||
| Dwarf_Frame *frame; | ||
| int result; | ||
|
|
||
| cfi = dwfl_module_dwarf_cfi(mod, &bias); | ||
| if (!cfi) { | ||
| pr_debug("%s(): no CFI - %s\n", __func__, dwfl_errmsg(-1)); | ||
| return NULL; | ||
| } | ||
|
|
||
| result = dwarf_cfi_addrframe(cfi, pc, &frame); | ||
| if (result) { | ||
| pr_debug("%s(): %s\n", __func__, dwfl_errmsg(-1)); | ||
| return NULL; | ||
| } | ||
|
|
||
| return frame; | ||
| } | ||
|
|
||
| /* | ||
| * Return: | ||
| * 0 if return address for the program counter @pc is on stack | ||
| * 1 if return address is in LR and no new stack frame was allocated | ||
| * 2 if return address is in LR and a new frame was allocated (but not | ||
| * yet used) | ||
| * -1 in case of errors | ||
| */ | ||
| static int check_return_addr(const char *exec_file, Dwarf_Addr pc) | ||
| { | ||
| int rc = -1; | ||
| Dwfl *dwfl; | ||
| Dwfl_Module *mod; | ||
| Dwarf_Frame *frame; | ||
| int ra_regno; | ||
| Dwarf_Addr start = pc; | ||
| Dwarf_Addr end = pc; | ||
| bool signalp; | ||
|
|
||
| dwfl = dwfl_begin(&offline_callbacks); | ||
| if (!dwfl) { | ||
| pr_debug("dwfl_begin() failed: %s\n", dwarf_errmsg(-1)); | ||
| return -1; | ||
| } | ||
|
|
||
| if (dwfl_report_offline(dwfl, "", exec_file, -1) == NULL) { | ||
| pr_debug("dwfl_report_offline() failed %s\n", dwarf_errmsg(-1)); | ||
| goto out; | ||
| } | ||
|
|
||
| mod = dwfl_addrmodule(dwfl, pc); | ||
| if (!mod) { | ||
| pr_debug("dwfl_addrmodule() failed, %s\n", dwarf_errmsg(-1)); | ||
| goto out; | ||
| } | ||
|
|
||
| /* | ||
| * To work with split debug info files (eg: glibc), check both | ||
| * .eh_frame and .debug_frame sections of the ELF header. | ||
| */ | ||
| frame = get_eh_frame(mod, pc); | ||
| if (!frame) { | ||
| frame = get_dwarf_frame(mod, pc); | ||
| if (!frame) | ||
| goto out; | ||
| } | ||
|
|
||
| ra_regno = dwarf_frame_info(frame, &start, &end, &signalp); | ||
| if (ra_regno < 0) { | ||
| pr_debug("Return address register unavailable: %s\n", | ||
| dwarf_errmsg(-1)); | ||
| goto out; | ||
| } | ||
|
|
||
| rc = check_return_reg(ra_regno, frame); | ||
|
|
||
| out: | ||
| dwfl_end(dwfl); | ||
| return rc; | ||
| } | ||
|
|
||
| /* | ||
| * The callchain saved by the kernel always includes the link register (LR). | ||
| * | ||
| * 0: PERF_CONTEXT_USER | ||
| * 1: Program counter (Next instruction pointer) | ||
| * 2: LR value | ||
| * 3: Caller's caller | ||
| * 4: ... | ||
| * | ||
| * The value in LR is only needed when it holds a return address. If the | ||
| * return address is on the stack, we should ignore the LR value. | ||
| * | ||
| * Further, when the return address is in the LR, if a new frame was just | ||
| * allocated but the LR was not saved into it, then the LR contains the | ||
| * caller, slot 4: contains the caller's caller and the contents of slot 3: | ||
| * (chain->ips[3]) is undefined and must be ignored. | ||
| * | ||
| * Use DWARF debug information to determine if any entries need to be skipped. | ||
| * | ||
| * Return: | ||
| * index: of callchain entry that needs to be ignored (if any) | ||
| * -1 if no entry needs to be ignored or in case of errors | ||
| */ | ||
| int arch_skip_callchain_idx(struct machine *machine, struct thread *thread, | ||
| struct ip_callchain *chain) | ||
| { | ||
| struct addr_location al; | ||
| struct dso *dso = NULL; | ||
| int rc; | ||
| u64 ip; | ||
| u64 skip_slot = -1; | ||
|
|
||
| if (chain->nr < 3) | ||
| return skip_slot; | ||
|
|
||
| ip = chain->ips[2]; | ||
|
|
||
| thread__find_addr_location(thread, machine, PERF_RECORD_MISC_USER, | ||
| MAP__FUNCTION, ip, &al); | ||
|
|
||
| if (al.map) | ||
| dso = al.map->dso; | ||
|
|
||
| if (!dso) { | ||
| pr_debug("%" PRIx64 " dso is NULL\n", ip); | ||
| return skip_slot; | ||
| } | ||
|
|
||
| rc = check_return_addr(dso->long_name, ip); | ||
|
|
||
| pr_debug("DSO %s, nr %" PRIx64 ", ip 0x%" PRIx64 "rc %d\n", | ||
| dso->long_name, chain->nr, ip, rc); | ||
|
|
||
| if (rc == 0) { | ||
| /* | ||
| * Return address on stack. Ignore LR value in callchain | ||
| */ | ||
| skip_slot = 2; | ||
| } else if (rc == 2) { | ||
| /* | ||
| * New frame allocated but return address still in LR. | ||
| * Ignore the caller's caller entry in callchain. | ||
| */ | ||
| skip_slot = 3; | ||
| } | ||
| return skip_slot; | ||
| } |
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