Messages in this thread | | | Date | Thu, 05 Mar 2020 16:32:30 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [PATCH v2] perf symbols: Consolidate symbol fixup issue |
| |
Leo Yan wrote: > After copying Arm64's perf archive with object files and perf.data file > to x86 laptop, the x86's perf kernel symbol resolution fails. It > outputs 'unknown' for all symbols parsing. > > This issue is root caused by the function elf__needs_adjust_symbols(), > x86 perf tool uses one weak version, Arm64 (and powerpc) has rewritten > their own version. elf__needs_adjust_symbols() decides if need to parse > symbols with the relative offset address; but x86 building uses the weak > function which misses to check for the elf type 'ET_DYN', so that it > cannot parse symbols in Arm DSOs due to the wrong result from > elf__needs_adjust_symbols(). > > The DSO parsing should not depend on any specific architecture perf > building; e.g. x86 perf tool can parse Arm and Arm64 DSOs, vice versa. > So this patch changes elf__needs_adjust_symbols() as a common function > and removes the arch specific functions for Arm64 and powerpc. > > In the common elf__needs_adjust_symbols(), it checks elf header and if > the machine type is one of Arm64/ppc/ppc64, it checks extra condition > for 'ET_DYN'. Finally, the Arm64 DSO can be parsed properly with x86's > perf tool. > > Before: > > # perf script > main 3258 1 branches: 0 [unknown] ([unknown]) => ffff800010c4665c [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c46670 [unknown] ([kernel.kallsyms]) => ffff800010c4eaec [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eaec [unknown] ([kernel.kallsyms]) => ffff800010c4eb00 [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eb08 [unknown] ([kernel.kallsyms]) => ffff800010c4e780 [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4e7a0 [unknown] ([kernel.kallsyms]) => ffff800010c4eeac [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eebc [unknown] ([kernel.kallsyms]) => ffff800010c4ed80 [unknown] ([kernel.kallsyms]) > > After: > > # perf script > main 3258 1 branches: 0 [unknown] ([unknown]) => ffff800010c4665c coresight_timeout+0x54 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c46670 coresight_timeout+0x68 ([kernel.kallsyms]) => ffff800010c4eaec etm4_enable_hw+0x3cc ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eaec etm4_enable_hw+0x3cc ([kernel.kallsyms]) => ffff800010c4eb00 etm4_enable_hw+0x3e0 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eb08 etm4_enable_hw+0x3e8 ([kernel.kallsyms]) => ffff800010c4e780 etm4_enable_hw+0x60 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4e7a0 etm4_enable_hw+0x80 ([kernel.kallsyms]) => ffff800010c4eeac etm4_enable+0x2d4 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eebc etm4_enable+0x2e4 ([kernel.kallsyms]) => ffff800010c4ed80 etm4_enable+0x1a8 ([kernel.kallsyms]) >
I am not able to reproduce this since powerpc64 kernels are not being built as ET_EXEC anymore.
> v2: Fixed Arm64 and powerpc native building. > > Reported-by: Mike Leach <mike.leach@linaro.org> > Signed-off-by: Leo Yan <leo.yan@linaro.org> > --- > tools/perf/arch/arm64/util/Build | 1 - > tools/perf/arch/arm64/util/sym-handling.c | 19 ------------------- > tools/perf/arch/powerpc/util/Build | 1 - > tools/perf/arch/powerpc/util/sym-handling.c | 10 ---------- > tools/perf/util/symbol-elf.c | 8 +++++++- > 5 files changed, 7 insertions(+), 32 deletions(-) > delete mode 100644 tools/perf/arch/arm64/util/sym-handling.c > > diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build > index 0a7782c61209..789956f76d85 100644 > --- a/tools/perf/arch/arm64/util/Build > +++ b/tools/perf/arch/arm64/util/Build > @@ -1,6 +1,5 @@ > perf-y += header.o > perf-y += perf_regs.o > -perf-y += sym-handling.o > perf-$(CONFIG_DWARF) += dwarf-regs.o > perf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.o > perf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o > diff --git a/tools/perf/arch/arm64/util/sym-handling.c b/tools/perf/arch/arm64/util/sym-handling.c > deleted file mode 100644 > index 8dfa3e5229f1..000000000000 > --- a/tools/perf/arch/arm64/util/sym-handling.c > +++ /dev/null > @@ -1,19 +0,0 @@ > -// SPDX-License-Identifier: GPL-2.0-only > -/* > - * > - * Copyright (C) 2015 Naveen N. Rao, IBM Corporation > - */ > - > -#include "symbol.h" // for the elf__needs_adjust_symbols() prototype > -#include <stdbool.h> > - > -#ifdef HAVE_LIBELF_SUPPORT > -#include <gelf.h> > - > -bool elf__needs_adjust_symbols(GElf_Ehdr ehdr) > -{ > - return ehdr.e_type == ET_EXEC || > - ehdr.e_type == ET_REL || > - ehdr.e_type == ET_DYN; > -} > -#endif > diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build > index 7cf0b8803097..e5c9504f8586 100644 > --- a/tools/perf/arch/powerpc/util/Build > +++ b/tools/perf/arch/powerpc/util/Build > @@ -1,5 +1,4 @@ > perf-y += header.o > -perf-y += sym-handling.o > perf-y += kvm-stat.o > perf-y += perf_regs.o > perf-y += mem-events.o > diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c > index abb7a12d8f93..0856b32f9e08 100644 > --- a/tools/perf/arch/powerpc/util/sym-handling.c > +++ b/tools/perf/arch/powerpc/util/sym-handling.c > @@ -10,16 +10,6 @@ > #include "probe-event.h" > #include "probe-file.h" > > -#ifdef HAVE_LIBELF_SUPPORT > -bool elf__needs_adjust_symbols(GElf_Ehdr ehdr) > -{ > - return ehdr.e_type == ET_EXEC || > - ehdr.e_type == ET_REL || > - ehdr.e_type == ET_DYN; > -} > - > -#endif > - > int arch__choose_best_symbol(struct symbol *syma, > struct symbol *symb __maybe_unused) > { > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c > index 1965aefccb02..ee788ac67415 100644 > --- a/tools/perf/util/symbol-elf.c > +++ b/tools/perf/util/symbol-elf.c > @@ -704,8 +704,14 @@ void symsrc__destroy(struct symsrc *ss) > close(ss->fd); > } > > -bool __weak elf__needs_adjust_symbols(GElf_Ehdr ehdr) > +bool elf__needs_adjust_symbols(GElf_Ehdr ehdr) > { > + if (ehdr.e_machine == EM_AARCH64 || > + ehdr.e_machine == EM_PPC || > + ehdr.e_machine == EM_PPC64) > + return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL || > + ehdr.e_type == ET_DYN; > + > return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL;
Patch looks good to me. However:
This is only used for checking kernel, so I wonder if we can simply include check for ET_DYN across all architectures? This would only matter if there are architectures building their kernel as ET_DYN that _don't_ want to adjust symbols.
- Naveen
| |