| Message ID | fc380ddad57d90d338ea79f319c5f5d1dd6639b9.1418146300.git.naveen.n.rao@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Michael Ellerman |
| Headers | show |
On Tue, 2014-12-09 at 23:04 +0530, Naveen N. Rao wrote: > PPC64 ELF ABIv2 has a Global Entry Point (GEP) and a Local Entry Point > (LEP). For purposes of probing, we need the LEP. Offset to the LEP is > encoded in st_other. > > diff --git a/tools/perf/arch/powerpc/util/elf-sym-decode.c b/tools/perf/arch/powerpc/util/elf-sym-decode.c > new file mode 100644 > index 0000000..7434656 > --- /dev/null > +++ b/tools/perf/arch/powerpc/util/elf-sym-decode.c > @@ -0,0 +1,27 @@ > +/* > + * Decode offset from Global Entry Point to Local Entry Point on PPC64 > + * ELF ABIv2. > + * > + * Derived from definitions in arch/powerpc/kernel/module_64.c > + * > + * Copyright (C) 2014 Ananth N Mavinakayanahalli, 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 <gelf.h> > +#include "elf_sym.h" > + > +/* PowerPC64 ABIv2 specific values for the ELF64_Sym st_other field. */ > +#define STO_PPC64_LOCAL_BIT 5 > +#define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT) > +#define PPC64_LOCAL_ENTRY_OFFSET(other) \ > + (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2) You're in userspace, you should be able to get these from elf.h > +unsigned int arch_elf_sym_decode_offset(GElf_Sym *sym) > +{ > + return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other); What happens on ABIv1 ? We hope st_other is zero? > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c > index 67e4392..92a424e 100644 > --- a/tools/perf/util/symbol-elf.c > +++ b/tools/perf/util/symbol-elf.c > @@ -10,6 +10,7 @@ > #include "vdso.h" > #include <symbol/kallsyms.h> > #include "debug.h" > +#include "elf_sym.h" > > #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT > static int elf_getphdrnum(Elf *elf, size_t *dst) > @@ -848,6 +849,13 @@ int dso__load_sym(struct dso *dso, struct map *map, > (sym.st_value & 1)) > --sym.st_value; > > + /* > + * PPC64 ELF ABIv2 encodes Local Entry Point offset in > + * the st_other field > + */ > + if ((map->type == MAP__FUNCTION) && sym.st_other) > + sym.st_value += arch_elf_sym_decode_offset(&sym); I guess no other arch has needed to do anything like this. But if they did it's unlikely they'll want to do the exact same logic, ie. check st_other and add some value to st_value. To make it more generically useful you could just make it: > + if (map->type == MAP__FUNCTION) > + arch_elf_sym_decode(&sym); And do any other checks in the arch routine. cheers
On 2014/12/10 09:13PM, Michael Ellerman wrote: > On Tue, 2014-12-09 at 23:04 +0530, Naveen N. Rao wrote: > > PPC64 ELF ABIv2 has a Global Entry Point (GEP) and a Local Entry Point > > (LEP). For purposes of probing, we need the LEP. Offset to the LEP is > > encoded in st_other. > > > > diff --git a/tools/perf/arch/powerpc/util/elf-sym-decode.c b/tools/perf/arch/powerpc/util/elf-sym-decode.c > > new file mode 100644 > > index 0000000..7434656 > > --- /dev/null > > +++ b/tools/perf/arch/powerpc/util/elf-sym-decode.c > > @@ -0,0 +1,27 @@ > > +/* > > + * Decode offset from Global Entry Point to Local Entry Point on PPC64 > > + * ELF ABIv2. > > + * > > + * Derived from definitions in arch/powerpc/kernel/module_64.c > > + * > > + * Copyright (C) 2014 Ananth N Mavinakayanahalli, 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 <gelf.h> > > +#include "elf_sym.h" > > + > > +/* PowerPC64 ABIv2 specific values for the ELF64_Sym st_other field. */ > > +#define STO_PPC64_LOCAL_BIT 5 > > +#define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT) > > +#define PPC64_LOCAL_ENTRY_OFFSET(other) \ > > + (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2) > > You're in userspace, you should be able to get these from elf.h Ah, ok. > > > +unsigned int arch_elf_sym_decode_offset(GElf_Sym *sym) > > +{ > > + return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other); > > What happens on ABIv1 ? We hope st_other is zero? Yes, st_other is zero in ABIv1. > > > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c > > index 67e4392..92a424e 100644 > > --- a/tools/perf/util/symbol-elf.c > > +++ b/tools/perf/util/symbol-elf.c > > @@ -10,6 +10,7 @@ > > #include "vdso.h" > > #include <symbol/kallsyms.h> > > #include "debug.h" > > +#include "elf_sym.h" > > > > #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT > > static int elf_getphdrnum(Elf *elf, size_t *dst) > > @@ -848,6 +849,13 @@ int dso__load_sym(struct dso *dso, struct map *map, > > (sym.st_value & 1)) > > --sym.st_value; > > > > + /* > > + * PPC64 ELF ABIv2 encodes Local Entry Point offset in > > + * the st_other field > > + */ > > + if ((map->type == MAP__FUNCTION) && sym.st_other) > > + sym.st_value += arch_elf_sym_decode_offset(&sym); > > I guess no other arch has needed to do anything like this. > > But if they did it's unlikely they'll want to do the exact same logic, ie. > check st_other and add some value to st_value. To make it more generically > useful you could just make it: > > > + if (map->type == MAP__FUNCTION) > > + arch_elf_sym_decode(&sym); > > And do any other checks in the arch routine. Sure. Makes sense. - Naveen
diff --git a/tools/perf/arch/powerpc/Makefile b/tools/perf/arch/powerpc/Makefile index 6f7782b..8621439 100644 --- a/tools/perf/arch/powerpc/Makefile +++ b/tools/perf/arch/powerpc/Makefile @@ -3,4 +3,5 @@ PERF_HAVE_DWARF_REGS := 1 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/skip-callchain-idx.o endif +LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/elf-sym-decode.o LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/header.o diff --git a/tools/perf/arch/powerpc/util/elf-sym-decode.c b/tools/perf/arch/powerpc/util/elf-sym-decode.c new file mode 100644 index 0000000..7434656 --- /dev/null +++ b/tools/perf/arch/powerpc/util/elf-sym-decode.c @@ -0,0 +1,27 @@ +/* + * Decode offset from Global Entry Point to Local Entry Point on PPC64 + * ELF ABIv2. + * + * Derived from definitions in arch/powerpc/kernel/module_64.c + * + * Copyright (C) 2014 Ananth N Mavinakayanahalli, 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 <gelf.h> +#include "elf_sym.h" + +/* PowerPC64 ABIv2 specific values for the ELF64_Sym st_other field. */ +#define STO_PPC64_LOCAL_BIT 5 +#define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT) +#define PPC64_LOCAL_ENTRY_OFFSET(other) \ + (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2) + +unsigned int arch_elf_sym_decode_offset(GElf_Sym *sym) +{ + return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other); +} diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile index 58f6091..8f64557 100644 --- a/tools/perf/config/Makefile +++ b/tools/perf/config/Makefile @@ -378,6 +378,7 @@ ifeq ($(ARCH),powerpc) ifndef NO_DWARF CFLAGS += -DHAVE_SKIP_CALLCHAIN_IDX endif + CFLAGS += -DHAVE_ELF_SYM_DECODE endif ifndef NO_LIBUNWIND diff --git a/tools/perf/util/elf_sym.h b/tools/perf/util/elf_sym.h new file mode 100644 index 0000000..0176f21 --- /dev/null +++ b/tools/perf/util/elf_sym.h @@ -0,0 +1,13 @@ +#ifndef __PERF_ELF_SYM_H +#define __PERF_ELF_SYM_H + +#ifdef HAVE_ELF_SYM_DECODE +extern unsigned int arch_elf_sym_decode_offset(GElf_Sym *sym); +#else +static inline unsigned int arch_elf_sym_decode_offset(GElf_Sym *sym __maybe_unused) +{ + return 0; +} +#endif + +#endif /* __PERF_ELF_SYM_H */ diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 67e4392..92a424e 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -10,6 +10,7 @@ #include "vdso.h" #include <symbol/kallsyms.h> #include "debug.h" +#include "elf_sym.h" #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT static int elf_getphdrnum(Elf *elf, size_t *dst) @@ -848,6 +849,13 @@ int dso__load_sym(struct dso *dso, struct map *map, (sym.st_value & 1)) --sym.st_value; + /* + * PPC64 ELF ABIv2 encodes Local Entry Point offset in + * the st_other field + */ + if ((map->type == MAP__FUNCTION) && sym.st_other) + sym.st_value += arch_elf_sym_decode_offset(&sym); + if (dso->kernel || kmodule) { char dso_name[PATH_MAX];