Messages in this thread | | | From | 平松雅巳 / HIRAMATU,MASAMI <> | Subject | RE: [PATCH 23/31] perf tools: Introduce regs_query_register_offset() for x86 | Date | Tue, 1 Sep 2015 11:47:41 +0000 |
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> From: Wang Nan [mailto:wangnan0@huawei.com] > > regs_query_register_offset() is a helper function which converts > register name like "%rax" to offset of a register in 'struct pt_regs', > which is required by BPF prologue generator. Since the function is > identical, try to reuse the code in arch/x86/kernel/ptrace.c. > > Comment inside dwarf-regs.c list the differences between this > implementation and kernel code.
Hmm, this also introduce a duplication of the code... It might be a good time to move them into arch/x86/lib/ and reuse it directly from perf code.
Thank you,
> > get_arch_regstr() switches to regoffset_table and the old string table > is dropped. > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > Signed-off-by: He Kuang <hekuang@huawei.com> > Cc: Alexei Starovoitov <ast@plumgrid.com> > Cc: Brendan Gregg <brendan.d.gregg@gmail.com> > Cc: Daniel Borkmann <daniel@iogearbox.net> > Cc: David Ahern <dsahern@gmail.com> > Cc: He Kuang <hekuang@huawei.com> > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Kaixu Xia <xiakaixu@huawei.com> > Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > Cc: Zefan Li <lizefan@huawei.com> > Cc: pi3orama@163.com > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > --- > tools/perf/arch/x86/Makefile | 1 + > tools/perf/arch/x86/util/Build | 1 + > tools/perf/arch/x86/util/dwarf-regs.c | 122 ++++++++++++++++++++++++---------- > 3 files changed, 90 insertions(+), 34 deletions(-) > > diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile > index 21322e0..09ba923 100644 > --- a/tools/perf/arch/x86/Makefile > +++ b/tools/perf/arch/x86/Makefile > @@ -2,3 +2,4 @@ ifndef NO_DWARF > PERF_HAVE_DWARF_REGS := 1 > endif > HAVE_KVM_STAT_SUPPORT := 1 > +PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET := 1 > diff --git a/tools/perf/arch/x86/util/Build b/tools/perf/arch/x86/util/Build > index 2c55e1b..d4d1f23 100644 > --- a/tools/perf/arch/x86/util/Build > +++ b/tools/perf/arch/x86/util/Build > @@ -4,6 +4,7 @@ libperf-y += pmu.o > libperf-y += kvm-stat.o > > libperf-$(CONFIG_DWARF) += dwarf-regs.o > +libperf-$(CONFIG_BPF_PROLOGUE) += dwarf-regs.o > > libperf-$(CONFIG_LIBUNWIND) += unwind-libunwind.o > libperf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o > diff --git a/tools/perf/arch/x86/util/dwarf-regs.c b/tools/perf/arch/x86/util/dwarf-regs.c > index a08de0a..de5b936 100644 > --- a/tools/perf/arch/x86/util/dwarf-regs.c > +++ b/tools/perf/arch/x86/util/dwarf-regs.c > @@ -21,55 +21,109 @@ > */ > > #include <stddef.h> > +#include <errno.h> /* for EINVAL */ > +#include <string.h> /* for strcmp */ > +#include <linux/ptrace.h> /* for struct pt_regs */ > +#include <linux/kernel.h> /* for offsetof */ > #include <dwarf-regs.h> > > /* > - * Generic dwarf analysis helpers > + * See arch/x86/kernel/ptrace.c. > + * Different from it: > + * > + * - Since struct pt_regs is defined differently for user and kernel, > + * but we want to use 'ax, bx' instead of 'rax, rbx' (which is struct > + * field name of user's pt_regs), we make REG_OFFSET_NAME to accept > + * both string name and reg field name. > + * > + * - Since accessing x86_32's pt_regs from x86_64 building is difficult > + * and vise versa, we simply fill offset with -1, so > + * get_arch_regstr() still works but regs_query_register_offset() > + * returns error. > + * The only inconvenience caused by it now is that we are not allowed > + * to generate BPF prologue for a x86_64 kernel if perf is built for > + * x86_32. This is really a rare usecase. > + * > + * - Order is different from kernel's ptrace.c for get_arch_regstr(), which > + * is defined by dwarf. > */ > > -#define X86_32_MAX_REGS 8 > -const char *x86_32_regs_table[X86_32_MAX_REGS] = { > - "%ax", > - "%cx", > - "%dx", > - "%bx", > - "$stack", /* Stack address instead of %sp */ > - "%bp", > - "%si", > - "%di", > +struct pt_regs_offset { > + const char *name; > + int offset; > +}; > + > +#define REG_OFFSET_END {.name = NULL, .offset = 0} > + > +#ifdef __x86_64__ > +# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} > +# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = -1} > +#else > +# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = -1} > +# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} > +#endif > + > +static const struct pt_regs_offset x86_32_regoffset_table[] = { > + REG_OFFSET_NAME_32("%ax", eax), > + REG_OFFSET_NAME_32("%cx", ecx), > + REG_OFFSET_NAME_32("%dx", edx), > + REG_OFFSET_NAME_32("%bx", ebx), > + REG_OFFSET_NAME_32("$stack", esp), /* Stack address instead of %sp */ > + REG_OFFSET_NAME_32("%bp", ebp), > + REG_OFFSET_NAME_32("%si", esi), > + REG_OFFSET_NAME_32("%di", edi), > + REG_OFFSET_END, > }; > > -#define X86_64_MAX_REGS 16 > -const char *x86_64_regs_table[X86_64_MAX_REGS] = { > - "%ax", > - "%dx", > - "%cx", > - "%bx", > - "%si", > - "%di", > - "%bp", > - "%sp", > - "%r8", > - "%r9", > - "%r10", > - "%r11", > - "%r12", > - "%r13", > - "%r14", > - "%r15", > +static const struct pt_regs_offset x86_64_regoffset_table[] = { > + REG_OFFSET_NAME_64("%ax", rax), > + REG_OFFSET_NAME_64("%dx", rdx), > + REG_OFFSET_NAME_64("%cx", rcx), > + REG_OFFSET_NAME_64("%bx", rbx), > + REG_OFFSET_NAME_64("%si", rsi), > + REG_OFFSET_NAME_64("%di", rdi), > + REG_OFFSET_NAME_64("%bp", rbp), > + REG_OFFSET_NAME_64("%sp", rsp), > + REG_OFFSET_NAME_64("%r8", r8), > + REG_OFFSET_NAME_64("%r9", r9), > + REG_OFFSET_NAME_64("%r10", r10), > + REG_OFFSET_NAME_64("%r11", r11), > + REG_OFFSET_NAME_64("%r12", r12), > + REG_OFFSET_NAME_64("%r13", r13), > + REG_OFFSET_NAME_64("%r14", r14), > + REG_OFFSET_NAME_64("%r15", r15), > + REG_OFFSET_END, > }; > > /* TODO: switching by dwarf address size */ > #ifdef __x86_64__ > -#define ARCH_MAX_REGS X86_64_MAX_REGS > -#define arch_regs_table x86_64_regs_table > +#define regoffset_table x86_64_regoffset_table > #else > -#define ARCH_MAX_REGS X86_32_MAX_REGS > -#define arch_regs_table x86_32_regs_table > +#define regoffset_table x86_32_regoffset_table > #endif > > +/* Minus 1 for the ending REG_OFFSET_END */ > +#define ARCH_MAX_REGS ((sizeof(regoffset_table) / sizeof(regoffset_table[0])) - 1) > + > /* Return architecture dependent register string (for kprobe-tracer) */ > const char *get_arch_regstr(unsigned int n) > { > - return (n < ARCH_MAX_REGS) ? arch_regs_table[n] : NULL; > + return (n < ARCH_MAX_REGS) ? regoffset_table[n].name : NULL; > +} > + > +/* Reuse code from arch/x86/kernel/ptrace.c */ > +/** > + * regs_query_register_offset() - query register offset from its name > + * @name: the name of a register > + * > + * regs_query_register_offset() returns the offset of a register in struct > + * pt_regs from its name. If the name is invalid, this returns -EINVAL; > + */ > +int regs_query_register_offset(const char *name) > +{ > + const struct pt_regs_offset *roff; > + for (roff = regoffset_table; roff->name != NULL; roff++) > + if (!strcmp(roff->name, name)) > + return roff->offset; > + return -EINVAL; > } > -- > 1.8.3.4
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