From bbbe6bf6037d77816c4a19aaf35f4cecf662b49a Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Sun, 6 Sep 2015 07:13:35 +0000 Subject: [PATCH] perf tools: Introduce regs_query_register_offset() for x86 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. get_arch_regstr() switches to regoffset_table and the old string table is dropped. Signed-off-by: He Kuang Acked-by: Masami Hiramatsu Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: Daniel Borkmann Cc: David Ahern Cc: He Kuang Cc: Jiri Olsa Cc: Kaixu Xia Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1441523623-152703-20-git-send-email-wangnan0@huawei.com Signed-off-by: Wang Nan Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/arch/x86/Makefile | 1 + tools/perf/arch/x86/util/dwarf-regs.c | 122 +++++++++++++++++++------- 2 files changed, 89 insertions(+), 34 deletions(-) diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile index 21322e0385b8..09ba923debe8 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/dwarf-regs.c b/tools/perf/arch/x86/util/dwarf-regs.c index a08de0a35b83..9223c164e545 100644 --- a/tools/perf/arch/x86/util/dwarf-regs.c +++ b/tools/perf/arch/x86/util/dwarf-regs.c @@ -21,55 +21,109 @@ */ #include +#include /* for EINVAL */ +#include /* for strcmp */ +#include /* for struct pt_regs */ +#include /* for offsetof */ #include /* - * 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(). Use + * the order 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; } -- 2.20.1