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perf tools: Introduce regs_query_register_offset() for x86

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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 <hekuang@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.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: 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
Link: http://lkml.kernel.org/r/1441523623-152703-20-git-send-email-wangnan0@huawei.com
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan 2015-09-06 07:13:35 +00:00 committed by Arnaldo Carvalho de Melo
parent 63ab024a5b
commit bbbe6bf603
2 changed files with 89 additions and 34 deletions
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1
tools/perf/arch/x86/Makefile
View file

@ -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

122
tools/perf/arch/x86/util/dwarf-regs.c
View file

@ -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(). 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",
"$stack", /* Stack address instead of %sp */
"%bp",
"%si",
"%di",
struct pt_regs_offset {
const char *name;
int offset;
};
#define X86_64_MAX_REGS 16
const char *x86_64_regs_table[X86_64_MAX_REGS] = {
"%ax",
"%dx",
"%cx",
"%bx",
"%si",
"%di",
"%bp",
"%sp",
"%r8",
"%r9",
"%r10",
"%r11",
"%r12",
"%r13",
"%r14",
"%r15",
#define REG_OFFSET_END {.name = NULL, .offset = 0}
#ifdef __x86_64__
# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)}
# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = -1}
#else
# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = -1}
# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)}
#endif
static const struct pt_regs_offset x86_32_regoffset_table[] = {
REG_OFFSET_NAME_32("%ax", eax),
REG_OFFSET_NAME_32("%cx", ecx),
REG_OFFSET_NAME_32("%dx", edx),
REG_OFFSET_NAME_32("%bx", ebx),
REG_OFFSET_NAME_32("$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,
};
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;
}