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Commit bbbe6bf6 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarHe Kuang <hekuang@huawei.com>
Acked-by: default avatarMasami 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: default avatarWang Nan <wangnan0@huawei.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 63ab024a

tools/perf/arch/x86/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -2,3 +2,4 @@ ifndef NO_DWARF 
PERF_HAVE_DWARF_REGS := 1

PERF_HAVE_DWARF_REGS := 1

endif

endif

HAVE_KVM_STAT_SUPPORT := 1

HAVE_KVM_STAT_SUPPORT := 1

PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET := 1

tools/perf/arch/x86/util/dwarf-regs.c

+88 −34
Original line number Original line Diff line number Diff line
@@ -21,55 +21,109 @@ 
 */

 */





#include <stddef.h>

#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>

#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

struct pt_regs_offset {

const char *x86_32_regs_table[X86_32_MAX_REGS] = {

	const char *name;

	"%ax",

	int offset;

	"%cx",

};

	"%dx",



	"%bx",

#define REG_OFFSET_END {.name = NULL, .offset = 0}

	"$stack",	/* Stack address instead of %sp */



	"%bp",

#ifdef __x86_64__

	"%si",

# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)}

	"%di",

# 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

static const struct pt_regs_offset x86_64_regoffset_table[] = {

const char *x86_64_regs_table[X86_64_MAX_REGS] = {

	REG_OFFSET_NAME_64("%ax",	rax),

	"%ax",

	REG_OFFSET_NAME_64("%dx",	rdx),

	"%dx",

	REG_OFFSET_NAME_64("%cx",	rcx),

	"%cx",

	REG_OFFSET_NAME_64("%bx",	rbx),

	"%bx",

	REG_OFFSET_NAME_64("%si",	rsi),

	"%si",

	REG_OFFSET_NAME_64("%di",	rdi),

	"%di",

	REG_OFFSET_NAME_64("%bp",	rbp),

	"%bp",

	REG_OFFSET_NAME_64("%sp",	rsp),

	"%sp",

	REG_OFFSET_NAME_64("%r8",	r8),

	"%r8",

	REG_OFFSET_NAME_64("%r9",	r9),

	"%r9",

	REG_OFFSET_NAME_64("%r10",	r10),

	"%r10",

	REG_OFFSET_NAME_64("%r11",	r11),

	"%r11",

	REG_OFFSET_NAME_64("%r12",	r12),

	"%r12",

	REG_OFFSET_NAME_64("%r13",	r13),

	"%r13",

	REG_OFFSET_NAME_64("%r14",	r14),

	"%r14",

	REG_OFFSET_NAME_64("%r15",	r15),

	"%r15",

	REG_OFFSET_END,

};

};





/* TODO: switching by dwarf address size */

/* TODO: switching by dwarf address size */

#ifdef __x86_64__

#ifdef __x86_64__

#define ARCH_MAX_REGS X86_64_MAX_REGS

#define regoffset_table x86_64_regoffset_table

#define arch_regs_table x86_64_regs_table

#else

#else

#define ARCH_MAX_REGS X86_32_MAX_REGS

#define regoffset_table x86_32_regoffset_table

#define arch_regs_table x86_32_regs_table

#endif

#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) */

/* Return architecture dependent register string (for kprobe-tracer) */

const char *get_arch_regstr(unsigned int n)

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;

}
 
}