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    Subject[RFC PATCH 4/4] perf-probe: Support probing on offline cross-arch binary
    Date
    Support probing on offline cross-architecture binary by
    adding getting the target machine arch from ELF and
    choose correct register string for the machine.

    Here is an example:
    -----
    $ mkdir tracing
    $ sudo perf probe --outdir=./tracing --vmlinux=./vmlinux-arm \
    do_sys_open '$vars'
    Added new event:
    probe:do_sys_open (on do_sys_open with $vars)

    You can now use it in all perf tools, such as:

    perf record -e probe:do_sys_open -aR sleep 1

    $ cat tracing/kprobe_events
    p:probe/do_sys_open _text+1282292 dfd=%r5:s32 filename=%r1:u32
    flags=%r6:s32 mode=%r3:u16 op=-60(%sp) fd=%r4:s32 tmp=%r7:u32
    -----
    Here, we can get probe/do_sys_open event by "copy & paste" from
    ./tracing/kprobe_events to target-machine's debugfs/tracing/kprobe_events

    To make sure it is correct:
    -----
    $ nm vmlinux-arm | grep "T _text"
    80008000 T _text
    $ nm vmlinux-arm | grep "T do_sys_open"
    801410f4 T do_sys_open
    $ expr `printf "%d + %d" 0x80008000 1282292`
    2148798708
    $ printf "%x\n" 2148798708
    801410f4
    -----
    So "_text+12882292" indicates do_sys_open on the target binary correctly.

    Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
    ---
    tools/perf/arch/arm/include/dwarf-regs-table.h | 9 +++
    tools/perf/arch/arm64/include/dwarf-regs-table.h | 13 +++++
    tools/perf/arch/powerpc/include/dwarf-regs-table.h | 27 ++++++++++
    tools/perf/arch/s390/include/dwarf-regs-table.h | 8 +++
    tools/perf/arch/sh/include/dwarf-regs-table.h | 25 +++++++++
    tools/perf/arch/sparc/include/dwarf-regs-table.h | 18 +++++++
    tools/perf/arch/x86/include/dwarf-regs-table.h | 14 +++++
    tools/perf/arch/xtensa/include/dwarf-regs-table.h | 8 +++
    tools/perf/util/Build | 1
    tools/perf/util/dwarf-regs.c | 55 ++++++++++++++++++++
    tools/perf/util/include/dwarf-regs.h | 6 ++
    tools/perf/util/probe-finder.c | 27 ++++++----
    tools/perf/util/probe-finder.h | 1
    13 files changed, 201 insertions(+), 11 deletions(-)
    create mode 100644 tools/perf/arch/arm/include/dwarf-regs-table.h
    create mode 100644 tools/perf/arch/arm64/include/dwarf-regs-table.h
    create mode 100644 tools/perf/arch/powerpc/include/dwarf-regs-table.h
    create mode 100644 tools/perf/arch/s390/include/dwarf-regs-table.h
    create mode 100644 tools/perf/arch/sh/include/dwarf-regs-table.h
    create mode 100644 tools/perf/arch/sparc/include/dwarf-regs-table.h
    create mode 100644 tools/perf/arch/x86/include/dwarf-regs-table.h
    create mode 100644 tools/perf/arch/xtensa/include/dwarf-regs-table.h
    create mode 100644 tools/perf/util/dwarf-regs.c

    diff --git a/tools/perf/arch/arm/include/dwarf-regs-table.h b/tools/perf/arch/arm/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..f298d03
    --- /dev/null
    +++ b/tools/perf/arch/arm/include/dwarf-regs-table.h
    @@ -0,0 +1,9 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +static const char * const arm_regstr_tbl[] = {
    + "%r0", "%r1", "%r2", "%r3", "%r4",
    + "%r5", "%r6", "%r7", "%r8", "%r9", "%r10",
    + "%fp", "%ip", "%sp", "%lr", "%pc",
    +};
    +#endif
    diff --git a/tools/perf/arch/arm64/include/dwarf-regs-table.h b/tools/perf/arch/arm64/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..2675936
    --- /dev/null
    +++ b/tools/perf/arch/arm64/include/dwarf-regs-table.h
    @@ -0,0 +1,13 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +static const char * const aarch64_regstr_tbl[] = {
    + "%r0", "%r1", "%r2", "%r3", "%r4",
    + "%r5", "%r6", "%r7", "%r8", "%r9",
    + "%r10", "%r11", "%r12", "%r13", "%r14",
    + "%r15", "%r16", "%r17", "%r18", "%r19",
    + "%r20", "%r21", "%r22", "%r23", "%r24",
    + "%r25", "%r26", "%r27", "%r28", "%r29",
    + "%lr", "%sp",
    +};
    +#endif
    diff --git a/tools/perf/arch/powerpc/include/dwarf-regs-table.h b/tools/perf/arch/powerpc/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..db4730f
    --- /dev/null
    +++ b/tools/perf/arch/powerpc/include/dwarf-regs-table.h
    @@ -0,0 +1,27 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +/*
    + * Reference:
    + * http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html
    + * http://refspecs.linux-foundation.org/elf/elfspec_ppc.pdf
    + */
    +#define REG_DWARFNUM_NAME(reg, idx) [idx] = "%" #reg
    +
    +static const char * const powerpc_regstr_tbl[] = {
    + "%gpr0", "%gpr1", "%gpr2", "%gpr3", "%gpr4",
    + "%gpr5", "%gpr6", "%gpr7", "%gpr8", "%gpr9",
    + "%gpr10", "%gpr11", "%gpr12", "%gpr13", "%gpr14",
    + "%gpr15", "%gpr16", "%gpr17", "%gpr18", "%gpr19",
    + "%gpr20", "%gpr21", "%gpr22", "%gpr23", "%gpr24",
    + "%gpr25", "%gpr26", "%gpr27", "%gpr28", "%gpr29",
    + "%gpr30", "%gpr31",
    + REG_DWARFNUM_NAME(msr, 66),
    + REG_DWARFNUM_NAME(ctr, 109),
    + REG_DWARFNUM_NAME(link, 108),
    + REG_DWARFNUM_NAME(xer, 101),
    + REG_DWARFNUM_NAME(dar, 119),
    + REG_DWARFNUM_NAME(dsisr, 118),
    +};
    +
    +#endif
    diff --git a/tools/perf/arch/s390/include/dwarf-regs-table.h b/tools/perf/arch/s390/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..9da74a9
    --- /dev/null
    +++ b/tools/perf/arch/s390/include/dwarf-regs-table.h
    @@ -0,0 +1,8 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +static const char * const s390_regstr_tbl[] = {
    + "%r0", "%r1", "%r2", "%r3", "%r4", "%r5", "%r6", "%r7",
    + "%r8", "%r9", "%r10", "%r11", "%r12", "%r13", "%r14", "%r15",
    +};
    +#endif
    diff --git a/tools/perf/arch/sh/include/dwarf-regs-table.h b/tools/perf/arch/sh/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..3a2deaf
    --- /dev/null
    +++ b/tools/perf/arch/sh/include/dwarf-regs-table.h
    @@ -0,0 +1,25 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +const char * const sh_regstr_tbl[] = {
    + "r0",
    + "r1",
    + "r2",
    + "r3",
    + "r4",
    + "r5",
    + "r6",
    + "r7",
    + "r8",
    + "r9",
    + "r10",
    + "r11",
    + "r12",
    + "r13",
    + "r14",
    + "r15",
    + "pc",
    + "pr",
    +};
    +
    +#endif
    diff --git a/tools/perf/arch/sparc/include/dwarf-regs-table.h b/tools/perf/arch/sparc/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..12c0761
    --- /dev/null
    +++ b/tools/perf/arch/sparc/include/dwarf-regs-table.h
    @@ -0,0 +1,18 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +static const char * const sparc_regstr_tbl[] = {
    + "%g0", "%g1", "%g2", "%g3", "%g4", "%g5", "%g6", "%g7",
    + "%o0", "%o1", "%o2", "%o3", "%o4", "%o5", "%sp", "%o7",
    + "%l0", "%l1", "%l2", "%l3", "%l4", "%l5", "%l6", "%l7",
    + "%i0", "%i1", "%i2", "%i3", "%i4", "%i5", "%fp", "%i7",
    + "%f0", "%f1", "%f2", "%f3", "%f4", "%f5", "%f6", "%f7",
    + "%f8", "%f9", "%f10", "%f11", "%f12", "%f13", "%f14", "%f15",
    + "%f16", "%f17", "%f18", "%f19", "%f20", "%f21", "%f22", "%f23",
    + "%f24", "%f25", "%f26", "%f27", "%f28", "%f29", "%f30", "%f31",
    + "%f32", "%f33", "%f34", "%f35", "%f36", "%f37", "%f38", "%f39",
    + "%f40", "%f41", "%f42", "%f43", "%f44", "%f45", "%f46", "%f47",
    + "%f48", "%f49", "%f50", "%f51", "%f52", "%f53", "%f54", "%f55",
    + "%f56", "%f57", "%f58", "%f59", "%f60", "%f61", "%f62", "%f63",
    +};
    +#endif
    diff --git a/tools/perf/arch/x86/include/dwarf-regs-table.h b/tools/perf/arch/x86/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..39ac7cb
    --- /dev/null
    +++ b/tools/perf/arch/x86/include/dwarf-regs-table.h
    @@ -0,0 +1,14 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +static const char * const x86_32_regstr_tbl[] = {
    + "%ax", "%cx", "%dx", "%bx", "$stack",/* Stack address instead of %sp */
    + "%bp", "%si", "%di",
    +};
    +
    +static const char * const x86_64_regstr_tbl[] = {
    + "%ax", "dx", "%cx", "%bx", "%si", "%di",
    + "%bp", "%sp", "%r8", "%r9", "%r10", "%r11",
    + "%r12", "%r13", "%r14", "%r15",
    +};
    +#endif
    diff --git a/tools/perf/arch/xtensa/include/dwarf-regs-table.h b/tools/perf/arch/xtensa/include/dwarf-regs-table.h
    new file mode 100644
    index 0000000..aa0444a
    --- /dev/null
    +++ b/tools/perf/arch/xtensa/include/dwarf-regs-table.h
    @@ -0,0 +1,8 @@
    +#ifdef DEFINE_DWARF_REGSTR_TABLE
    +/* This is included in perf/util/dwarf-regs.c */
    +
    +static const char * const xtensa_regstr_tbl[] = {
    + "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
    + "a8", "a9", "a10", "a11", "a12", "a13", "a14", "a15",
    +};
    +#endif
    diff --git a/tools/perf/util/Build b/tools/perf/util/Build
    index 91c5f6e..f1a6d17 100644
    --- a/tools/perf/util/Build
    +++ b/tools/perf/util/Build
    @@ -98,6 +98,7 @@ endif

    libperf-$(CONFIG_DWARF) += probe-finder.o
    libperf-$(CONFIG_DWARF) += dwarf-aux.o
    +libperf-$(CONFIG_DWARF) += dwarf-regs.o

    libperf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
    libperf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind-local.o
    diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
    new file mode 100644
    index 0000000..ce15816
    --- /dev/null
    +++ b/tools/perf/util/dwarf-regs.c
    @@ -0,0 +1,55 @@
    +/*
    + * dwarf-regs.c : Mapping of DWARF debug register numbers into register names.
    + *
    + * Written by: Masami Hiramatsu <mhiramat@kernel.org>
    + */
    +
    +#include <util.h>
    +#include <debug.h>
    +#include <dwarf-regs.h>
    +#include <elf.h>
    +
    +/* Define const char * {arch}_register_tbl[] */
    +#define DEFINE_DWARF_REGSTR_TABLE
    +#include "../arch/x86/include/dwarf-regs-table.h"
    +#include "../arch/arm/include/dwarf-regs-table.h"
    +#include "../arch/arm64/include/dwarf-regs-table.h"
    +#include "../arch/sh/include/dwarf-regs-table.h"
    +#include "../arch/powerpc/include/dwarf-regs-table.h"
    +#include "../arch/s390/include/dwarf-regs-table.h"
    +#include "../arch/sparc/include/dwarf-regs-table.h"
    +#include "../arch/xtensa/include/dwarf-regs-table.h"
    +
    +#define __get_dwarf_regstr(tbl, n) (((n) < ARRAY_SIZE(tbl)) ? (tbl)[(n)] : NULL)
    +
    +/* Return architecture dependent register string (for kprobe-tracer) */
    +const char *get_dwarf_regstr(unsigned int n, unsigned int machine)
    +{
    + switch (machine) {
    + case EM_NONE: /* Generic arch - use host arch */
    + return get_arch_regstr(n);
    + case EM_386:
    + return __get_dwarf_regstr(x86_32_regstr_tbl, n);
    + case EM_X86_64:
    + return __get_dwarf_regstr(x86_64_regstr_tbl, n);
    + case EM_ARM:
    + return __get_dwarf_regstr(arm_regstr_tbl, n);
    + case EM_AARCH64:
    + return __get_dwarf_regstr(aarch64_regstr_tbl, n);
    + case EM_SH:
    + return __get_dwarf_regstr(sh_regstr_tbl, n);
    + case EM_S390:
    + return __get_dwarf_regstr(s390_regstr_tbl, n);
    + case EM_PPC:
    + case EM_PPC64:
    + return __get_dwarf_regstr(powerpc_regstr_tbl, n);
    + case EM_SPARC:
    + case EM_SPARCV9:
    + return __get_dwarf_regstr(sparc_regstr_tbl, n);
    + case EM_XTENSA:
    + return __get_dwarf_regstr(xtensa_regstr_tbl, n);
    + default:
    + pr_err("ELF MACHINE %x is not supported.\n", machine);
    + }
    + return NULL;
    +}
    diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
    index 07c644e..43bfd8d 100644
    --- a/tools/perf/util/include/dwarf-regs.h
    +++ b/tools/perf/util/include/dwarf-regs.h
    @@ -3,6 +3,12 @@

    #ifdef HAVE_DWARF_SUPPORT
    const char *get_arch_regstr(unsigned int n);
    +/*
    + * get_dwarf_regstr - Returns ftrace register string from DWARF regnum
    + * n: DWARF register number
    + * machine: ELF machine signature (EM_*)
    + */
    +const char *get_dwarf_regstr(unsigned int n, unsigned int machine);
    #endif

    #ifdef HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET
    diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
    index ac4740f..508b61c 100644
    --- a/tools/perf/util/probe-finder.c
    +++ b/tools/perf/util/probe-finder.c
    @@ -171,6 +171,7 @@ static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
    */
    static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
    Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
    + unsigned int machine,
    struct probe_trace_arg *tvar)
    {
    Dwarf_Attribute attr;
    @@ -266,7 +267,7 @@ static_var:
    if (!tvar)
    return ret2;

    - regs = get_arch_regstr(regn);
    + regs = get_dwarf_regstr(regn, machine);
    if (!regs) {
    /* This should be a bug in DWARF or this tool */
    pr_warning("Mapping for the register number %u "
    @@ -543,7 +544,7 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
    dwarf_diename(vr_die));

    ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
    - &pf->sp_die, pf->tvar);
    + &pf->sp_die, pf->machine, pf->tvar);
    if (ret == -ENOENT || ret == -EINVAL) {
    pr_err("Failed to find the location of the '%s' variable at this address.\n"
    " Perhaps it has been optimized out.\n"
    @@ -1106,11 +1107,8 @@ static int debuginfo__find_probes(struct debuginfo *dbg,
    struct probe_finder *pf)
    {
    int ret = 0;
    -
    -#if _ELFUTILS_PREREQ(0, 142)
    Elf *elf;
    GElf_Ehdr ehdr;
    - GElf_Shdr shdr;

    if (pf->cfi_eh || pf->cfi_dbg)
    return debuginfo__find_probe_location(dbg, pf);
    @@ -1123,11 +1121,18 @@ static int debuginfo__find_probes(struct debuginfo *dbg,
    if (gelf_getehdr(elf, &ehdr) == NULL)
    return -EINVAL;

    - if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
    - shdr.sh_type == SHT_PROGBITS)
    - pf->cfi_eh = dwarf_getcfi_elf(elf);
    + pf->machine = ehdr.e_machine;
    +
    +#if _ELFUTILS_PREREQ(0, 142)
    + do {
    + GElf_Shdr shdr;
    +
    + if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
    + shdr.sh_type == SHT_PROGBITS)
    + pf->cfi_eh = dwarf_getcfi_elf(elf);

    - pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
    + pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
    + } while (0);
    #endif

    ret = debuginfo__find_probe_location(dbg, pf);
    @@ -1155,7 +1160,7 @@ static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
    (tag == DW_TAG_variable && vf->vars)) {
    if (convert_variable_location(die_mem, vf->pf->addr,
    vf->pf->fb_ops, &pf->sp_die,
    - NULL) == 0) {
    + pf->machine, NULL) == 0) {
    vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
    if (vf->args[vf->nargs].var == NULL) {
    vf->ret = -ENOMEM;
    @@ -1318,7 +1323,7 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
    tag == DW_TAG_variable) {
    ret = convert_variable_location(die_mem, af->pf.addr,
    af->pf.fb_ops, &af->pf.sp_die,
    - NULL);
    + af->pf.machine, NULL);
    if (ret == 0 || ret == -ERANGE) {
    int ret2;
    bool externs = !af->child;
    diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
    index 51137fc..f1d8558 100644
    --- a/tools/perf/util/probe-finder.h
    +++ b/tools/perf/util/probe-finder.h
    @@ -80,6 +80,7 @@ struct probe_finder {
    Dwarf_CFI *cfi_dbg;
    #endif
    Dwarf_Op *fb_ops; /* Frame base attribute */
    + unsigned int machine; /* Target machine arch */
    struct perf_probe_arg *pvar; /* Current target variable */
    struct probe_trace_arg *tvar; /* Current result variable */
    };
    \
     
     \ /
      Last update: 2016-09-17 09:57    [W:4.541 / U:0.004 seconds]
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