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Message-ID: <20160831205411.GB13095@kernel.org>
Date:   Wed, 31 Aug 2016 17:54:11 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH v2 3/3] perf-probe: Support probing on offline cross-arch
 binary

Em Fri, Aug 26, 2016 at 01:24:57AM +0900, Masami Hiramatsu escreveu:
> 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:
>   -----
>   $ perf probe --vmlinux=./vmlinux-arm --definition 'do_sys_open $params'
>   p:probe/do_sys_open do_sys_open+0 dfd=%r5:s32 filename=%r1:u32 flags=%r6:s32 mode=%r3:u16
>   -----
> Here, we can get probe/do_sys_open event by "copy & paste" from
> ./tracing/kprobe_events to target-machine's debugfs/tracing/kprobe_events

Fixing the example not to refer to "tracing/kprobe_events", as it is not
there anymore, instead append what '--definition' produced to the target
machine <tracefs mountpoint>/tracing/kprobe_events file.

- Arnaldo
 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>   Changes from v1:
>    - Change the example.
> ---
>  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@...nel.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 */
>  };

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