[RFC PATCH 4/4] perf-probe: Support probing on offline cross-arch binary

Masami Hiramatsu
2016-08-24T05:58:56Z

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 */
};