Merge tag 'perf-core-for-mingo-20160901' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

User visible changes:

- Support generating cross arch probes, i.e. if you specify a vmlinux
  file for different arch than the one in the host machine,

	 $ perf probe --definition function_name args

  will generate the probe definition string needed to append to the
  target machine /sys/kernel/debug/tracing/kprobes_events file, using
  scripting (Masami Hiramatsu).

- Make 'perf probe' skip the function prologue in uprobes if program
  compiled without optimization, using the same strategy as gdb and
  systemtap uses, fixing a bug where:

	$ perf probe -x ./test 'foo i'

  When 'foo(42)' was used on the "./test" executable would produce i=0
  instead of the expected i=42 (Ravi Bangoria)

- Demangle symbols for synthesized @plt entries too (Millian Wolff)

Documentation changes:

- Show default report configuration in 'perf config' example
  and docs (Millian Wolff)

Infrastructure changes:

- Make 'perf test vmlinux' tolerate the symbol aliasing pruning done when
  loading kallsyms and vmlinux (Arnaldo Carvalho de Melo)

- Improve output of 'perf test vmlinux' test, to help identify on the verbose
  output which lines are warning and which are errors (Arnaldo Carvalho de Melo)

- Prep work to stop having to pass symbol_filter_t to lots of functions,
  simplifying symtab loading routines (Arnaldo Carvalho de Melo)

- Honor symbol_conf.allow_aliases when loading kallsyms as well, it was using
  it only when loading vmlinux files (Arnaldo Carvalho de Melo)

- Fixup symbol->end before doing alias pruning when loading symbol tables
  (Arnaldo Carvalho de Melo)

- Fix error handling of lzma kernel module decompression (Shawn Lin)

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 49 insertions, 11 deletions

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index ac4740f8ee3a..8daca4fc1f8d 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"
@@ -906,6 +907,38 @@ static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
 	return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
 }
 
+static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
+{
+	struct perf_probe_point *pp = &pf->pev->point;
+
+	/* Not uprobe? */
+	if (!pf->pev->uprobes)
+		return;
+
+	/* Compiled with optimization? */
+	if (die_is_optimized_target(&pf->cu_die))
+		return;
+
+	/* Don't know entrypc? */
+	if (!pf->addr)
+		return;
+
+	/* Only FUNC and FUNC@SRC are eligible. */
+	if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
+	    pp->offset || pp->abs_address)
+		return;
+
+	/* Not interested in func parameter? */
+	if (!perf_probe_with_var(pf->pev))
+		return;
+
+	pr_info("Target program is compiled without optimization. Skipping prologue.\n"
+		"Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
+		pf->addr);
+
+	die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
+}
+
 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
 {
 	struct probe_finder *pf = data;
@@ -968,6 +1001,7 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
 		if (pp->lazy_line)
 			param->retval = find_probe_point_lazy(sp_die, pf);
 		else {
+			skip_prologue(sp_die, pf);
 			pf->addr += pp->offset;
 			/* TODO: Check the address in this function */
 			param->retval = call_probe_finder(sp_die, pf);
@@ -1106,11 +1140,8 @@ 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 +1154,18 @@ 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 +1193,7 @@ 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 +1356,7 @@ 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;