Move the test for mcount symbols into the ELF code itself
and set a class on indicator on the symbol. This simplifies
mcount a little and tests the symbols names near where they're
first touched so should be cache-hot and may also help us
reduce the number of passes through the ELF contents needed
for individual subcommands. Finally, if we manage to combine
subcommands into a single exec of objtool the number of
passes through the ELF data could be even further reduced.
Suggested-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Matt Helsley <mhels...@vmware.com>
---
tools/objtool/elf.c | 18 ++++++++++++++++++
tools/objtool/elf.h | 6 ++++++
tools/objtool/mcount.c | 31 +++----------------------------
3 files changed, 27 insertions(+), 28 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 8dcdea8020a5..d55d8fef11b4 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -387,6 +387,21 @@ static int read_sections(struct elf *elf)
return 0;
}
+static bool is_mcount_sym(const char *name)
+{
+ if (name[0] == '.')
+ name++; /* ppc64 hack */
+
+ if (name[0] == '_')
+ name++;
+
+ if (strcmp("mcount", name) == 0 ||
+ (strcmp("__gnu_mcount_nc", name) == 0) ||
+ (strcmp("_fentry__", name) == 0))
+ return true;
+ return false;
+}
+
static int read_symbols(struct elf *elf)
{
struct section *symtab, *symtab_shndx, *sec;
@@ -456,6 +471,9 @@ static int read_symbols(struct elf *elf)
} else
sym->sec = find_section_by_index(elf, 0);
+ if (is_mcount_sym(sym->name))
+ sym->class = SYM_MCOUNT;
+
sym->offset = sym->sym.st_value;
sym->len = sym->sym.st_size;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 09fa0d085341..13935edaff54 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -42,6 +42,11 @@ struct section {
bool changed, text, rodata, noinstr;
};
+enum symbol_class {
+ SYM_REGULAR = 0,
+ SYM_MCOUNT = 1,
+};
+
struct symbol {
struct list_head list;
struct rb_node node;
@@ -55,6 +60,7 @@ struct symbol {
unsigned long offset;
unsigned int len;
struct symbol *pfunc, *cfunc, *alias;
+ enum symbol_class class;
bool uaccess_safe;
};
diff --git a/tools/objtool/mcount.c b/tools/objtool/mcount.c
index 029e6e72c972..7fbde6ce6eb8 100644
--- a/tools/objtool/mcount.c
+++ b/tools/objtool/mcount.c
@@ -152,24 +152,6 @@ static int is_mcounted_section_name(char const *const
txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
-static struct symbol *get_mcount_sym(struct reloc *reloc)
-{
- struct symbol *sym = reloc->sym;
- char const *symname = sym->name;
-
- if (symname[0] == '.')
- symname++; /* ppc64 hack */
-
- if (symname[0] == '_')
- symname++;
-
- if (strcmp("mcount", symname) == 0 ||
- (strcmp("__gnu_mcount_nc", symname) == 0) ||
- (strcmp("_fentry__", symname) == 0))
- return sym;
- return NULL;
-}
-
/*
* MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
* _mcount symbol is needed for dynamic function tracer, with it, to disable
@@ -266,16 +248,13 @@ static int nop_mcount(struct section * const rels,
{
struct reloc *reloc;
struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
- struct symbol *mcount_sym = NULL;
int once = 0;
list_for_each_entry(reloc, &rels->reloc_list, list) {
int ret = -1;
- if (!mcount_sym)
- mcount_sym = get_mcount_sym(reloc);
-
- if (mcount_sym == reloc->sym && !is_fake_mcount(reloc)) {
+ if (reloc->sym->class == SYM_MCOUNT &&
+ !is_fake_mcount(reloc)) {
if (make_nop) {
ret = make_nop(txts, reloc->offset);
if (ret < 0)
@@ -355,16 +334,12 @@ static void sift_rel_mcount(GElf_Addr **mlocpp,
{
GElf_Rel *mrelp = *mrelpp;
GElf_Rela *mrelap = *mrelpp;
- struct symbol *mcount_sym = NULL;
struct reloc *reloc;
list_for_each_entry(reloc, &rels->reloc_list, list) {
unsigned long addend;
- if (!mcount_sym)
- mcount_sym = get_mcount_sym(reloc);
-
- if (mcount_sym != reloc->sym || is_fake_mcount(reloc))
+ if (reloc->sym->class == SYM_MCOUNT || is_fake_mcount(reloc))
continue;
addend = reloc->offset - recval + mcount_adjust;
--
2.20.1
