[PATCH 5.10 047/130] objtool: Classify symbols

Greg Kroah-Hartman
2022-07-12T18:50:34Z

commit 1739c66eb7bd5f27f1b69a5a26e10e8327d1e136 upstream.

In order to avoid calling str*cmp() on symbol names, over and over, do
them all once upfront and store the result.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.658539311@infradead.org
[cascardo: no pv_target on struct symbol, because of missing
db2b0c5d7b6f19b3c2cab08c531b65342eb5252b]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
[bwh: Backported to 5.10: objtool doesn't have any mcount handling]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/objtool/check.c | 32 +++++++++++++++++++++-----------
tools/objtool/elf.h | 7 +++++--
2 files changed, 26 insertions(+), 13 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -889,8 +889,7 @@ static void add_call_dest(struct objtool
* so they need a little help, NOP out any KCOV calls from noinstr
* text.
*/
- if (insn->sec->noinstr &&
- !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {
+ if (insn->sec->noinstr && insn->call_dest->kcov) {
if (reloc) {
reloc->type = R_NONE;
elf_write_reloc(file->elf, reloc);
@@ -935,7 +934,7 @@ static int add_jump_destinations(struct
} else if (reloc->sym->type == STT_SECTION) {
dest_sec = reloc->sym->sec;
dest_off = arch_dest_reloc_offset(reloc->addend);
- } else if (arch_is_retpoline(reloc->sym)) {
+ } else if (reloc->sym->retpoline_thunk) {
/*
* Retpoline jumps are really dynamic jumps in
* disguise, so convert them accordingly.
@@ -1076,7 +1075,7 @@ static int add_call_destinations(struct

add_call_dest(file, insn, dest, false);

- } else if (arch_is_retpoline(reloc->sym)) {
+ } else if (reloc->sym->retpoline_thunk) {
/*
* Retpoline calls are really dynamic calls in
* disguise, so convert them accordingly.
@@ -1733,17 +1732,28 @@ static int read_intra_function_calls(str
return 0;
}

-static int read_static_call_tramps(struct objtool_file *file)
+static int classify_symbols(struct objtool_file *file)
{
struct section *sec;
struct symbol *func;

for_each_sec(file, sec) {
list_for_each_entry(func, &sec->symbol_list, list) {
- if (func->bind == STB_GLOBAL &&
- !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
+ if (func->bind != STB_GLOBAL)
+ continue;
+
+ if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
func->static_call_tramp = true;
+
+ if (arch_is_retpoline(func))
+ func->retpoline_thunk = true;
+
+ if (!strcmp(func->name, "__fentry__"))
+ func->fentry = true;
+
+ if (!strncmp(func->name, "__sanitizer_cov_", 16))
+ func->kcov = true;
}
}

@@ -1805,7 +1815,7 @@ static int decode_sections(struct objtoo
/*
* Must be before add_{jump_call}_destination.
*/
- ret = read_static_call_tramps(file);
+ ret = classify_symbols(file);
if (ret)
return ret;

@@ -1863,9 +1873,9 @@ static int decode_sections(struct objtoo

static bool is_fentry_call(struct instruction *insn)
{
- if (insn->type == INSN_CALL && insn->call_dest &&
- insn->call_dest->type == STT_NOTYPE &&
- !strcmp(insn->call_dest->name, "__fentry__"))
+ if (insn->type == INSN_CALL &&
+ insn->call_dest &&
+ insn->call_dest->fentry)
return true;

return false;
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -55,8 +55,11 @@ struct symbol {
unsigned long offset;
unsigned int len;
struct symbol *pfunc, *cfunc, *alias;
- bool uaccess_safe;
- bool static_call_tramp;
+ u8 uaccess_safe : 1;
+ u8 static_call_tramp : 1;
+ u8 retpoline_thunk : 1;
+ u8 fentry : 1;
+ u8 kcov : 1;
};

struct reloc {