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objtool: Keep track of retpoline call sites 

Provide infrastructure for architectures to rewrite/augment compiler
generated retpoline calls. Similar to what we do for static_call()s,
keep track of the instructions that are retpoline calls.

Use the same list_head, since a retpoline call cannot also be a
static_call.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org
This commit is contained in:
Peter Zijlstra 2021-03-26 16:12:12 +01:00 committed by Ingo Molnar
parent 2f2f7e47f0
commit 43d5430ad7
5 changed files with 34 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
tools/objtool/check.c
View File

@ -451,7 +451,7 @@ static int create_static_call_sections(struct objtool_file *file)
return 0;
idx = 0;
list_for_each_entry(insn, &file->static_call_list, static_call_node)
list_for_each_entry(insn, &file->static_call_list, call_node)
idx++;
sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
@ -460,7 +460,7 @@ static int create_static_call_sections(struct objtool_file *file)
return -1;
idx = 0;
list_for_each_entry(insn, &file->static_call_list, static_call_node) {
list_for_each_entry(insn, &file->static_call_list, call_node) {
site = (struct static_call_site *)sec->data->d_buf + idx;
memset(site, 0, sizeof(struct static_call_site));
@ -829,13 +829,16 @@ static int add_jump_destinations(struct objtool_file *file)
else
insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
list_add_tail(&insn->call_node,
&file->retpoline_call_list);
insn->retpoline_safe = true;
continue;
} else if (insn->func) {
/* internal or external sibling call (with reloc) */
insn->call_dest = reloc->sym;
if (insn->call_dest->static_call_tramp) {
list_add_tail(&insn->static_call_node,
list_add_tail(&insn->call_node,
&file->static_call_list);
}
continue;
@ -897,7 +900,7 @@ static int add_jump_destinations(struct objtool_file *file)
/* internal sibling call (without reloc) */
insn->call_dest = insn->jump_dest->func;
if (insn->call_dest->static_call_tramp) {
list_add_tail(&insn->static_call_node,
list_add_tail(&insn->call_node,
&file->static_call_list);
}
}
@ -981,6 +984,9 @@ static int add_call_destinations(struct objtool_file *file)
insn->type = INSN_CALL_DYNAMIC;
insn->retpoline_safe = true;
list_add_tail(&insn->call_node,
&file->retpoline_call_list);
remove_insn_ops(insn);
continue;
@ -988,7 +994,7 @@ static int add_call_destinations(struct objtool_file *file)
insn->call_dest = reloc->sym;
if (insn->call_dest && insn->call_dest->static_call_tramp) {
list_add_tail(&insn->static_call_node,
list_add_tail(&insn->call_node,
&file->static_call_list);
}
@ -1714,6 +1720,11 @@ static void mark_rodata(struct objtool_file *file)
file->rodata = found;
}
__weak int arch_rewrite_retpolines(struct objtool_file *file)
{
return 0;
}
static int decode_sections(struct objtool_file *file)
{
int ret;
@ -1742,6 +1753,10 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
/*
* Must be before add_special_section_alts() as that depends on
* jump_dest being set.
*/
ret = add_jump_destinations(file);
if (ret)
return ret;
@ -1778,6 +1793,15 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
/*
* Must be after add_special_section_alts(), since this will emit
* alternatives. Must be after add_{jump,call}_destination(), since
* those create the call insn lists.
*/
ret = arch_rewrite_retpolines(file);
if (ret)
return ret;
return 0;
}

2
tools/objtool/include/objtool/arch.h
View File

@ -88,4 +88,6 @@ int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg);
bool arch_is_retpoline(struct symbol *sym);
int arch_rewrite_retpolines(struct objtool_file *file);
#endif /* _ARCH_H */

2
tools/objtool/include/objtool/check.h
View File

@ -39,7 +39,7 @@ struct alt_group {
struct instruction {
struct list_head list;
struct hlist_node hash;
struct list_head static_call_node;
struct list_head call_node;
struct list_head mcount_loc_node;
struct section *sec;
unsigned long offset;

1
tools/objtool/include/objtool/objtool.h
View File

@ -18,6 +18,7 @@ struct objtool_file {
struct elf *elf;
struct list_head insn_list;
DECLARE_HASHTABLE(insn_hash, 20);
struct list_head retpoline_call_list;
struct list_head static_call_list;
struct list_head mcount_loc_list;
bool ignore_unreachables, c_file, hints, rodata;

1
tools/objtool/objtool.c
View File

@ -61,6 +61,7 @@ struct objtool_file *objtool_open_read(const char *_objname)
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
INIT_LIST_HEAD(&file.retpoline_call_list);
INIT_LIST_HEAD(&file.static_call_list);
INIT_LIST_HEAD(&file.mcount_loc_list);
file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");