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objtool: Explicitly avoid self modifying code in .altinstr_replacement

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Assume ALTERNATIVE()s know what they're doing and do not change, or
cause to change, instructions in .altinstr_replacement sections.

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/20211026120309.722511775@infradead.org
This commit is contained in:
Peter Zijlstra 2021-10-26 14:01:34 +02:00
parent 1739c66eb7
commit dd003edeff
1 changed files with 31 additions and 11 deletions
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42
tools/objtool/check.c
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@ -993,18 +993,27 @@ static void remove_insn_ops(struct instruction *insn)
}
}
static void add_call_dest(struct objtool_file *file, struct instruction *insn,
struct symbol *dest, bool sibling)
static void annotate_call_site(struct objtool_file *file,
struct instruction *insn, bool sibling)
{
struct reloc *reloc = insn_reloc(file, insn);
struct symbol *sym = insn->call_dest;
insn->call_dest = dest;
if (!dest)
if (!sym)
sym = reloc->sym;
/*
* Alternative replacement code is just template code which is
* sometimes copied to the original instruction. For now, don't
* annotate it. (In the future we might consider annotating the
* original instruction if/when it ever makes sense to do so.)
*/
if (!strcmp(insn->sec->name, ".altinstr_replacement"))
return;
if (insn->call_dest->static_call_tramp) {
list_add_tail(&insn->call_node,
&file->static_call_list);
if (sym->static_call_tramp) {
list_add_tail(&insn->call_node, &file->static_call_list);
return;
}
/*
@ -1012,7 +1021,7 @@ static void add_call_dest(struct objtool_file *file, struct instruction *insn,
* so they need a little help, NOP out any KCOV calls from noinstr
* text.
*/
if (insn->sec->noinstr && insn->call_dest->kcov) {
if (insn->sec->noinstr && sym->kcov) {
if (reloc) {
reloc->type = R_NONE;
elf_write_reloc(file->elf, reloc);
@ -1024,9 +1033,10 @@ static void add_call_dest(struct objtool_file *file, struct instruction *insn,
: arch_nop_insn(insn->len));
insn->type = sibling ? INSN_RETURN : INSN_NOP;
return;
}
if (mcount && insn->call_dest->fentry) {
if (mcount && sym->fentry) {
if (sibling)
WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
@ -1041,9 +1051,17 @@ static void add_call_dest(struct objtool_file *file, struct instruction *insn,
insn->type = INSN_NOP;
list_add_tail(&insn->mcount_loc_node,
&file->mcount_loc_list);
list_add_tail(&insn->mcount_loc_node, &file->mcount_loc_list);
return;
}
}
static void add_call_dest(struct objtool_file *file, struct instruction *insn,
struct symbol *dest, bool sibling)
{
insn->call_dest = dest;
if (!dest)
return;
/*
* Whatever stack impact regular CALLs have, should be undone
@ -1053,6 +1071,8 @@ static void add_call_dest(struct objtool_file *file, struct instruction *insn,
* are converted to JUMP, see read_intra_function_calls().
*/
remove_insn_ops(insn);
annotate_call_site(file, insn, sibling);
}
/*