iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

objtool: Ignore exc_double_fault() __noreturn warnings

Browse Source 
This is a hack, but it works for now.

Problem is, exc_double_fault() may or may not return, depending on
whether CONFIG_X86_ESPFIX64 is set.  But objtool has no visibility to
the kernel config.

"Fix" it by silencing the exc_double_fault() __noreturn warning.

This removes the following warning:

  vmlinux.o: warning: objtool: xenpv_exc_double_fault+0xd: exc_double_fault() is missing a __noreturn annotation

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/a45b085071d3a7d049a20f9e78754452336ecbe8.1681853186.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf 2023-04-18 14:27:51 -07:00
parent fedb724c3d
commit 55eeab2a8a
1 changed files with 30 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
tools/objtool/check.c
View File

@ -4505,6 +4505,35 @@ static int validate_sls(struct objtool_file *file)
return warnings;
}
static bool ignore_noreturn_call(struct instruction *insn)
{
struct symbol *call_dest = insn_call_dest(insn);
/*
* FIXME: hack, we need a real noreturn solution
*
* Problem is, exc_double_fault() may or may not return, depending on
* whether CONFIG_X86_ESPFIX64 is set. But objtool has no visibility
* to the kernel config.
*
* Other potential ways to fix it:
*
* - have compiler communicate __noreturn functions somehow
* - remove CONFIG_X86_ESPFIX64
* - read the .config file
* - add a cmdline option
* - create a generic objtool annotation format (vs a bunch of custom
* formats) and annotate it
*/
if (!strcmp(call_dest->name, "exc_double_fault")) {
/* prevent further unreachable warnings for the caller */
insn->sym->warned = 1;
return true;
}
return false;
}
static int validate_reachable_instructions(struct objtool_file *file)
{
struct instruction *insn, *prev_insn;
@ -4521,7 +4550,7 @@ static int validate_reachable_instructions(struct objtool_file *file)
prev_insn = prev_insn_same_sec(file, insn);
if (prev_insn && prev_insn->dead_end) {
call_dest = insn_call_dest(prev_insn);
if (call_dest) {
if (call_dest && !ignore_noreturn_call(prev_insn)) {
WARN_INSN(insn, "%s() is missing a __noreturn annotation",
call_dest->name);
warnings++;