Le 22/06/2023 à 13:56, Peter Zijlstra a écrit :
> On Thu, Jun 22, 2023 at 12:54:36PM +0200, Christophe Leroy wrote:
>
>> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
>> index f850ab892ad5..8ac5711a055f 100644
>> --- a/tools/objtool/check.c
>> +++ b/tools/objtool/check.c
>> @@ -218,6 +218,7 @@ static bool __dead_end_function(struct objtool_file
>> *file, struct symbol *func,
>> "kthread_exit",
>> "kunit_try_catch_throw",
>> "lbug_with_loc",
>> + "longjmp",
>> "machine_real_restart",
>> "make_task_dead",
>> "mpt_halt_firmware",
>> @@ -230,7 +231,9 @@ static bool __dead_end_function(struct objtool_file
>> *file, struct symbol *func,
>> "sev_es_terminate",
>> "snp_abort",
>> "start_kernel",
>> + "start_secondary_resume",
>> "stop_this_cpu",
>> + "unrecoverable_exception",
>> "usercopy_abort",
>> "x86_64_start_kernel",
>> "x86_64_start_reservations",
>
> Someone went and changed all that in tip/objtool/core :-)
>
> But perhaps, like the uaccess_safe_builtins[] array below, should we
> start marking sections so we can remember where stuff comes from later?
Or, now that it is a H file, maybe each arch could have its own H file
for arch specific functions ? Then we'd get:
diff --git a/tools/objtool/arch/powerpc/include/arch/noreturns.h
b/tools/objtool/arch/powerpc/include/arch/noreturns.h
new file mode 100644
index 000000000000..664f17d39026
--- /dev/null
+++ b/tools/objtool/arch/powerpc/include/arch/noreturns.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * This is a (sorted!) list of all known __noreturn functions in
arch/powerpc.
+ * It's needed for objtool to properly reverse-engineer the control
flow graph.
+ *
+ * Yes, this is unfortunate. A better solution is in the works.
+ */
+NORETURN(longjmp)
+NORETURN(start_secondary_resume)
+NORETURN(unrecoverable_exception)
diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h
index 1514e84d5cc4..f725ed37532d 100644
--- a/tools/objtool/noreturns.h
+++ b/tools/objtool/noreturns.h
@@ -1,5 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */
+#include <arch/noreturns.h>
+
/*
* This is a (sorted!) list of all known __noreturn functions in the
kernel.
* It's needed for objtool to properly reverse-engineer the control
flow graph.
>
>> @@ -1335,6 +1338,8 @@ static const char *uaccess_safe_builtin[] = {
>> "rep_stos_alternative",
>> "rep_movs_alternative",
>> "__copy_user_nocache",
>> + "__copy_tofrom_user",
>> + "__arch_clear_user",
>> NULL
>> };
>
> Do we want to rename the 'misc' sectino to 'x86' and start a 'ppc32'
> section there?
>
Sure.
Then that would look like:
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2b61f8180bea..2d564d0e2ae1 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1259,13 +1259,15 @@ static const char *uaccess_safe_builtin[] = {
"stackleak_track_stack",
/* misc */
"csum_partial_copy_generic",
+ "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
+ /* misc x86 */
"copy_mc_fragile",
"copy_mc_fragile_handle_tail",
"copy_mc_enhanced_fast_string",
- "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
"rep_stos_alternative",
"rep_movs_alternative",
"__copy_user_nocache",
+ /* misc powerpc */
"__copy_tofrom_user",
"__arch_clear_user",
NULL
