Hand-written asm often contains non-function symbols in executable
sections. _end symbols for finding the size of instruction blocks
for runtime processing is one such usage.
optprobe_template_end is one example that causes the warning:
objtool: optprobe_template_end(): can't find starting instruction
This is because the symbol happens to be at the end of the file (and
therefore end of a section in the object file).
So ignore end-of-section STT_NOTYPE symbols instead of bailing out
because an instruction can't be found. While we're here, add a more
descriptive warning for STT_FUNC symbols found at the end of a
section.
Signed-off-by: Nicholas Piggin <[email protected]>
---
tools/objtool/check.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4350be739f4f..4b7c8b33069e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -427,6 +427,15 @@ static int decode_instructions(struct objtool_file *file)
if (func->type != STT_NOTYPE && func->type != STT_FUNC)
continue;
+ if (func->offset == sec->sh.sh_size) {
+ /* Heuristic: likely an "end" symbol */
+ if (func->type == STT_NOTYPE)
+ continue;
+ WARN("%s(): STT_FUNC at end of section",
+ func->name);
+ return -1;
+ }
+
if (func->return_thunk || func->alias != func)
continue;
--
2.37.2
Le 20/12/2022 à 11:13, Nicholas Piggin a écrit :
> Hand-written asm often contains non-function symbols in executable
> sections. _end symbols for finding the size of instruction blocks
> for runtime processing is one such usage.
>
> optprobe_template_end is one example that causes the warning:
>
> objtool: optprobe_template_end(): can't find starting instruction
>
> This is because the symbol happens to be at the end of the file (and
> therefore end of a section in the object file).
>
> So ignore end-of-section STT_NOTYPE symbols instead of bailing out
> because an instruction can't be found. While we're here, add a more
> descriptive warning for STT_FUNC symbols found at the end of a
> section.
There's a patch to solve this already as far as I understand. They seem
different.
See
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/[email protected]/
>
> Signed-off-by: Nicholas Piggin <[email protected]>
> ---
> tools/objtool/check.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 4350be739f4f..4b7c8b33069e 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -427,6 +427,15 @@ static int decode_instructions(struct objtool_file *file)
> if (func->type != STT_NOTYPE && func->type != STT_FUNC)
> continue;
>
> + if (func->offset == sec->sh.sh_size) {
> + /* Heuristic: likely an "end" symbol */
> + if (func->type == STT_NOTYPE)
> + continue;
> + WARN("%s(): STT_FUNC at end of section",
> + func->name);
> + return -1;
> + }
> +
> if (func->return_thunk || func->alias != func)
> continue;
>
The following commit has been merged into the core/urgent branch of tip:
Commit-ID: cad90e5381d840cf2296aaac9b3eff71a30b7c5b
Gitweb: https://git.kernel.org/tip/cad90e5381d840cf2296aaac9b3eff71a30b7c5b
Author: Nicholas Piggin <[email protected]>
AuthorDate: Tue, 20 Dec 2022 20:13:23 +10:00
Committer: Ingo Molnar <[email protected]>
CommitterDate: Mon, 09 Jan 2023 17:53:46 +01:00
objtool: Tolerate STT_NOTYPE symbols at end of section
Hand-written asm often contains non-function symbols in executable
sections. _end symbols for finding the size of instruction blocks
for runtime processing is one such usage.
optprobe_template_end is one example that causes the warning:
objtool: optprobe_template_end(): can't find starting instruction
This is because the symbol happens to be at the end of the file (and
therefore end of a section in the object file).
So ignore end-of-section STT_NOTYPE symbols instead of bailing out
because an instruction can't be found. While we're here, add a more
descriptive warning for STT_FUNC symbols found at the end of a
section.
[ This also solves a PowerPC regression reported by Sathvika Vasireddy. ]
Reported-by: Naveen N. Rao <[email protected]>
Reported-by: Sathvika Vasireddy <[email protected]>
Signed-off-by: Nicholas Piggin <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Sathvika Vasireddy <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
tools/objtool/check.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4350be7..4b7c8b3 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -427,6 +427,15 @@ static int decode_instructions(struct objtool_file *file)
if (func->type != STT_NOTYPE && func->type != STT_FUNC)
continue;
+ if (func->offset == sec->sh.sh_size) {
+ /* Heuristic: likely an "end" symbol */
+ if (func->type == STT_NOTYPE)
+ continue;
+ WARN("%s(): STT_FUNC at end of section",
+ func->name);
+ return -1;
+ }
+
if (func->return_thunk || func->alias != func)
continue;