diff mbox series

[mm] kfence: fix reports if constant function prefixes exist

Message ID 20210304144000.1148590-1-elver@google.com (mailing list archive)
State New
Headers show
Series [mm] kfence: fix reports if constant function prefixes exist | expand

Commit Message

Marco Elver March 4, 2021, 2:40 p.m. UTC
Some architectures prefix all functions with a constant string ('.' on
ppc64). Add ARCH_FUNC_PREFIX, which may optionally be defined in
<asm/kfence.h>, so that get_stack_skipnr() can work properly.

Link: https://lkml.kernel.org/r/f036c53d-7e81-763c-47f4-6024c6c5f058@csgroup.eu
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Marco Elver <elver@google.com>
---
 mm/kfence/report.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

Comments

Marco Elver March 4, 2021, 2:43 p.m. UTC | #1
On Thu, 4 Mar 2021 at 15:40, Marco Elver <elver@google.com> wrote:
> Some architectures prefix all functions with a constant string ('.' on
> ppc64). Add ARCH_FUNC_PREFIX, which may optionally be defined in
> <asm/kfence.h>, so that get_stack_skipnr() can work properly.
>
> Link: https://lkml.kernel.org/r/f036c53d-7e81-763c-47f4-6024c6c5f058@csgroup.eu
> Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> Signed-off-by: Marco Elver <elver@google.com>
> ---

For further context, the corresponding ppc64-enablement patch is was
just sent by Christophe:

  https://lkml.kernel.org/r/afaec81a551ef15345cb7d7563b3fac3d7041c3a.1614868445.git.christophe.leroy@csgroup.eu

But there is no strict dependency between the patches, only that the
stack traces that KFENCE prints aren't as pretty without the
ARCH_FUNC_PREFIX patch.

So it should be fine to take them through different trees, as long as
they both make the next merge window.

Thanks,
-- Marco
diff mbox series

Patch

diff --git a/mm/kfence/report.c b/mm/kfence/report.c
index 519f037720f5..e3f71451ad9e 100644
--- a/mm/kfence/report.c
+++ b/mm/kfence/report.c
@@ -20,6 +20,11 @@ 
 
 #include "kfence.h"
 
+/* May be overridden by <asm/kfence.h>. */
+#ifndef ARCH_FUNC_PREFIX
+#define ARCH_FUNC_PREFIX ""
+#endif
+
 extern bool no_hash_pointers;
 
 /* Helper function to either print to a seq_file or to console. */
@@ -67,8 +72,9 @@  static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
 	for (skipnr = 0; skipnr < num_entries; skipnr++) {
 		int len = scnprintf(buf, sizeof(buf), "%ps", (void *)stack_entries[skipnr]);
 
-		if (str_has_prefix(buf, "kfence_") || str_has_prefix(buf, "__kfence_") ||
-		    !strncmp(buf, "__slab_free", len)) {
+		if (str_has_prefix(buf, ARCH_FUNC_PREFIX "kfence_") ||
+		    str_has_prefix(buf, ARCH_FUNC_PREFIX "__kfence_") ||
+		    !strncmp(buf, ARCH_FUNC_PREFIX "__slab_free", len)) {
 			/*
 			 * In case of tail calls from any of the below
 			 * to any of the above.
@@ -77,10 +83,10 @@  static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
 		}
 
 		/* Also the *_bulk() variants by only checking prefixes. */
-		if (str_has_prefix(buf, "kfree") ||
-		    str_has_prefix(buf, "kmem_cache_free") ||
-		    str_has_prefix(buf, "__kmalloc") ||
-		    str_has_prefix(buf, "kmem_cache_alloc"))
+		if (str_has_prefix(buf, ARCH_FUNC_PREFIX "kfree") ||
+		    str_has_prefix(buf, ARCH_FUNC_PREFIX "kmem_cache_free") ||
+		    str_has_prefix(buf, ARCH_FUNC_PREFIX "__kmalloc") ||
+		    str_has_prefix(buf, ARCH_FUNC_PREFIX "kmem_cache_alloc"))
 			goto found;
 	}
 	if (fallback < num_entries)