+ kfence-fix-reports-if-constant-function-prefixes-exist.patch added to -mm tree

+ kfence-fix-reports-if-constant-function-prefixes-exist.patch added to -mm tree

[akpm]

The patch titled
     Subject: kfence: fix reports if constant function prefixes exist
has been added to the -mm tree.  Its filename is
     kfence-fix-reports-if-constant-function-prefixes-exist.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/kfence-fix-reports-if-constant-function-prefixes-exist.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/kfence-fix-reports-if-constant-function-prefixes-exist.patch

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------------------------------------------------------
From: Marco Elver <elver@google.com>
Subject: kfence: fix reports if constant function prefixes exist

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
Link: https://lkml.kernel.org/r/20210304144000.1148590-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kfence/report.c |   18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

--- a/mm/kfence/report.c~kfence-fix-reports-if-constant-function-prefixes-exist
+++ a/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 unsign
 	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 unsign
 		}
 
 		/* 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)
_

Patches currently in -mm which might be from elver@google.com are

kfence-fix-printk-format-for-ptrdiff_t.patch
kfence-slab-fix-cache_alloc_debugcheck_after-for-bulk-allocations.patch
kfence-fix-reports-if-constant-function-prefixes-exist.patch