6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
[ Upstream commit 10f4c9b9a33b7df000f74fa0d896351fb1a61e6a ]
Building UML with KASAN fails since commit 69d4c0d32186 ("entry, kasan,
x86: Disallow overriding mem*() functions") with the following errors:
$ tools/testing/kunit/kunit.py run --kconfig_add CONFIG_KASAN=y
...
ld: mm/kasan/shadow.o: in function `memset':
shadow.c:(.text+0x40): multiple definition of `memset';
arch/x86/lib/memset_64.o:(.noinstr.text+0x0): first defined here
ld: mm/kasan/shadow.o: in function `memmove':
shadow.c:(.text+0x90): multiple definition of `memmove';
arch/x86/lib/memmove_64.o:(.noinstr.text+0x0): first defined here
ld: mm/kasan/shadow.o: in function `memcpy':
shadow.c:(.text+0x110): multiple definition of `memcpy';
arch/x86/lib/memcpy_64.o:(.noinstr.text+0x0): first defined here
UML does not use GENERIC_ENTRY and is still supposed to be allowed to
override the mem*() functions, so use weak aliases in that case.
Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230918-uml-kasan-v3-1-7ad6db477df6@xxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/include/asm/linkage.h | 7 +++++++
arch/x86/lib/memcpy_64.S | 2 +-
arch/x86/lib/memmove_64.S | 2 +-
arch/x86/lib/memset_64.S | 2 +-
4 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h
index 5ff49fd67732e..571fe4d2d2328 100644
--- a/arch/x86/include/asm/linkage.h
+++ b/arch/x86/include/asm/linkage.h
@@ -105,6 +105,13 @@
CFI_POST_PADDING \
SYM_FUNC_END(__cfi_##name)
+/* UML needs to be able to override memcpy() and friends for KASAN. */
+#ifdef CONFIG_UML
+# define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS_WEAK
+#else
+# define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS
+#endif
+
/* SYM_TYPED_FUNC_START -- use for indirectly called globals, w/ CFI type */
#define SYM_TYPED_FUNC_START(name) \
SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_F_ALIGN) \
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 8f95fb267caa7..76697df8dfd5b 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -40,7 +40,7 @@ SYM_TYPED_FUNC_START(__memcpy)
SYM_FUNC_END(__memcpy)
EXPORT_SYMBOL(__memcpy)
-SYM_FUNC_ALIAS(memcpy, __memcpy)
+SYM_FUNC_ALIAS_MEMFUNC(memcpy, __memcpy)
EXPORT_SYMBOL(memcpy)
SYM_FUNC_START_LOCAL(memcpy_orig)
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index 0559b206fb110..ccdf3a597045e 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -212,5 +212,5 @@ SYM_FUNC_START(__memmove)
SYM_FUNC_END(__memmove)
EXPORT_SYMBOL(__memmove)
-SYM_FUNC_ALIAS(memmove, __memmove)
+SYM_FUNC_ALIAS_MEMFUNC(memmove, __memmove)
EXPORT_SYMBOL(memmove)
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 7c59a704c4584..3d818b849ec64 100644
--- a/arch/x86/lib/memset_64.S
+++ b/arch/x86/lib/memset_64.S
@@ -40,7 +40,7 @@ SYM_FUNC_START(__memset)
SYM_FUNC_END(__memset)
EXPORT_SYMBOL(__memset)
-SYM_FUNC_ALIAS(memset, __memset)
+SYM_FUNC_ALIAS_MEMFUNC(memset, __memset)
EXPORT_SYMBOL(memset)
SYM_FUNC_START_LOCAL(memset_orig)
--
2.40.1
