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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2022-03-14 14:49:36 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-04-05 10:59:38 +0300 |
| commit | 8fd4ddda2f49a66bf5dd3d0c01966c4b1971308b (patch) | |
| tree | ed31904efc09c25722b30768f54e11c026dad4bd /include/linux/static_call.h | |
| parent | 1cd5f059d956e6f614ba6666ecdbcf95db05d5f5 (diff) | |
| download | linux-8fd4ddda2f49a66bf5dd3d0c01966c4b1971308b.tar.xz | |
static_call: Don't make __static_call_return0 static
System.map shows that vmlinux contains several instances of
__static_call_return0():
c0004fc0 t __static_call_return0
c0011518 t __static_call_return0
c00d8160 t __static_call_return0
arch_static_call_transform() uses the middle one to check whether we are
setting a call to __static_call_return0 or not:
c0011520 <arch_static_call_transform>:
c0011520: 3d 20 c0 01 lis r9,-16383 <== r9 = 0xc001 << 16
c0011524: 39 29 15 18 addi r9,r9,5400 <== r9 += 0x1518
c0011528: 7c 05 48 00 cmpw r5,r9 <== r9 has value 0xc0011518 here
So if static_call_update() is called with one of the other instances of
__static_call_return0(), arch_static_call_transform() won't recognise it.
In order to work properly, global single instance of __static_call_return0() is required.
Fixes: 3f2a8fc4b15d ("static_call/x86: Add __static_call_return0()")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/30821468a0e7d28251954b578e5051dc09300d04.1647258493.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'include/linux/static_call.h')
| -rw-r--r-- | include/linux/static_call.h | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/include/linux/static_call.h b/include/linux/static_call.h index 3e56a9751c06..fcc5b48989b3 100644 --- a/include/linux/static_call.h +++ b/include/linux/static_call.h @@ -248,10 +248,7 @@ static inline int static_call_text_reserved(void *start, void *end) return 0; } -static inline long __static_call_return0(void) -{ - return 0; -} +extern long __static_call_return0(void); #define EXPORT_STATIC_CALL(name) \ EXPORT_SYMBOL(STATIC_CALL_KEY(name)); \ |