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| author | Kirill Korotaev | 2007-10-17 18:04:33 +0200 |
|---|---|---|
| committer | Thomas Gleixner | 2007-10-17 20:15:31 +0200 |
| commit | c1217a75ea102d4e69321f210fab60bc47b9a48e (patch) | |
| tree | fffa575916b27bac17dfb751300ed2e1f9107f0c /include/asm-x86/system_32.h | |
| parent | x86: initialize 64bit registers for a.out executables (diff) | |
| download | kernel-qcow2-linux-c1217a75ea102d4e69321f210fab60bc47b9a48e.tar.gz kernel-qcow2-linux-c1217a75ea102d4e69321f210fab60bc47b9a48e.tar.xz kernel-qcow2-linux-c1217a75ea102d4e69321f210fab60bc47b9a48e.zip | |
x86: mark read_crX() asm code as volatile
Some gcc versions (I checked at least 4.1.1 from RHEL5 & 4.1.2 from gentoo)
can generate incorrect code with read_crX()/write_crX() functions mix up,
due to cached results of read_crX().
The small app for x8664 below compiled with -O2 demonstrates this
(i686 does the same thing):
Diffstat (limited to 'include/asm-x86/system_32.h')
| -rw-r--r-- | include/asm-x86/system_32.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-x86/system_32.h b/include/asm-x86/system_32.h index d84e593b7dfc..1d6fb3afa533 100644 --- a/include/asm-x86/system_32.h +++ b/include/asm-x86/system_32.h @@ -142,7 +142,7 @@ static inline unsigned long native_read_cr4_safe(void) { unsigned long val; /* This could fault if %cr4 does not exist */ - asm("1: movl %%cr4, %0 \n" + asm volatile("1: movl %%cr4, %0 \n" "2: \n" ".section __ex_table,\"a\" \n" ".long 1b,2b \n" |