diff options
| 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 | |
| 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):
| -rw-r--r-- | include/asm-x86/system_32.h | 2 | ||||
| -rw-r--r-- | include/asm-x86/system_64.h | 8 |
2 files changed, 5 insertions, 5 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" diff --git a/include/asm-x86/system_64.h b/include/asm-x86/system_64.h index 5022aecc333d..fb4bcf99e665 100644 --- a/include/asm-x86/system_64.h +++ b/include/asm-x86/system_64.h @@ -85,7 +85,7 @@ static inline void write_cr0(unsigned long val) static inline unsigned long read_cr2(void) { unsigned long cr2; - asm("movq %%cr2,%0" : "=r" (cr2)); + asm volatile("movq %%cr2,%0" : "=r" (cr2)); return cr2; } @@ -97,7 +97,7 @@ static inline void write_cr2(unsigned long val) static inline unsigned long read_cr3(void) { unsigned long cr3; - asm("movq %%cr3,%0" : "=r" (cr3)); + asm volatile("movq %%cr3,%0" : "=r" (cr3)); return cr3; } @@ -109,7 +109,7 @@ static inline void write_cr3(unsigned long val) static inline unsigned long read_cr4(void) { unsigned long cr4; - asm("movq %%cr4,%0" : "=r" (cr4)); + asm volatile("movq %%cr4,%0" : "=r" (cr4)); return cr4; } @@ -121,7 +121,7 @@ static inline void write_cr4(unsigned long val) static inline unsigned long read_cr8(void) { unsigned long cr8; - asm("movq %%cr8,%0" : "=r" (cr8)); + asm volatile("movq %%cr8,%0" : "=r" (cr8)); return cr8; } |