diff options
| author | Linus Torvalds <torvalds@home.transmeta.com> | 2003-03-09 02:49:41 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@home.transmeta.com> | 2003-03-09 02:49:41 -0800 |
| commit | 36f0619922472bf8e5ecf83ac420114952a87bf3 (patch) | |
| tree | 65effd9c155da6774b45ddb3ab23e9f23add6098 /include | |
| parent | d1537fd1c7a1fa9303467825eb5a764cb229df10 (diff) | |
Cache the MSR_IA32_SYSENTER_CS value in the per-CPU TSS (using
the otherwise unused cpl1 entry for SS), so that we can avoid
re-loading it on task switches if it doesn't change.
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-i386/processor.h | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index 5ed85117e7ef..00014406c6ac 100644 --- a/include/asm-i386/processor.h +++ b/include/asm-i386/processor.h @@ -347,7 +347,7 @@ struct tss_struct { unsigned long esp0; unsigned short ss0,__ss0h; unsigned long esp1; - unsigned short ss1,__ss1h; + unsigned short ss1,__ss1h; /* ss1 is used to cache MSR_IA32_SYSENTER_CS */ unsigned long esp2; unsigned short ss2,__ss2h; unsigned long __cr3; @@ -413,15 +413,20 @@ static inline void load_esp0(struct tss_struct *tss, unsigned long esp0) { tss->esp0 = esp0; if (cpu_has_sep) { - wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0); + if (tss->ss1 != __KERNEL_CS) { + tss->ss1 = __KERNEL_CS; + wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0); + } wrmsr(MSR_IA32_SYSENTER_ESP, esp0, 0); } } -static inline void disable_sysenter(void) +static inline void disable_sysenter(struct tss_struct *tss) { - if (cpu_has_sep) + if (cpu_has_sep) { + tss->ss1 = 0; wrmsr(MSR_IA32_SYSENTER_CS, 0, 0); + } } #define start_thread(regs, new_eip, new_esp) do { \ |