diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-12 10:44:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-12 10:44:24 -0700 |
| commit | 87194efe7ecdf8d145c7cef130fda9652bf77fd7 (patch) | |
| tree | 3df8089c58a7c967ab793ac63b337b9e75a3b8e7 /arch | |
| parent | 9e536c817960c698c23feed6f9bff6d192805543 (diff) | |
| parent | 1b9abd1755ad947d7c9913e92e7837b533124c90 (diff) | |
Merge tag 'x86_fsgsbase_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fsgsbase updates from Borislav Petkov:
"Misc minor cleanups and corrections to the fsgsbase code and
respective selftests"
* tag 'x86_fsgsbase_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
selftests/x86/fsgsbase: Test PTRACE_PEEKUSER for GSBASE with invalid LDT GS
selftests/x86/fsgsbase: Reap a forgotten child
x86/fsgsbase: Replace static_cpu_has() with boot_cpu_has()
x86/entry/64: Correct the comment over SAVE_AND_SET_GSBASE
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 5 | ||||
| -rw-r--r-- | arch/x86/include/asm/fsgsbase.h | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/process_64.c | 8 |
3 files changed, 9 insertions, 8 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index d977079a7d02..748c2db3c54e 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -842,8 +842,9 @@ SYM_CODE_START_LOCAL(paranoid_entry) * retrieve and set the current CPUs kernel GSBASE. The stored value * has to be restored in paranoid_exit unconditionally. * - * The MSR write ensures that no subsequent load is based on a - * mispredicted GSBASE. No extra FENCE required. + * The unconditional write to GS base below ensures that no subsequent + * loads based on a mispredicted GS base can happen, therefore no LFENCE + * is needed here. */ SAVE_AND_SET_GSBASE scratch_reg=%rax save_reg=%rbx ret diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h index d552646411a9..35cff5f2becf 100644 --- a/arch/x86/include/asm/fsgsbase.h +++ b/arch/x86/include/asm/fsgsbase.h @@ -57,7 +57,7 @@ static inline unsigned long x86_fsbase_read_cpu(void) { unsigned long fsbase; - if (static_cpu_has(X86_FEATURE_FSGSBASE)) + if (boot_cpu_has(X86_FEATURE_FSGSBASE)) fsbase = rdfsbase(); else rdmsrl(MSR_FS_BASE, fsbase); @@ -67,7 +67,7 @@ static inline unsigned long x86_fsbase_read_cpu(void) static inline void x86_fsbase_write_cpu(unsigned long fsbase) { - if (static_cpu_has(X86_FEATURE_FSGSBASE)) + if (boot_cpu_has(X86_FEATURE_FSGSBASE)) wrfsbase(fsbase); else wrmsrl(MSR_FS_BASE, fsbase); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 9afefe325acb..df342bedea88 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -407,7 +407,7 @@ unsigned long x86_gsbase_read_cpu_inactive(void) { unsigned long gsbase; - if (static_cpu_has(X86_FEATURE_FSGSBASE)) { + if (boot_cpu_has(X86_FEATURE_FSGSBASE)) { unsigned long flags; local_irq_save(flags); @@ -422,7 +422,7 @@ unsigned long x86_gsbase_read_cpu_inactive(void) void x86_gsbase_write_cpu_inactive(unsigned long gsbase) { - if (static_cpu_has(X86_FEATURE_FSGSBASE)) { + if (boot_cpu_has(X86_FEATURE_FSGSBASE)) { unsigned long flags; local_irq_save(flags); @@ -439,7 +439,7 @@ unsigned long x86_fsbase_read_task(struct task_struct *task) if (task == current) fsbase = x86_fsbase_read_cpu(); - else if (static_cpu_has(X86_FEATURE_FSGSBASE) || + else if (boot_cpu_has(X86_FEATURE_FSGSBASE) || (task->thread.fsindex == 0)) fsbase = task->thread.fsbase; else @@ -454,7 +454,7 @@ unsigned long x86_gsbase_read_task(struct task_struct *task) if (task == current) gsbase = x86_gsbase_read_cpu_inactive(); - else if (static_cpu_has(X86_FEATURE_FSGSBASE) || + else if (boot_cpu_has(X86_FEATURE_FSGSBASE) || (task->thread.gsindex == 0)) gsbase = task->thread.gsbase; else |