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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-12 20:44:24 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-12 20:44:24 +0300
commit87194efe7ecdf8d145c7cef130fda9652bf77fd7 (patch)
tree3df8089c58a7c967ab793ac63b337b9e75a3b8e7 /arch
parent9e536c817960c698c23feed6f9bff6d192805543 (diff)
parent1b9abd1755ad947d7c9913e92e7837b533124c90 (diff)
downloadlinux-87194efe7ecdf8d145c7cef130fda9652bf77fd7.tar.xz
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.S5
-rw-r--r--arch/x86/include/asm/fsgsbase.h4
-rw-r--r--arch/x86/kernel/process_64.c8
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