The following commit has been merged into the x86/core branch of tip:
Commit-ID: e836c9cd89d097603e80a1a0d1c90d887f573129
Gitweb: https://git.kernel.org/tip/e836c9cd89d097603e80a1a0d1c90d887f573129
Author: Brian Gerst <brgerst@xxxxxxxxx>
AuthorDate: Mon, 03 Mar 2025 11:52:40 -05:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Mon, 03 Mar 2025 21:37:41 +01:00
x86/retbleed: Move call depth to percpu hot section
No functional change.
Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250303165246.2175811-6-brgerst@xxxxxxxxx
---
arch/x86/include/asm/current.h | 3 ---
arch/x86/include/asm/nospec-branch.h | 11 ++++++-----
arch/x86/kernel/asm-offsets.c | 3 ---
arch/x86/kernel/cpu/common.c | 8 ++++++++
arch/x86/lib/retpoline.S | 2 +-
5 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h
index f988462..8ba2c0f 100644
--- a/arch/x86/include/asm/current.h
+++ b/arch/x86/include/asm/current.h
@@ -14,9 +14,6 @@ struct task_struct;
struct pcpu_hot {
struct task_struct *current_task;
-#ifdef CONFIG_MITIGATION_CALL_DEPTH_TRACKING
- u64 call_depth;
-#endif
unsigned long top_of_stack;
void *hardirq_stack_ptr;
u16 softirq_pending;
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 7e8bf78..a560205 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -12,7 +12,6 @@
#include <asm/msr-index.h>
#include <asm/unwind_hints.h>
#include <asm/percpu.h>
-#include <asm/current.h>
/*
* Call depth tracking for Intel SKL CPUs to address the RSB underflow
@@ -78,21 +77,21 @@
#include <asm/asm-offsets.h>
#define CREDIT_CALL_DEPTH \
- movq $-1, PER_CPU_VAR(pcpu_hot + X86_call_depth);
+ movq $-1, PER_CPU_VAR(__x86_call_depth);
#define RESET_CALL_DEPTH \
xor %eax, %eax; \
bts $63, %rax; \
- movq %rax, PER_CPU_VAR(pcpu_hot + X86_call_depth);
+ movq %rax, PER_CPU_VAR(__x86_call_depth);
#define RESET_CALL_DEPTH_FROM_CALL \
movb $0xfc, %al; \
shl $56, %rax; \
- movq %rax, PER_CPU_VAR(pcpu_hot + X86_call_depth); \
+ movq %rax, PER_CPU_VAR(__x86_call_depth); \
CALL_THUNKS_DEBUG_INC_CALLS
#define INCREMENT_CALL_DEPTH \
- sarq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth); \
+ sarq $5, PER_CPU_VAR(__x86_call_depth); \
CALL_THUNKS_DEBUG_INC_CALLS
#else
@@ -388,6 +387,8 @@ extern void call_depth_return_thunk(void);
__stringify(INCREMENT_CALL_DEPTH), \
X86_FEATURE_CALL_DEPTH)
+DECLARE_PER_CPU_CACHE_HOT(u64, __x86_call_depth);
+
#ifdef CONFIG_CALL_THUNKS_DEBUG
DECLARE_PER_CPU(u64, __x86_call_count);
DECLARE_PER_CPU(u64, __x86_ret_count);
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index a98020b..6fae88f 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -109,9 +109,6 @@ static void __used common(void)
OFFSET(TSS_sp2, tss_struct, x86_tss.sp2);
OFFSET(X86_top_of_stack, pcpu_hot, top_of_stack);
OFFSET(X86_current_task, pcpu_hot, current_task);
-#ifdef CONFIG_MITIGATION_CALL_DEPTH_TRACKING
- OFFSET(X86_call_depth, pcpu_hot, call_depth);
-#endif
#if IS_ENABLED(CONFIG_CRYPTO_ARIA_AESNI_AVX_X86_64)
/* Offset for fields in aria_ctx */
BLANK();
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c479d3c..ffa291c 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2058,6 +2058,14 @@ DEFINE_PER_CPU_CACHE_HOT(int, __preempt_count) = INIT_PREEMPT_COUNT;
EXPORT_PER_CPU_SYMBOL(__preempt_count);
#ifdef CONFIG_X86_64
+/*
+ * Note: Do not make this dependant on CONFIG_MITIGATION_CALL_DEPTH_TRACKING
+ * so that this space is reserved in the hot cache section even when the
+ * mitigation is disabled.
+ */
+DEFINE_PER_CPU_CACHE_HOT(u64, __x86_call_depth);
+EXPORT_PER_CPU_SYMBOL(__x86_call_depth);
+
static void wrmsrl_cstar(unsigned long val)
{
/*
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 038f49a..a26c43a 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -343,7 +343,7 @@ SYM_FUNC_START(call_depth_return_thunk)
* case.
*/
CALL_THUNKS_DEBUG_INC_RETS
- shlq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth)
+ shlq $5, PER_CPU_VAR(__x86_call_depth)
jz 1f
ANNOTATE_UNRET_SAFE
ret
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