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Message-ID: <20250222190623.262689-6-brgerst@gmail.com>
Date: Sat, 22 Feb 2025 14:06:17 -0500
From: Brian Gerst <brgerst@...il.com>
To: linux-kernel@...r.kernel.org,
x86@...nel.org
Cc: Ingo Molnar <mingo@...nel.org>,
"H . Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
Ard Biesheuvel <ardb@...nel.org>,
Uros Bizjak <ubizjak@...il.com>,
Brian Gerst <brgerst@...il.com>
Subject: [RFC PATCH 05/11] x86/percpu: Move top_of_stack to percpu hot section
No functional change.
Signed-off-by: Brian Gerst <brgerst@...il.com>
---
arch/x86/entry/entry_32.S | 4 ++--
arch/x86/entry/entry_64.S | 6 +++---
arch/x86/entry/entry_64_compat.S | 4 ++--
arch/x86/include/asm/current.h | 1 -
arch/x86/include/asm/percpu.h | 2 +-
arch/x86/include/asm/processor.h | 8 ++++++--
arch/x86/kernel/asm-offsets.c | 1 -
arch/x86/kernel/cpu/common.c | 3 ++-
arch/x86/kernel/process_32.c | 4 ++--
arch/x86/kernel/process_64.c | 2 +-
arch/x86/kernel/smpboot.c | 2 +-
arch/x86/kernel/vmlinux.lds.S | 1 +
12 files changed, 21 insertions(+), 17 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 20be5758c2d2..92c0b4a94e0a 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1153,7 +1153,7 @@ SYM_CODE_START(asm_exc_nmi)
* is using the thread stack right now, so it's safe for us to use it.
*/
movl %esp, %ebx
- movl PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %esp
+ movl PER_CPU_VAR(cpu_current_top_of_stack), %esp
call exc_nmi
movl %ebx, %esp
@@ -1217,7 +1217,7 @@ SYM_CODE_START(rewind_stack_and_make_dead)
/* Prevent any naive code from trying to unwind to our caller. */
xorl %ebp, %ebp
- movl PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %esi
+ movl PER_CPU_VAR(cpu_current_top_of_stack), %esi
leal -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%esi), %esp
call make_task_dead
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 33a955aa01d8..9baf32a7a118 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -92,7 +92,7 @@ SYM_CODE_START(entry_SYSCALL_64)
/* tss.sp2 is scratch space. */
movq %rsp, PER_CPU_VAR(cpu_tss_rw + TSS_sp2)
SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp
- movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp
+ movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
SYM_INNER_LABEL(entry_SYSCALL_64_safe_stack, SYM_L_GLOBAL)
ANNOTATE_NOENDBR
@@ -1166,7 +1166,7 @@ SYM_CODE_START(asm_exc_nmi)
FENCE_SWAPGS_USER_ENTRY
SWITCH_TO_KERNEL_CR3 scratch_reg=%rdx
movq %rsp, %rdx
- movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp
+ movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
UNWIND_HINT_IRET_REGS base=%rdx offset=8
pushq 5*8(%rdx) /* pt_regs->ss */
pushq 4*8(%rdx) /* pt_regs->rsp */
@@ -1484,7 +1484,7 @@ SYM_CODE_START_NOALIGN(rewind_stack_and_make_dead)
/* Prevent any naive code from trying to unwind to our caller. */
xorl %ebp, %ebp
- movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rax
+ movq PER_CPU_VAR(cpu_current_top_of_stack), %rax
leaq -PTREGS_SIZE(%rax), %rsp
UNWIND_HINT_REGS
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index ed0a5f2dc129..a45e1125fc6c 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -57,7 +57,7 @@ SYM_CODE_START(entry_SYSENTER_compat)
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
popq %rax
- movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp
+ movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
/* Construct struct pt_regs on stack */
pushq $__USER_DS /* pt_regs->ss */
@@ -193,7 +193,7 @@ SYM_CODE_START(entry_SYSCALL_compat)
SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp
/* Switch to the kernel stack */
- movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp
+ movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
SYM_INNER_LABEL(entry_SYSCALL_compat_safe_stack, SYM_L_GLOBAL)
ANNOTATE_NOENDBR
diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h
index fbc7eb92adb2..8adbe0e3c5e7 100644
--- a/arch/x86/include/asm/current.h
+++ b/arch/x86/include/asm/current.h
@@ -16,7 +16,6 @@ struct pcpu_hot {
union {
struct {
struct task_struct *current_task;
- unsigned long top_of_stack;
void *hardirq_stack_ptr;
u16 softirq_pending;
#ifdef CONFIG_X86_64
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 1a76eb87c5d8..cc19bd785f0e 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -560,7 +560,7 @@ do { \
* it is accessed while this_cpu_read_stable() allows the value to be cached.
* this_cpu_read_stable() is more efficient and can be used if its value
* is guaranteed to be valid across CPUs. The current users include
- * pcpu_hot.current_task and pcpu_hot.top_of_stack, both of which are
+ * pcpu_hot.current_task and cpu_current_top_of_stack, both of which are
* actually per-thread variables implemented as per-CPU variables and
* thus stable for the duration of the respective task.
*/
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index b3d153730f63..1505cb1d09a8 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -420,6 +420,10 @@ struct irq_stack {
char stack[IRQ_STACK_SIZE];
} __aligned(IRQ_STACK_SIZE);
+DECLARE_PER_CPU_HOT(unsigned long, cpu_current_top_of_stack);
+/* const-qualified alias provided by the linker. */
+DECLARE_PER_CPU_HOT(const unsigned long, const_cpu_current_top_of_stack);
+
#ifdef CONFIG_X86_64
static inline unsigned long cpu_kernelmode_gs_base(int cpu)
{
@@ -545,9 +549,9 @@ static __always_inline unsigned long current_top_of_stack(void)
* entry trampoline.
*/
if (IS_ENABLED(CONFIG_USE_X86_SEG_SUPPORT))
- return this_cpu_read_const(const_pcpu_hot.top_of_stack);
+ return this_cpu_read_const(const_cpu_current_top_of_stack);
- return this_cpu_read_stable(pcpu_hot.top_of_stack);
+ return this_cpu_read_stable(cpu_current_top_of_stack);
}
static __always_inline bool on_thread_stack(void)
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 6fae88f8ae1e..54ace808defd 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -107,7 +107,6 @@ static void __used common(void)
OFFSET(TSS_sp0, tss_struct, x86_tss.sp0);
OFFSET(TSS_sp1, tss_struct, x86_tss.sp1);
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);
#if IS_ENABLED(CONFIG_CRYPTO_ARIA_AESNI_AVX_X86_64)
/* Offset for fields in aria_ctx */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 519e2ec2027d..25a5806e15aa 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2016,7 +2016,6 @@ __setup("clearcpuid=", setup_clearcpuid);
DEFINE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot) = {
.current_task = &init_task,
- .top_of_stack = TOP_OF_INIT_STACK,
};
EXPORT_PER_CPU_SYMBOL(pcpu_hot);
EXPORT_PER_CPU_SYMBOL(const_pcpu_hot);
@@ -2024,6 +2023,8 @@ EXPORT_PER_CPU_SYMBOL(const_pcpu_hot);
DEFINE_PER_CPU_HOT(int, __preempt_count) = INIT_PREEMPT_COUNT;
EXPORT_PER_CPU_SYMBOL(__preempt_count);
+DEFINE_PER_CPU_HOT(unsigned long, cpu_current_top_of_stack) = TOP_OF_INIT_STACK;
+
#ifdef CONFIG_X86_64
static void wrmsrl_cstar(unsigned long val)
{
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 0917c7f25720..3afb2428bedb 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -190,13 +190,13 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
arch_end_context_switch(next_p);
/*
- * Reload esp0 and pcpu_hot.top_of_stack. This changes
+ * Reload esp0 and cpu_current_top_of_stack. This changes
* current_thread_info(). Refresh the SYSENTER configuration in
* case prev or next is vm86.
*/
update_task_stack(next_p);
refresh_sysenter_cs(next);
- this_cpu_write(pcpu_hot.top_of_stack,
+ this_cpu_write(cpu_current_top_of_stack,
(unsigned long)task_stack_page(next_p) +
THREAD_SIZE);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 226472332a70..4252b11718f2 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -669,7 +669,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
* Switch the PDA and FPU contexts.
*/
raw_cpu_write(pcpu_hot.current_task, next_p);
- raw_cpu_write(pcpu_hot.top_of_stack, task_top_of_stack(next_p));
+ raw_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p));
switch_fpu_finish(next_p);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index c10850ae6f09..15e054f4cbf6 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -851,7 +851,7 @@ int common_cpu_up(unsigned int cpu, struct task_struct *idle)
#ifdef CONFIG_X86_32
/* Stack for startup_32 can be just as for start_secondary onwards */
- per_cpu(pcpu_hot.top_of_stack, cpu) = task_top_of_stack(idle);
+ per_cpu(cpu_current_top_of_stack, cpu) = task_top_of_stack(idle);
#endif
return 0;
}
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 049485513f3c..ee019c1ea859 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -44,6 +44,7 @@ ENTRY(phys_startup_64)
jiffies = jiffies_64;
const_pcpu_hot = pcpu_hot;
+const_cpu_current_top_of_stack = cpu_current_top_of_stack;
#if defined(CONFIG_X86_64)
/*
--
2.48.1
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