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authorAndy Lutomirski <luto@kernel.org>2017-11-02 10:59:16 +0300
committerIngo Molnar <mingo@kernel.org>2017-11-02 13:04:48 +0300
commitd375cf1530595e33961a8844192cddab913650e3 (patch)
tree887429bbeeef5048ed511d07a5d8078101129bec /arch/x86/include
parentcd493a6deb8b78eca280d05f7fa73fd69403ae29 (diff)
downloadlinux-d375cf1530595e33961a8844192cddab913650e3.tar.xz
x86/entry/64: Remove thread_struct::sp0
On x86_64, we can easily calculate sp0 when needed instead of storing it in thread_struct. On x86_32, a similar cleanup would be possible, but it would require cleaning up the vm86 code first, and that can wait for a later cleanup series. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/719cd9c66c548c4350d98a90f050aee8b17f8919.1509609304.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include')
-rw-r--r--arch/x86/include/asm/compat.h1
-rw-r--r--arch/x86/include/asm/processor.h28
-rw-r--r--arch/x86/include/asm/switch_to.h6
3 files changed, 16 insertions, 19 deletions
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 5343c19814b3..948b6d8ec46f 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -6,6 +6,7 @@
*/
#include <linux/types.h>
#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
#include <asm/processor.h>
#include <asm/user32.h>
#include <asm/unistd.h>
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index ad59cec14239..ae2ae6d80674 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -430,7 +430,9 @@ typedef struct {
struct thread_struct {
/* Cached TLS descriptors: */
struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES];
+#ifdef CONFIG_X86_32
unsigned long sp0;
+#endif
unsigned long sp;
#ifdef CONFIG_X86_32
unsigned long sysenter_cs;
@@ -797,6 +799,13 @@ static inline void spin_lock_prefetch(const void *x)
#define task_top_of_stack(task) ((unsigned long)(task_pt_regs(task) + 1))
+#define task_pt_regs(task) \
+({ \
+ unsigned long __ptr = (unsigned long)task_stack_page(task); \
+ __ptr += THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; \
+ ((struct pt_regs *)__ptr) - 1; \
+})
+
#ifdef CONFIG_X86_32
/*
* User space process size: 3GB (default).
@@ -816,23 +825,6 @@ static inline void spin_lock_prefetch(const void *x)
.addr_limit = KERNEL_DS, \
}
-/*
- * TOP_OF_KERNEL_STACK_PADDING reserves 8 bytes on top of the ring0 stack.
- * This is necessary to guarantee that the entire "struct pt_regs"
- * is accessible even if the CPU haven't stored the SS/ESP registers
- * on the stack (interrupt gate does not save these registers
- * when switching to the same priv ring).
- * Therefore beware: accessing the ss/esp fields of the
- * "struct pt_regs" is possible, but they may contain the
- * completely wrong values.
- */
-#define task_pt_regs(task) \
-({ \
- unsigned long __ptr = (unsigned long)task_stack_page(task); \
- __ptr += THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; \
- ((struct pt_regs *)__ptr) - 1; \
-})
-
#define KSTK_ESP(task) (task_pt_regs(task)->sp)
#else
@@ -866,11 +858,9 @@ static inline void spin_lock_prefetch(const void *x)
#define STACK_TOP_MAX TASK_SIZE_MAX
#define INIT_THREAD { \
- .sp0 = TOP_OF_INIT_STACK, \
.addr_limit = KERNEL_DS, \
}
-#define task_pt_regs(tsk) ((struct pt_regs *)(tsk)->thread.sp0 - 1)
extern unsigned long KSTK_ESP(struct task_struct *task);
#endif /* CONFIG_X86_64 */
diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index 54e64d909725..010cd6e4eafc 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -1,6 +1,8 @@
#ifndef _ASM_X86_SWITCH_TO_H
#define _ASM_X86_SWITCH_TO_H
+#include <linux/sched/task_stack.h>
+
struct task_struct; /* one of the stranger aspects of C forward declarations */
struct task_struct *__switch_to_asm(struct task_struct *prev,
@@ -87,7 +89,11 @@ static inline void refresh_sysenter_cs(struct thread_struct *thread)
/* This is used when switching tasks or entering/exiting vm86 mode. */
static inline void update_sp0(struct task_struct *task)
{
+#ifdef CONFIG_X86_32
load_sp0(task->thread.sp0);
+#else
+ load_sp0(task_top_of_stack(task));
+#endif
}
#endif /* _ASM_X86_SWITCH_TO_H */