Commit-ID: ffcb043ba524d3fbd979a9dac2c9ce8ad352000d
Gitweb: http://git.kernel.org/tip/ffcb043ba524d3fbd979a9dac2c9ce8ad352000d
Author: Brian Gerst <brgerst@xxxxxxxxx>
AuthorDate: Sat, 13 Aug 2016 12:38:21 -0400
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 24 Aug 2016 12:31:51 +0200
sched/x86: Fix thread_saved_pc()
thread_saved_pc() was using a completely bogus method to get the return
address. Since switch_to() was previously inlined, there was no sane way
to know where on the stack the return address was stored. Now with the
frame of a sleeping thread well defined, this can be implemented correctly.
Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
Reviewed-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1471106302-10159-7-git-send-email-brgerst@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/processor.h | 10 ++--------
arch/x86/kernel/process.c | 11 +++++++++++
arch/x86/kernel/process_32.c | 8 --------
3 files changed, 13 insertions(+), 16 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6fee863..b22fb5a 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -721,8 +721,6 @@ static inline void spin_lock_prefetch(const void *x)
.addr_limit = KERNEL_DS, \
}
-extern unsigned long thread_saved_pc(struct task_struct *tsk);
-
/*
* 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"
@@ -773,17 +771,13 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk);
.addr_limit = KERNEL_DS, \
}
-/*
- * Return saved PC of a blocked thread.
- * What is this good for? it will be always the scheduler or ret_from_fork.
- */
-#define thread_saved_pc(t) READ_ONCE_NOCHECK(*(unsigned long *)((t)->thread.sp - 8))
-
#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 */
+extern unsigned long thread_saved_pc(struct task_struct *tsk);
+
extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
unsigned long new_sp);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 0115a4a..c1fa790 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -514,6 +514,17 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
}
/*
+ * Return saved PC of a blocked thread.
+ * What is this good for? it will be always the scheduler or ret_from_fork.
+ */
+unsigned long thread_saved_pc(struct task_struct *tsk)
+{
+ struct inactive_task_frame *frame =
+ (struct inactive_task_frame *) READ_ONCE(tsk->thread.sp);
+ return READ_ONCE_NOCHECK(frame->ret_addr);
+}
+
+/*
* Called from fs/proc with a reference on @p to find the function
* which called into schedule(). This needs to be done carefully
* because the task might wake up and we might look at a stack
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 18714a1..404efdf 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -55,14 +55,6 @@
#include <asm/switch_to.h>
#include <asm/vm86.h>
-/*
- * Return saved PC of a blocked thread.
- */
-unsigned long thread_saved_pc(struct task_struct *tsk)
-{
- return ((unsigned long *)tsk->thread.sp)[3];
-}
-
void __show_regs(struct pt_regs *regs, int all)
{
unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
--
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