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Groups > linux.kernel > #1461654
| From | Brian Gerst <brgerst@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v3 6/7] x86: Fix thread_saved_pc() |
| Date | 2016-08-13 18:50 +0200 |
| Message-ID | <s5Kid-3N8-9@gated-at.bofh.it> (permalink) |
| References | <s5K8x-3J2-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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@gmail.com>
---
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;
--
2.5.5
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[PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
[PATCH v3 1/7] x86-32, kgdb: Don't use thread.ip in sleeping_thread_to_gdb_regs() Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
[tip:x86/asm] sched/x86/32, kgdb: Don't use thread.ip in sleeping_thread_to_gdb_regs() tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:50 +0200
[PATCH v3 7/7] Revert "sched: Mark __schedule() stack frame as non-standard" Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
[tip:x86/asm] sched: Remove __schedule() non-standard frame annotation tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:50 +0200
[PATCH v3 2/7] x86-64, kgdb: clear GDB_PS on 64-bit Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
[tip:x86/asm] sched/x86/64, kgdb: Clear GDB_PS on 64-bit tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:50 +0200
[PATCH v3 3/7] x86: Add struct inactive_task_frame Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
[tip:x86/asm] sched/x86: Add 'struct inactive_task_frame' to better document the sleeping task stack frame tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:20 +0200
[PATCH v3 4/7] x86: Rewrite switch_to() code Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:50 +0200
[tip:x86/asm] sched/x86: Rewrite the switch_to() code tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:20 +0200
[PATCH v3 6/7] x86: Fix thread_saved_pc() Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:50 +0200
[tip:x86/asm] sched/x86: Fix thread_saved_pc() tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:20 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-13 19:20 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Ingo Molnar <mingo@kernel.org> - 2016-08-14 10:30 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Andy Lutomirski <luto@amacapital.net> - 2016-08-14 13:20 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Herbert Xu <herbert@gondor.apana.org.au> - 2016-08-17 07:20 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-14 16:20 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Ingo Molnar <mingo@kernel.org> - 2016-08-15 07:20 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-15 13:50 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Andy Lutomirski <luto@amacapital.net> - 2016-08-17 23:30 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-14 12:30 +0200
Re: [PATCH v3 0/7] x86: Rewrite switch_to() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-08-17 23:30 +0200
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