Commit-ID: 7b32aeadbc95d4a41402c1c0da6aa3ab51af4c10
Gitweb: http://git.kernel.org/tip/7b32aeadbc95d4a41402c1c0da6aa3ab51af4c10
Author: Brian Gerst <brgerst@xxxxxxxxx>
AuthorDate: Sat, 13 Aug 2016 12:38:18 -0400
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 24 Aug 2016 12:27:41 +0200
sched/x86: Add 'struct inactive_task_frame' to better document the sleeping task stack frame
Add 'struct inactive_task_frame', which defines the layout of the stack for
a sleeping process. For now, the only defined field is the BP register
(frame pointer).
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/1471106302-10159-4-git-send-email-brgerst@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/stacktrace.h | 4 ++--
arch/x86/include/asm/switch_to.h | 5 +++++
arch/x86/kernel/kgdb.c | 3 ++-
arch/x86/kernel/process.c | 3 ++-
4 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 0944218..7646fb2 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -8,6 +8,7 @@
#include <linux/uaccess.h>
#include <linux/ptrace.h>
+#include <asm/switch_to.h>
extern int kstack_depth_to_print;
@@ -70,8 +71,7 @@ stack_frame(struct task_struct *task, struct pt_regs *regs)
return bp;
}
- /* bp is the last reg pushed by switch_to */
- return *(unsigned long *)task->thread.sp;
+ return ((struct inactive_task_frame *)task->thread.sp)->bp;
}
#else
static inline unsigned long
diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index 14e4b20..ec689c6 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -30,6 +30,11 @@ static inline void prepare_switch_to(struct task_struct *prev,
#endif
}
+/* data that is pointed to by thread.sp */
+struct inactive_task_frame {
+ unsigned long bp;
+};
+
#ifdef CONFIG_X86_32
#ifdef CONFIG_CC_STACKPROTECTOR
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 5e3f294..8e36f24 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -50,6 +50,7 @@
#include <asm/apicdef.h>
#include <asm/apic.h>
#include <asm/nmi.h>
+#include <asm/switch_to.h>
struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
{
@@ -166,7 +167,7 @@ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
gdb_regs[GDB_DX] = 0;
gdb_regs[GDB_SI] = 0;
gdb_regs[GDB_DI] = 0;
- gdb_regs[GDB_BP] = *(unsigned long *)p->thread.sp;
+ gdb_regs[GDB_BP] = ((struct inactive_task_frame *)p->thread.sp)->bp;
#ifdef CONFIG_X86_32
gdb_regs[GDB_DS] = __KERNEL_DS;
gdb_regs[GDB_ES] = __KERNEL_DS;
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 62c0b0e..0115a4a 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -32,6 +32,7 @@
#include <asm/tlbflush.h>
#include <asm/mce.h>
#include <asm/vm86.h>
+#include <asm/switch_to.h>
/*
* per-CPU TSS segments. Threads are completely 'soft' on Linux,
@@ -556,7 +557,7 @@ unsigned long get_wchan(struct task_struct *p)
if (sp < bottom || sp > top)
return 0;
- fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
+ fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp);
do {
if (fp < bottom || fp > top)
return 0;
--
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