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sched/x86: Add 'struct inactive_task_frame' to better document the sleeping task stack frame

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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@gmail.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.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/1471106302-10159-4-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Brian Gerst 2016-08-13 12:38:18 -04:00 committed by Ingo Molnar
parent 163630191e
commit 7b32aeadbc
4 changed files with 11 additions and 4 deletions
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4
arch/x86/include/asm/stacktrace.h
View File

@ -8,6 +8,7 @@
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/ptrace.h> #include <linux/ptrace.h>
#include <asm/switch_to.h>
extern int kstack_depth_to_print; extern int kstack_depth_to_print;
@ -70,8 +71,7 @@ stack_frame(struct task_struct *task, struct pt_regs *regs)
return bp; return bp;
} }
/* bp is the last reg pushed by switch_to */ return ((struct inactive_task_frame *)task->thread.sp)->bp;
return *(unsigned long *)task->thread.sp;
} }
#else #else
static inline unsigned long static inline unsigned long

5
arch/x86/include/asm/switch_to.h
View File

@ -30,6 +30,11 @@ static inline void prepare_switch_to(struct task_struct *prev,
#endif #endif
} }
/* data that is pointed to by thread.sp */
struct inactive_task_frame {
unsigned long bp;
};
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32
#ifdef CONFIG_CC_STACKPROTECTOR #ifdef CONFIG_CC_STACKPROTECTOR

3
arch/x86/kernel/kgdb.c
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@ -50,6 +50,7 @@
#include <asm/apicdef.h> #include <asm/apicdef.h>
#include <asm/apic.h> #include <asm/apic.h>
#include <asm/nmi.h> #include <asm/nmi.h>
#include <asm/switch_to.h>
struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = 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_DX] = 0;
gdb_regs[GDB_SI] = 0; gdb_regs[GDB_SI] = 0;
gdb_regs[GDB_DI] = 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 #ifdef CONFIG_X86_32
gdb_regs[GDB_DS] = __KERNEL_DS; gdb_regs[GDB_DS] = __KERNEL_DS;
gdb_regs[GDB_ES] = __KERNEL_DS; gdb_regs[GDB_ES] = __KERNEL_DS;

3
arch/x86/kernel/process.c
View File

@ -32,6 +32,7 @@
#include <asm/tlbflush.h> #include <asm/tlbflush.h>
#include <asm/mce.h> #include <asm/mce.h>
#include <asm/vm86.h> #include <asm/vm86.h>
#include <asm/switch_to.h>
/* /*
* per-CPU TSS segments. Threads are completely 'soft' on Linux, * 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) if (sp < bottom || sp > top)
return 0; return 0;
fp = READ_ONCE_NOCHECK(*(unsigned long *)sp); fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp);
do { do {
if (fp < bottom || fp > top) if (fp < bottom || fp > top)
return 0; return 0;