[PATCH] i386: fix task_pt_regs()
)
From: Al Viro <viro@ftp.linux.org.uk>
task_pt_regs() needs the same offset-by-8 to match copy_thread()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 5dd0375..3d7e0c8 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -424,18 +424,7 @@
struct task_struct *tsk;
int err;
- childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
- /*
- * The below -8 is to reserve 8 bytes on top of the ring0 stack.
- * This is necessary to guarantee that the entire "struct pt_regs"
- * is accessable 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 xss/esp fields of the
- * "struct pt_regs" is possible, but they may contain the
- * completely wrong values.
- */
- childregs = (struct pt_regs *) ((unsigned long) childregs - 8);
+ childregs = task_pt_regs(p);
*childregs = *regs;
childregs->eax = 0;
childregs->esp = esp;
@@ -540,12 +529,7 @@
*/
int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
{
- struct pt_regs ptregs;
-
- ptregs = *(struct pt_regs *)
- ((unsigned long)tsk->thread_info +
- /* see comments in copy_thread() about -8 */
- THREAD_SIZE - sizeof(ptregs) - 8);
+ struct pt_regs ptregs = *task_pt_regs(tsk);
ptregs.xcs &= 0xffff;
ptregs.xds &= 0xffff;
ptregs.xes &= 0xffff;
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index a9bf5f2..255adb4 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -875,8 +875,7 @@
/* initialize thread_struct. we really want to avoid destroy
* idle tread
*/
- idle->thread.esp = (unsigned long)(((struct pt_regs *)
- (THREAD_SIZE + (unsigned long) idle->thread_info)) - 1);
+ idle->thread.esp = (unsigned long)task_pt_regs(idle);
init_idle(idle, cpu);
return idle;
}
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index 13ecf66..29ad87e 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -561,10 +561,20 @@
(unsigned long)(&__ptr[THREAD_SIZE_LONGS]); \
})
+/*
+ * The below -8 is to reserve 8 bytes on top of the ring0 stack.
+ * This is necessary to guarantee that the entire "struct pt_regs"
+ * is accessable 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 xss/esp fields of the
+ * "struct pt_regs" is possible, but they may contain the
+ * completely wrong values.
+ */
#define task_pt_regs(task) \
({ \
struct pt_regs *__regs__; \
- __regs__ = (struct pt_regs *)KSTK_TOP((task)->thread_info); \
+ __regs__ = (struct pt_regs *)(KSTK_TOP((task)->thread_info)-8); \
__regs__ - 1; \
})
