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[PATCH] i386: fix task_pt_regs()

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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>
This commit is contained in:
akpm@osdl.org 2006-01-12 01:05:41 -08:00 committed by Linus Torvalds
parent 06b425d80f
commit 07b047fc24
3 changed files with 14 additions and 21 deletions
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20
arch/i386/kernel/process.c
View File

@ -424,18 +424,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
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 @@ EXPORT_SYMBOL(dump_thread);
*/
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;

3
arch/i386/kernel/smpboot.c
View File

@ -875,8 +875,7 @@ static inline struct task_struct * alloc_idle_task(int cpu)
/* 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;
}

12
include/asm-i386/processor.h
View File

@ -561,10 +561,20 @@ unsigned long get_wchan(struct task_struct *p);
(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; \
})