The patch titled
ptrace: Fix EFL_OFFSET value according to i386 pda changes
has been removed from the -mm tree. Its filename was
ptrace-fix-efl_offset-value-according-to-i386-pda-changes.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: ptrace: Fix EFL_OFFSET value according to i386 pda changes
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
The PDA patches introduced a bug in ptrace: it reads eflags from the wrong
place on the target's stack, but writes it back to the correct place. The
result is a corrupted eflags, which is most visible when it turns interrupts
off unexpectedly.
This patch fixes this by making the ptrace code a little less fragile. It
changes [gs]et_stack_long to take a straightforward byte offset into struct
pt_regs, rather than requiring all callers to do a sizeof(struct pt_regs)
offset adjustment. This means that the eflag's offset (EFL_OFFSET) on the
target stack can be simply computed with offsetof().
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Frederik Deweerdt <deweerdt@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/kernel/ptrace.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff -puN arch/i386/kernel/ptrace.c~ptrace-fix-efl_offset-value-according-to-i386-pda-changes arch/i386/kernel/ptrace.c
--- a/arch/i386/kernel/ptrace.c~ptrace-fix-efl_offset-value-according-to-i386-pda-changes
+++ a/arch/i386/kernel/ptrace.c
@@ -45,7 +45,7 @@
/*
* Offset of eflags on child stack..
*/
-#define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs))
+#define EFL_OFFSET offsetof(struct pt_regs, eflags)
static inline struct pt_regs *get_child_regs(struct task_struct *task)
{
@@ -54,24 +54,24 @@ static inline struct pt_regs *get_child_
}
/*
- * this routine will get a word off of the processes privileged stack.
- * the offset is how far from the base addr as stored in the TSS.
- * this routine assumes that all the privileged stacks are in our
+ * This routine will get a word off of the processes privileged stack.
+ * the offset is bytes into the pt_regs structure on the stack.
+ * This routine assumes that all the privileged stacks are in our
* data space.
*/
static inline int get_stack_long(struct task_struct *task, int offset)
{
unsigned char *stack;
- stack = (unsigned char *)task->thread.esp0;
+ stack = (unsigned char *)task->thread.esp0 - sizeof(struct pt_regs);
stack += offset;
return (*((int *)stack));
}
/*
- * this routine will put a word on the processes privileged stack.
- * the offset is how far from the base addr as stored in the TSS.
- * this routine assumes that all the privileged stacks are in our
+ * This routine will put a word on the processes privileged stack.
+ * the offset is bytes into the pt_regs structure on the stack.
+ * This routine assumes that all the privileged stacks are in our
* data space.
*/
static inline int put_stack_long(struct task_struct *task, int offset,
@@ -79,7 +79,7 @@ static inline int put_stack_long(struct
{
unsigned char * stack;
- stack = (unsigned char *) task->thread.esp0;
+ stack = (unsigned char *)task->thread.esp0 - sizeof(struct pt_regs);
stack += offset;
*(unsigned long *) stack = data;
return 0;
@@ -114,7 +114,7 @@ static int putreg(struct task_struct *ch
}
if (regno > ES*4)
regno -= 1*4;
- put_stack_long(child, regno - sizeof(struct pt_regs), value);
+ put_stack_long(child, regno, value);
return 0;
}
@@ -137,7 +137,6 @@ static unsigned long getreg(struct task_
default:
if (regno > ES*4)
regno -= 1*4;
- regno = regno - sizeof(struct pt_regs);
retval &= get_stack_long(child, regno);
}
return retval;
_
Patches currently in -mm which might be from jeremy@xxxxxxxx are
origin.patch
convert-i386-pda-code-to-use-%fs.patch
convert-i386-pda-code-to-use-%fs-ptrace-make-putgetreg-work-again-for-gs-and-fs.patch
gtod-uninline-jiffiesh.patch
-
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