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xtensa: clean up access to spilled registers locations

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Define macros SPILL_SLOT* that return a reference to the stack location
of the spill slot for specific register and use them instead of opencoded
address calculations.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov
2015-01-27 01:15:10 +03:00
parent f984409a00
commit 062b1c19b8
4 changed files with 32 additions and 36 deletions
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arch/xtensa/kernel/stacktrace.c
+8 -27
View File
@@ -23,14 +23,6 @@
*/
extern int common_exception_return;
/* A struct that maps to the part of the frame containing the a0 and
* a1 registers.
*/
struct frame_start {
unsigned long a0;
unsigned long a1;
};
void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth,
int (*ufn)(struct stackframe *frame, void *data),
void *data)
@@ -96,26 +88,16 @@ void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth,
/* Start from the a1 register. */
/* a1 = regs->areg[1]; */
while (a0 != 0 && depth--) {
struct frame_start frame_start;
/* Get the location for a1, a0 for the
* previous frame from the current a1.
*/
unsigned long *psp = (unsigned long *)a1;
psp -= 4;
pc = MAKE_PC_FROM_RA(a0, pc);
/* Check if the region is OK to access. */
if (!access_ok(VERIFY_READ, psp, sizeof(frame_start)))
if (!access_ok(VERIFY_READ, &SPILL_SLOT(a1, 0), 8))
return;
/* Copy a1, a0 from user space stack frame. */
if (__copy_from_user_inatomic(&frame_start, psp,
sizeof(frame_start)))
if (__get_user(a0, &SPILL_SLOT(a1, 0)) ||
__get_user(a1, &SPILL_SLOT(a1, 1)))
return;
pc = MAKE_PC_FROM_RA(a0, pc);
a0 = frame_start.a0;
a1 = frame_start.a1;
frame.pc = pc;
frame.sp = a1;
@@ -147,7 +129,6 @@ void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth,
*/
while (a1 > sp_start && a1 < sp_end && depth--) {
struct stackframe frame;
unsigned long *psp = (unsigned long *)a1;
frame.pc = pc;
frame.sp = a1;
@@ -171,8 +152,8 @@ void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth,
sp_start = a1;
pc = MAKE_PC_FROM_RA(a0, pc);
a0 = *(psp - 4);
a1 = *(psp - 3);
a0 = SPILL_SLOT(a1, 0);
a1 = SPILL_SLOT(a1, 1);
}
}
EXPORT_SYMBOL(xtensa_backtrace_kernel);
@@ -196,8 +177,8 @@ void walk_stackframe(unsigned long *sp,
sp = (unsigned long *)a1;
a0 = *(sp - 4);
a1 = *(sp - 3);
a0 = SPILL_SLOT(a1, 0);
a1 = SPILL_SLOT(a1, 1);
if (a1 <= (unsigned long)sp)
break;