/*
* arch/sh/kernel/cpu/sh5/unwind.c
*
* Copyright (C) 2004 Paul Mundt
* Copyright (C) 2004 Richard Curnow
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kallsyms.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/io.h>
static u8 regcache[63];
/*
* Finding the previous stack frame isn't horribly straightforward as it is
* on some other platforms. In the sh64 case, we don't have "linked" stack
* frames, so we need to do a bit of work to determine the previous frame,
* and in turn, the previous r14/r18 pair.
*
* There are generally a few cases which determine where we can find out
* the r14/r18 values. In the general case, this can be determined by poking
* around the prologue of the symbol PC is in (note that we absolutely must
* have frame pointer support as well as the kernel symbol table mapped,
* otherwise we can't even get this far).
*
* In other cases, such as the interrupt/exception path, we can poke around
* the sp/fp.
*
* Notably, this entire approach is somewhat error prone, and in the event
* that the previous frame cannot be determined, that's all we can do.
* Either way, this still leaves us with a more correct backtrace then what
* we would be able to come up with by walking the stack (which is garbage
* for anything beyond the first frame).
* -- PFM.
*/
static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
unsigned long *pprev_fp, unsigned long *pprev_pc,
struct pt_regs *regs)
{
const char *sym;
char namebuf[128];
unsigned long offset;
unsigned long prologue = 0;
unsigned long fp_displacement = 0;
unsigned long fp_prev = 0;
unsigned long offset_r14 = 0, offset_r18 = 0;
int i, found_prologue_end = 0;
sym = kallsyms_lookup(pc, NULL, &offset, NULL, namebuf);
if (!sym)
return -EINVAL;
prologue = pc - offset;
if (!prologue)
return -EINVAL;
/* Validate fp, to avoid risk of dereferencing a bad pointer later.
Assume 128Mb since that's the amount of RAM on a Cayman. Modify
when there is an SH-5 board with more. */
if ((fp < (unsigned long) phys_to_virt(__MEMORY_START)) ||
(fp >= (unsigned long)(phys_to_virt(__MEMORY_START)) + 128*1024*1024) ||
((fp & 7) != 0)) {
return -EINVAL;
}
/*
* Depth to walk, depth is completely arbitrary.
*/
for (i = 0; i < 100; i++, prologue += sizeof(unsigned long)) {
unsigned long op;
u8 major, minor;
u8 src, dest, disp;
op = *(unsigned long *)prologue;
major = (op >> 26) & 0x3f;
src = (op >> 20) & 0x3f;
minor = (op >> 16) & 0xf;
disp = (op >> 10) & 0x3f;
dest = (op >> 4) & 0x3f;
/*
* Stack frame creation happens in a number of ways.. in the
* general case when the stack frame is less than 511 bytes,
* it's generally created by an addi or addi.l:
*
* addi/addi.l r15, -FRAME_SIZE, r15
*
* in the event that the frame size is bigger than this, it's
* typically created using a movi/sub pair as follows:
*
* movi FRAME_SIZE, rX
* sub r15, rX, r15
*/
switch (major) {
case (0x00 >> 2):
switch (minor) {
case 0x8: /* add.l */
case 0x9: /* add */
/* Look for r15, r63, r14 */
if (src == 15 && disp == 63 && dest == 14)
found_prologue_end = 1;
break;
case 0xa: /* sub.l */
case 0xb: /* sub */
if (src != 15 || dest != 15)
continue;
fp_displacement -= regcache[disp];
fp_prev = fp - fp_displacement;
break;
}
break;
case (0xa8 >> 2): /* st.l */
if (src != 15)
continue;
switch (dest) {
case 14:
if (offset_r14 || fp_displacement == 0)
continue;
offset_r14 = (u64)(((((s64)op >> 10) & 0x3ff) << 54) >> 54);
offset_r14 *= sizeof(unsigned long);
offset_r14 += fp_displacement;
break;
case 18:
if (offset_r18 || fp_displacement == 0)
continue;
offset_r18 = (u64)(((((s64)op >> 10) & 0x3ff) << 54) >> 54);
offset_r18 *= sizeof(unsigned long);
offset_r18 += fp_displacement;
break;
}
break;
case (0xcc >> 2): /* movi */
if (dest >= 63) {
printk(KERN_NOTICE "%s: Invalid dest reg %d "
"specified in movi handler. Failed "
"opcode was 0x%lx: ", __func__,
dest, op);
continue;
}
/* Sign extend */
regcache[dest] =
((((s64)(u64)op >> 10) & 0xffff) << 54) >> 54;
break;
case (0xd0 >> 2): /* addi */
case (0xd4 >> 2): /* addi.l */
/* Look for r15, -FRAME_SIZE, r15 */
if (src != 15 || dest != 15)
continue;
/* Sign extended frame size.. */
fp_displacement +=
(u64)(((((s64)op >> 10) & 0x3ff) << 54) >> 54);
fp_prev = fp - fp_displacement;
break;
}
if (found_prologue_end && offset_r14 && (offset_r18 || *pprev_pc) && fp_prev)
break;
}
if (offset_r14 == 0 || fp_prev == 0) {
if (!offset_r14)
pr_debug("Unable to find r14 offset\n");
if (!fp_prev)
pr_debug("Unable to find previous fp\n");
return -EINVAL;
}
/* For innermost leaf function, there might not be a offset_r18 */
if (!*pprev_pc && (offset_r18 == 0))
return -EINVAL;
*pprev_fp = *(unsigned long *)(fp_prev + offset_r14);
if (offset_r18)
*pprev_pc = *(unsigned long *)(fp_prev + offset_r18);
*pprev_pc &= ~1;
return 0;
}
/* Don't put this on the stack since we'll want to call sh64_unwind
* when we're close to underflowing the stack anyway. */
static struct pt_regs here_regs;
extern const char syscall_ret;
extern const char ret_from_syscall;
extern const char ret_from_exception;
extern const char ret_from_irq;
static void sh64_unwind_inner(struct pt_regs *regs);
static void unwind_nested (unsigned long pc, unsigned long fp)
{
if ((fp >= __MEMORY_START) &&
((fp & 7) == 0)) {
sh64_unwind_inner((struct pt_regs *) fp);
}
}
static void sh64_unwind_inner(struct pt_regs *regs)
{
unsigned long pc, fp;
int ofs = 0;
int first_pass;
pc = regs->pc & ~1;
fp = regs->regs[14];
first_pass = 1;
for (;;) {
int cond;
unsigned long next_fp, next_pc;
if (pc == ((unsigned long) &syscall_ret & ~1)) {
printk("SYSCALL\n");
unwind_nested(pc,fp);
return;
}
if (pc == ((unsigned long) &ret_from_syscall & ~1)) {
printk("SYSCALL (PREEMPTED)\n");
unwind_nested(pc,fp);
return;
}
/* In this case, the PC is discovered by lookup_prev_stack_frame but
it has 4 taken off it to look like the 'caller' */
if (pc == ((unsigned long) &ret_from_exception & ~1)) {
printk("EXCEPTION\n");
unwind_nested(pc,fp);
return;
}
if (pc == ((unsigned long) &ret_from_irq & ~1)) {
printk("IRQ\n");
unwind_nested(pc,fp);
return;
}
cond = ((pc >= __MEMORY_START) && (fp >= __MEMORY_START) &&
((pc & 3) == 0) && ((fp & 7) == 0));
pc -= ofs;
printk("[<%08lx>] ", pc);
print_symbol("%s\n", pc);
if (first_pass) {
/* If the innermost frame is a leaf function, it's
* possible that r18 is never saved out to the stack.
*/
next_pc = regs->regs[18];
} else {
next_pc = 0;
}
if (lookup_prev_stack_frame(fp, pc, &next_fp, &next_pc, regs) == 0) {
ofs = sizeof(unsigned long);
pc = next_pc & ~1;
fp = next_fp;
} else {
printk("Unable to lookup previous stack frame\n");
break;
}
first_pass = 0;
}
printk("\n");
}
void sh64_unwind(struct pt_regs *regs)
{
if (!regs) {
/*
* Fetch current regs if we have no other saved state to back
* trace from.
*/
regs = &here_regs;
__asm__ __volatile__ ("ori r14, 0, %0" : "=r" (regs->regs[14]));
__asm__ __volatile__ ("ori r15, 0, %0" : "=r" (regs->regs[15]));
__asm__ __volatile__ ("ori r18, 0, %0" : "=r" (regs->regs[18]));
__asm__ __volatile__ ("gettr tr0, %0" : "=r" (regs->tregs[0]));
__asm__ __volatile__ ("gettr tr1, %0" : "=r" (regs->tregs[1]));
__asm__ __volatile__ ("gettr tr2, %0" : "=r" (regs->tregs[2]));
__asm__ __volatile__ ("gettr tr3, %0" : "=r" (regs->tregs[3]));
__asm__ __volatile__ ("gettr tr4, %0" : "=r" (regs->tregs[4]));
__asm__ __volatile__ ("gettr tr5, %0" : "=r" (regs->tregs[5]));
__asm__ __volatile__ ("gettr tr6, %0" : "=r" (regs->tregs[6]));
__asm__ __volatile__ ("gettr tr7, %0" : "=r" (regs->tregs[7]));
__asm__ __volatile__ (
"pta 0f, tr0\n\t"
"blink tr0, %0\n\t"
"0: nop"
: "=r" (regs->pc)
);
}
printk("\nCall Trace:\n");
sh64_unwind_inner(regs);
}
