summaryrefslogtreecommitdiffstats
path: root/arch/sh64/kernel/unwind.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/sh64/kernel/unwind.c')
-rw-r--r--arch/sh64/kernel/unwind.c326
1 files changed, 326 insertions, 0 deletions
diff --git a/arch/sh64/kernel/unwind.c b/arch/sh64/kernel/unwind.c
new file mode 100644
index 0000000..f934f97
--- /dev/null
+++ b/arch/sh64/kernel/unwind.c
@@ -0,0 +1,326 @@
+/*
+ * arch/sh64/kernel/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 *modname, namebuf[128];
+ unsigned long offset, size;
+ 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, &size, &offset, &modname, 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: ", __FUNCTION__,
+ 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);
+}
+
OpenPOWER on IntegriCloud