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[PATCH] stacktrace build-fix and improvement

To: linux-mips@linux-mips.org
Subject: [PATCH] stacktrace build-fix and improvement
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Thu, 28 Sep 2006 19:15:33 +0900 (JST)
Cc: ralf@linux-mips.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
Fix build error due to stacktrace API change.  Now save_stack_trace()
tries to save all kernel context, including interrupts and exception.
Also some asm code are changed a bit so that we can detect the end of
current context easily.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

 kernel/genex.S      |    8 ++++----
 kernel/stacktrace.c |   52 +++++++++++++++++++++++-----------------------------
 mm/tlbex-fault.S    |    4 ++--
 3 files changed, 29 insertions(+), 35 deletions(-)

diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index 37fda3d..af6ef2f 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -220,8 +220,8 @@ #endif /* CONFIG_MIPS_MT_SMTC */
        CLI
        TRACE_IRQS_OFF
        move    a0, sp
-       jalr    v0
-       j       ret_from_irq
+       PTR_LA  ra, ret_from_irq
+       jr      v0
        END(except_vec_vi_handler)
 
 /*
@@ -349,8 +349,8 @@ #endif
        .set    at
        __BUILD_\verbose \exception
        move    a0, sp
-       jal     do_\handler
-       j       ret_from_exception
+       PTR_LA  ra, ret_from_exception
+       j       do_\handler
        END(handle_\exception)
        .endm
 
diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c
index f851d0c..676e6f6 100644
--- a/arch/mips/kernel/stacktrace.c
+++ b/arch/mips/kernel/stacktrace.c
@@ -13,7 +13,7 @@ #include <asm/stacktrace.h>
  * Save stack-backtrace addresses into a stack_trace buffer:
  */
 static void save_raw_context_stack(struct stack_trace *trace,
-       unsigned int skip, unsigned long reg29)
+       unsigned long reg29)
 {
        unsigned long *sp = (unsigned long *)reg29;
        unsigned long addr;
@@ -21,10 +21,10 @@ static void save_raw_context_stack(struc
        while (!kstack_end(sp)) {
                addr = *sp++;
                if (__kernel_text_address(addr)) {
-                       if (!skip)
-                               trace->entries[trace->nr_entries++] = addr;
+                       if (trace->skip > 0)
+                               trace->skip--;
                        else
-                               skip--;
+                               trace->entries[trace->nr_entries++] = addr;
                        if (trace->nr_entries >= trace->max_entries)
                                break;
                }
@@ -32,37 +32,40 @@ static void save_raw_context_stack(struc
 }
 
 static struct pt_regs * save_context_stack(struct stack_trace *trace,
-       unsigned int skip, struct task_struct *task, struct pt_regs *regs)
+       struct task_struct *task, struct pt_regs *regs)
 {
        unsigned long sp = regs->regs[29];
 #ifdef CONFIG_KALLSYMS
        unsigned long ra = regs->regs[31];
        unsigned long pc = regs->cp0_epc;
+       unsigned long stack_page =
+               (unsigned long)task_stack_page(task);
        extern void ret_from_irq(void);
+       extern void ret_from_exception(void);
 
        if (raw_show_trace || !__kernel_text_address(pc)) {
-               save_raw_context_stack(trace, skip, sp);
+               if (stack_page && sp >= stack_page &&
+                   sp <= stack_page + THREAD_SIZE - 32)
+                       save_raw_context_stack(trace, sp);
                return NULL;
        }
        do {
-               if (!skip)
-                       trace->entries[trace->nr_entries++] = pc;
+               if (trace->skip > 0)
+                       trace->skip--;
                else
-                       skip--;
+                       trace->entries[trace->nr_entries++] = pc;
                if (trace->nr_entries >= trace->max_entries)
                        break;
                /*
                 * If we reached the bottom of interrupt context,
                 * return saved pt_regs.
                 */
-               if (pc == (unsigned long)ret_from_irq) {
-                       unsigned long stack_page =
-                               (unsigned long)task_stack_page(task);
-                       if (!stack_page ||
-                           sp < stack_page ||
-                           sp > stack_page + THREAD_SIZE - 32)
-                               break;
-                       return (struct pt_regs *)sp;
+               if (pc == (unsigned long)ret_from_irq ||
+                   pc == (unsigned long)ret_from_exception) {
+                       if (stack_page && sp >= stack_page &&
+                           sp <= stack_page + THREAD_SIZE - 32)
+                               return (struct pt_regs *)sp;
+                       break;
                }
                pc = unwind_stack(task, &sp, pc, ra);
                ra = 0;
@@ -76,12 +79,8 @@ #endif
 
 /*
  * Save stack-backtrace addresses into a stack_trace buffer.
- * If all_contexts is set, all contexts (hardirq, softirq and process)
- * are saved. If not set then only the current context is saved.
  */
-void save_stack_trace(struct stack_trace *trace,
-                     struct task_struct *task, int all_contexts,
-                     unsigned int skip)
+void save_stack_trace(struct stack_trace *trace, struct task_struct *task)
 {
        struct pt_regs dummyregs;
        struct pt_regs *regs = &dummyregs;
@@ -99,13 +98,8 @@ void save_stack_trace(struct stack_trace
        }
 
        while (1) {
-               regs = save_context_stack(trace, skip, task, regs);
-               if (!all_contexts || !regs ||
-                   trace->nr_entries >= trace->max_entries)
-                       break;
-               trace->entries[trace->nr_entries++] = ULONG_MAX;
-               if (trace->nr_entries >= trace->max_entries)
+               regs = save_context_stack(trace, task, regs);
+               if (!regs || trace->nr_entries >= trace->max_entries)
                        break;
-               skip = 0;
        }
 }
diff --git a/arch/mips/mm/tlbex-fault.S b/arch/mips/mm/tlbex-fault.S
index 9e7f417..e99eaa1 100644
--- a/arch/mips/mm/tlbex-fault.S
+++ b/arch/mips/mm/tlbex-fault.S
@@ -19,8 +19,8 @@ #include <asm/stackframe.h>
        move    a0, sp
        REG_S   a2, PT_BVADDR(sp)
        li      a1, \write
-       jal     do_page_fault
-       j       ret_from_exception
+       PTR_LA  ra, ret_from_exception
+       j       do_page_fault
        END(tlb_do_page_fault_\write)
        .endm
 

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