----- Original Message -----
> Rabin,
>
> New it works fine! Thanks!
>
> Sagar
Rabin,
Do you want me to apply this patch as-is, or are you planning to
repost it?
Thanks,
Dave
>
> On Wed, Oct 19, 2016 at 3:36 PM, Rabin Vincent <rabin@xxxxxx> wrote:
> > On Tue, Oct 18, 2016 at 04:10:51PM -0700, Sagar Borikar wrote:
> >> I tried these patches but still don't get correct bt output.
> >
> > I think I see the problem now. Your EPC is 0 so we hit the if
> > (!IS_KVADDR(current.pc)) condition on the first iteration of the
> > backtrace loop and exit without trying futher.
> >
> > Could you please try the following patch? Please include a log with
> > debugging enabled ("set debug 8") if it still doesn't work. Thanks.
> >
> > 8<------------------
> > >From 4ae6ab8d181deea53ece847007d27d228166370d Mon Sep 17 00:00:00 2001
> > From: Rabin Vincent <rabinv@xxxxxxxx>
> > Date: Thu, 20 Oct 2016 00:19:33 +0200
> > Subject: [PATCH] mips: allow one invalid PC at start or after exception
> >
> > Before:
> >
> > PID: 2810 TASK: 835e41a8 CPU: 1 COMMAND: "sh"
> > #0 [8315bb00] crash_kexec at 800b26a4
> > #1 [8315bbe0] panic at 800dc0fc
> > #2 [8315bc20] die at 8001fa74
> > #3 [8315bc50] __do_page_fault at 8002de74
> > #4 [8315bd28] ret_from_irq at 80019624
> > $ 0 : 00000000 00000001 80690000 00000000
> > $ 4 : 00000063 812972dc 81297db8 000000c2
> > $ 8 : 00004b38 00000001 80680000 80620000
> > $12 : 00000104 00000002 00000000 00000000
> > $16 : 80622530 80620000 00000063 80620000
> > $20 : 80622470 00000001 00000000 00b9f322
> > $24 : 00000003 00000000 00440000 800dca80
> > $28 : 8315a000 8315bde0 00000000 80313b30
> > Hi : 00000046
> > Lo : 0f5c2a0e
> > epc : 00000000
> > ra : 80313b30 __handle_sysrq+0x144
> > Status: 1100fc03
> > Cause : 10800008
> > BadVA : 00000000
> >
> > After:
> >
> > crash> bt
> > PID: 2810 TASK: 835e41a8 CPU: 1 COMMAND: "sh"
> > #0 [8315bb00] crash_kexec at 800b26a4
> > #1 [8315bbe0] panic at 800dc0fc
> > #2 [8315bc20] die at 8001fa74
> > #3 [8315bc50] __do_page_fault at 8002de74
> > #4 [8315bd28] ret_from_irq at 80019624
> > $ 0 : 00000000 00000001 80690000 00000000
> > $ 4 : 00000063 812972dc 81297db8 000000c2
> > $ 8 : 00004b38 00000001 80680000 80620000
> > $12 : 00000104 00000002 00000000 00000000
> > $16 : 80622530 80620000 00000063 80620000
> > $20 : 80622470 00000001 00000000 00b9f322
> > $24 : 00000003 00000000 00440000 800dca80
> > $28 : 8315a000 8315bde0 00000000 80313b30
> > Hi : 00000046
> > Lo : 0f5c2a0e
> > epc : 00000000
> > ra : 80313b30 __handle_sysrq+0x144
> > Status: 1100fc03
> > Cause : 10800008
> > BadVA : 00000000
> > #5 [8315bde0] (invalid) at 0
> > #6 [8315bde0] __handle_sysrq at 80313b30
> > #7 [8315be18] write_sysrq_trigger at 80313c24
> > #8 [8315be38] proc_reg_write at 80178074
> > #9 [8315be58] __vfs_write at 8011ea78
> > #10 [8315bec0] vfs_write at 8011fe7c
> > #11 [8315bef0] sys_write at 801201e8
> > #12 [8315bf28] syscall_common at 800275c8
> > ---
> > mips.c | 35 +++++++++++++++++++++++++----------
> > 1 file changed, 25 insertions(+), 10 deletions(-)
> >
> > diff --git a/mips.c b/mips.c
> > index 6cd8d1f..1bb4d27 100644
> > --- a/mips.c
> > +++ b/mips.c
> > @@ -413,7 +413,7 @@ mips_dump_backtrace_entry(struct bt_info *bt, struct
> > syment *sym,
> > struct mips_unwind_frame *current,
> > struct mips_unwind_frame *previous, int level)
> > {
> > - const char *name = sym->name;
> > + const char *name = sym ? sym->name : "(invalid)";
> > struct load_module *lm;
> > char *name_plus_offset;
> > char buf[BUFSIZE];
> > @@ -447,7 +447,7 @@ mips_dump_backtrace_entry(struct bt_info *bt, struct
> > syment *sym,
> > fprintf(fp, " %s\n", buf);
> > }
> >
> > - if (mips_is_exception_entry(sym)) {
> > + if (sym && mips_is_exception_entry(sym)) {
> > char pt_regs[SIZE(pt_regs)];
> >
> > GET_STACK_DATA(current->sp, &pt_regs, SIZE(pt_regs));
> > @@ -533,6 +533,7 @@ mips_back_trace_cmd(struct bt_info *bt)
> > {
> > struct mips_unwind_frame current, previous;
> > int level = 0;
> > + int invalid_ok = 1;
> >
> > if (bt->flags & BT_REGS_NOT_FOUND)
> > return;
> > @@ -549,22 +550,24 @@ mips_back_trace_cmd(struct bt_info *bt)
> > }
> >
> > while (INSTACK(current.sp, bt)) {
> > - struct syment *symbol;
> > + struct syment *symbol = NULL;
> > ulong offset;
> >
> > if (CRASHDEBUG(8))
> > fprintf(fp, "level %d pc %#lx ra %#lx sp %lx\n",
> > level, current.pc, current.ra, current.sp);
> >
> > - if (!IS_KVADDR(current.pc))
> > + if (!IS_KVADDR(current.pc) && !invalid_ok)
> > return;
> >
> > symbol = value_search(current.pc, &offset);
> > - if (!symbol) {
> > + if (!symbol && !invalid_ok) {
> > error(FATAL, "PC is unknown symbol (%lx)",
> > current.pc);
> > return;
> > }
> >
> > + invalid_ok = 0;
> > +
> > /*
> > * If we get an address which points to the start of a
> > * function, then it could one of the following:
> > @@ -586,7 +589,7 @@ mips_back_trace_cmd(struct bt_info *bt)
> > * * ret_from_fork
> > * * ret_from_kernel_thread
> > */
> > - if (!current.ra && !offset && !STRNEQ(symbol->name,
> > "ret_from")) {
> > + if (!current.ra && !offset && symbol &&
> > !STRNEQ(symbol->name, "ret_from")) {
> > if (CRASHDEBUG(8))
> > fprintf(fp, "zero offset at %s, try
> > previous symbol\n",
> > symbol->name);
> > @@ -598,7 +601,7 @@ mips_back_trace_cmd(struct bt_info *bt)
> > }
> > }
> >
> > - if (mips_is_exception_entry(symbol)) {
> > + if (symbol && mips_is_exception_entry(symbol)) {
> > struct mips_pt_regs_main *mains;
> > struct mips_pt_regs_cp0 *cp0;
> > char pt_regs[SIZE(pt_regs)];
> > @@ -617,18 +620,30 @@ mips_back_trace_cmd(struct bt_info *bt)
> > if (CRASHDEBUG(8))
> > fprintf(fp, "exception pc %#lx ra %#lx sp
> > %lx\n",
> > previous.pc, previous.ra,
> > previous.sp);
> > - } else {
> > +
> > + /* The PC causing the exception may have been
> > invalid */
> > + invalid_ok = 1;
> > + } else if (symbol) {
> > mips_analyze_function(symbol->value, offset,
> > ¤t, &previous);
> > + } else {
> > + /*
> > + * The current PC is invalid. Assume that the code
> > + * jumped through a invalid pointer and that the SP
> > has
> > + * not been adjusted.
> > + */
> > + previous.sp = current.sp;
> > }
> >
> > mips_dump_backtrace_entry(bt, symbol, ¤t, &previous,
> > level++);
> > - if (!current.ra)
> > - break;
> >
> > current.pc = current.ra;
> > current.sp = previous.sp;
> > current.ra = previous.ra;
> >
> > + if (CRASHDEBUG(8))
> > + fprintf(fp, "next %d pc %#lx ra %#lx sp %lx\n",
> > + level, current.pc, current.ra, current.sp);
> > +
> > previous.sp = previous.pc = previous.ra = 0;
> > }
> > }
> > --
> > 2.1.4
> >
> > --
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>
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