[PATCH] tile: improve illegal translation interrupt handling

From: Chris Metcalf
Date: Wed Aug 07 2013 - 16:41:01 EST


First, don't re-enable interrupts blindly in the Linux trap handler.
We already handle page faults this way; synchronous interrupts like
ILL_TRANS will fire even when interrupts are disabled, and we don't
want to re-enable interrupts in that case.

For ILL_TRANS, we now pass the ILL_VA_PC reason into the trap handler
so we can report it properly; this is the address that caused the
illegal translation trap. We print the address as part of the
pr_alert() message now if it's coming from the kernel.

Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
---
arch/tile/kernel/intvec_64.S | 2 +-
arch/tile/kernel/traps.c | 25 +++++++++++++++----------
2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/arch/tile/kernel/intvec_64.S b/arch/tile/kernel/intvec_64.S
index 8e7d6b8..3c63fbd 100644
--- a/arch/tile/kernel/intvec_64.S
+++ b/arch/tile/kernel/intvec_64.S
@@ -485,7 +485,7 @@ intvec_\vecname:
mfspr r3, SPR_SYSTEM_SAVE_K_2 /* info about page fault */
.else
.ifc \vecnum, INT_ILL_TRANS
- mfspr r2, ILL_TRANS_REASON
+ mfspr r2, ILL_VA_PC
.else
.ifc \vecnum, INT_DOUBLE_FAULT
mfspr r2, SPR_SYSTEM_SAVE_K_2 /* double fault info from HV */
diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index 5b19a23..a1bbc5de 100644
--- a/arch/tile/kernel/traps.c
+++ b/arch/tile/kernel/traps.c
@@ -222,8 +222,9 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
unsigned long address = 0;
bundle_bits instr;

- /* Re-enable interrupts. */
- local_irq_enable();
+ /* Re-enable interrupts, if they were previously enabled. */
+ if (!(regs->flags & PT_FLAGS_DISABLE_IRQ))
+ local_irq_enable();

/*
* If it hits in kernel mode and we can't fix it up, just exit the
@@ -231,7 +232,8 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
*/
if (!user_mode(regs)) {
const char *name;
- if (fixup_exception(regs)) /* only UNALIGN_DATA in practice */
+ char buf[100];
+ if (fixup_exception(regs)) /* ILL_TRANS or UNALIGN_DATA */
return;
if (fault_num >= 0 &&
fault_num < sizeof(int_name)/sizeof(int_name[0]) &&
@@ -239,10 +241,16 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
name = int_name[fault_num];
else
name = "Unknown interrupt";
- pr_alert("Kernel took bad trap %d (%s) at PC %#lx\n",
- fault_num, name, regs->pc);
if (fault_num == INT_GPV)
- pr_alert("GPV_REASON is %#lx\n", reason);
+ snprintf(buf, sizeof(buf), "; GPV_REASON %#lx", reason);
+#ifdef __tilegx__
+ else if (fault_num == INT_ILL_TRANS)
+ snprintf(buf, sizeof(buf), "; address %#lx", reason);
+#endif
+ else
+ buf[0] = '\0';
+ pr_alert("Kernel took bad trap %d (%s) at PC %#lx%s\n",
+ fault_num, name, regs->pc, buf);
show_regs(regs);
do_exit(SIGKILL); /* FIXME: implement i386 die() */
return;
@@ -324,11 +332,8 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
fill_ra_stack();

signo = SIGSEGV;
+ address = reason;
code = SEGV_MAPERR;
- if (reason & SPR_ILL_TRANS_REASON__I_STREAM_VA_RMASK)
- address = regs->pc;
- else
- address = 0; /* FIXME: GX: single-step for address */
break;
}
#endif
--
1.8.3.1

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