We process signals in the end of syscall/exception handler.
If the signal is fatal we print register's content using
show_regs function. show_regs() also prints information about
last exception happened.
In case of multicore system we can catch the situation when we
will print wrong information about exception. See the example:
______________________________
CPU-0: started to handle page fault
CPU-1: sent signal to process, which is executed on CPU-0
CPU-0: ended page fault handle. Started to process signal before
returnig to userspace. Process signal, which is send from
CPU-0. As th signal is fatal we call show_regs().
show_regs() will show information about last exception
which is *page fault* (instead of "trap" which is used for
signals and happened on CPU-0)
So we will get message like this:
# ./waitpid02
potentially unexpected fatal signal 8.
Path: /home/waitpid02
CPU: 0 PID: 100 Comm: waitpid02 Not tainted 4.10.0-rc4 #2
task: 9f11c200 task.stack: 9f3ae000
[ECR ]: 0x00050200 => Invalid Write @ 0x00000000 by insn @ 0x000123ec
[EFA ]: 0x00000000
[BLINK ]: 0x123ea
[ERET ]: 0x123ec
@off 0x123ec in [/home/waitpid02]
VMA: 0x00010000 to 0x00016000
[STAT32]: 0x80080882 : IE U
BTA: 0x000123ea SP: 0x5ffd3db0 FP: 0x00000000
LPS: 0x20031684 LPE: 0x2003169a LPC: 0x00000006
[-----other-info-----]
This message is confusing because it show information about page fault
( [ECR ]: 0x00050200 => Invalid Write ) which is absolutely irrelevant
to signal.
This situation was reproduced with waitpid02 LTP test.
_____________________________
So remove printing information about exceptions from show_regs()
to avoid confusing messages. Print information about exceptions
only in required places instead of show_regs()
Now we don't print information about exceptions if signal is simply
send by another userspace app. So in case of waitpid02 we will print
next message:
_____________________________
# ./waitpid02
potentially unexpected fatal signal 8.
Path: /root/waitpid02
CPU: 2 PID: 105 Comm: waitpid02 Not tainted 4.18.0-rc8-00002-gde0f6d6aeb53-dirty #17
[ECR ]: 0x00050100
[EFA ]: 0x00000000
[BLINK ]: 0x20001486
[-----other-info-----]
_____________________________
This patch fix
STAR 9001146055: waitpid02: Invalid Write @ 0x00000000 by insn @ 0x000123ec
NOTE:
To be more clear I give examples of different faults (signal-based,
userspace/kernelspace exception-based) with different values of
"/proc/sys/kernel/print-fatal-signals" option.
0) NULL pointer access from user space, print-fatal-signals == 1:
------------>8---------------
# ./arc_hell
Exception: arc_hell[103]: at 0x2003a35c [off 0x2e35c in /lib/libuClibc-1.0.18.so, VMA: 2000c000:20072000]
ECR: 0x00050100 => Invalid Read @ 0x00000000 by insn @ 0x2003a35c
potentially unexpected fatal signal 11.
Path: /root/arc_hell
CPU: 1 PID: 103 Comm: arc_hell Not tainted 4.18.0-rc8-00002-gde0f6d6aeb53-dirty #17
[ECR ]: 0x00050100
[EFA ]: 0x00000000
[BLINK ]: 0x20039ef8
[ERET ]: 0x2003a35c
[STAT32]: 0x80080882 : IE U
BTA: 0x2003a358 SP: 0x5fa27dc4 FP: 0x5fa27de8
LPS: 0x2003a628 LPE: 0x2003a62c LPC: 0x00000000
r00: 0x00000000 r01: 0x200740b0 r02: 0x00000001
r03: 0x00000007 r04: 0x80808080 r05: 0x2f2f2f2f
r06: 0x7c7a2f43 r07: 0x00000000 r08: 0x1a131100
r09: 0x2008b1e0 r10: 0x20003a5c r11: 0x20004038
r12: 0x20039ef8 r13: 0x200740b0 r14: 0x00000000
r15: 0x200740b0 r16: 0x00000000 r17: 0x0007d468
r18: 0x0009313a r19: 0x00000000 r20: 0x0009c22c
r21: 0x0009c23c r22: 0x0009ab64 r23: 0x00000000
r24: 0x0009dfc5 r25: 0x20004b70
Segmentation fault
------------>8---------------
1) NULL pointer access from user space, print-fatal-signals == 0:
------------>8---------------
# ./arc_hell
Exception: arc_hell[107]: at 0x2003a35c [off 0x2e35c in /lib/libuClibc-1.0.18.so, VMA: 2000c000:20072000]
ECR: 0x00050100 => Invalid Read @ 0x00000000 by insn @ 0x2003a35c
Segmentation fault
------------>8---------------
2) Process killed by signal (waitpid02 test), print-fatal-signals == 1:
------------>8---------------
# ./waitpid02
potentially unexpected fatal signal 8.
Path: /root/waitpid02
CPU: 2 PID: 105 Comm: waitpid02 Not tainted 4.18.0-rc8-00002-gde0f6d6aeb53-dirty #17
[ECR ]: 0x00050100
[EFA ]: 0x00000000
[BLINK ]: 0x20001486
[ERET ]: 0x2000146c
[STAT32]: 0x80080082 : IE U
BTA: 0x20000fc4 SP: 0x5fa21d64 FP: 0x00000000
LPS: 0x200524a0 LPE: 0x200524b6 LPC: 0x00000006
r00: 0x2000c0dc r01: 0x00000018 r02: 0x0001159a
r03: 0x00000001 r04: 0x00000000 r05: 0x00000045
r06: 0x0000004e r07: 0x01010101 r08: 0x000000dc
r09: 0x200a31e0 r10: 0x20003a5c r11: 0x20004038
r12: 0x20001486 r13: 0x20004174 r14: 0x07ca2bc0
r15: 0x20004078 r16: 0x00000000 r17: 0x20004038
r18: 0x00000001 r19: 0x00000000 r20: 0x0001159a
r21: 0x00000001 r22: 0x00000000 r23: 0x00000004
r24: 0x2000d1fc r25: 0x20004cd0
------------>8---------------
3) Process killed by signal (waitpid02 test), print-fatal-signals == 0:
------------>8---------------
# ./waitpid02
------------>8---------------
4) NULL pointer access from kernel space, regardless print-fatal-signals
value:
------------>8---------------
Oops
Exception: at stmmac_dvr_probe+0x40/0x7e0:
ECR: 0x00050200 => Invalid Write @ 0x00000000 by insn @ 0x90575254
Path: (null)
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.0-rc8-00002-gde0f6d6aeb53-dirty #11
[EFA ]: 0x00000000
[BLINK ]: stmmac_dvr_probe+0x2a/0x7e0
[ERET ]: stmmac_dvr_probe+0x40/0x7e0
[STAT32]: 0x80080402 : IE K
BTA: 0x9057523e SP: 0xbf02be40 FP: 0x00000000
LPS: 0x9073dbcc LPE: 0x9073dbe0 LPC: 0x00000000
r00: 0xbf1f0000 r01: 0x00000000 r02: 0x00000008
r03: 0x00000000 r04: 0x00000064 r05: 0x00000000
r06: 0x00000003 r07: 0x00000004 r08: 0x01010101
r09: 0x00000031 r10: 0xbf1f0006 r11: 0x00000000
r12: 0x9057523e
Stack Trace:
stmmac_dvr_probe+0x40/0x7e0
dwmac_generic_probe+0x50/0xbc
platform_drv_probe+0x26/0x5c
really_probe+0x3b0/0x464
__driver_attach+0xd4/0xd8
bus_for_each_dev+0x3a/0x70
bus_add_driver+0x12a/0x18c
driver_register+0x56/0xe8
do_one_initcall+0x2e/0x118
kernel_init_freeable+0x102/0x194
------------>8---------------
Signed-off-by: Eugeniy Paltsev <[email protected]>
---
Changes v3->v4:
* Rebase onto last ARC changes.
Changes v2->v3:
* Don't show exception message if the corresponding signal is
handled by application (inspired by x86 implementation)
* Rebase onto v4.19-rc8
Changes v1->v2:
* Change format of message about exception.
arch/arc/include/asm/bug.h | 1 +
arch/arc/kernel/traps.c | 3 +++
arch/arc/kernel/troubleshoot.c | 46 ++++++++++++++++++++++++++++++++----------
arch/arc/mm/fault.c | 9 +++++++++
4 files changed, 48 insertions(+), 11 deletions(-)
diff --git a/arch/arc/include/asm/bug.h b/arch/arc/include/asm/bug.h
index 21ec82466d62..b68f7f82f2d8 100644
--- a/arch/arc/include/asm/bug.h
+++ b/arch/arc/include/asm/bug.h
@@ -16,6 +16,7 @@
struct task_struct;
void show_regs(struct pt_regs *regs);
+void show_exception_mesg(struct pt_regs *regs);
void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs);
void show_kernel_fault_diag(const char *str, struct pt_regs *regs,
unsigned long address);
diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
index a7fcbc0d3943..b94b13120bff 100644
--- a/arch/arc/kernel/traps.c
+++ b/arch/arc/kernel/traps.c
@@ -50,6 +50,9 @@ unhandled_exception(const char *str, struct pt_regs *regs,
tsk->thread.fault_address = (__force unsigned int)addr;
+ if (unhandled_signal(tsk, signo))
+ show_exception_mesg(regs);
+
force_sig_fault(signo, si_code, addr, tsk);
} else {
diff --git a/arch/arc/kernel/troubleshoot.c b/arch/arc/kernel/troubleshoot.c
index 215f515442e0..64e9867a1a65 100644
--- a/arch/arc/kernel/troubleshoot.c
+++ b/arch/arc/kernel/troubleshoot.c
@@ -106,13 +106,13 @@ static void show_faulting_vma(unsigned long address)
if (IS_ERR(nm))
nm = "?";
}
- pr_info(" @off 0x%lx in [%s]\n"
- " VMA: 0x%08lx to 0x%08lx\n",
+
+ pr_cont("[off 0x%lx in %s, VMA: %08lx:%08lx] ",
vma->vm_start < TASK_UNMAPPED_BASE ?
address : address - vma->vm_start,
nm, vma->vm_start, vma->vm_end);
} else
- pr_info(" @No matching VMA found\n");
+ pr_cont("[No matching VMA found] ");
up_read(&active_mm->mmap_sem);
}
@@ -122,7 +122,7 @@ static void show_ecr_verbose(struct pt_regs *regs)
unsigned int vec, cause_code;
unsigned long address;
- pr_info("\n[ECR ]: 0x%08lx => ", regs->event);
+ pr_cont("\n ECR: 0x%08lx => ", regs->event);
/* For Data fault, this is data address not instruction addr */
address = current->thread.fault_address;
@@ -170,10 +170,37 @@ static void show_ecr_verbose(struct pt_regs *regs)
}
}
+static inline void show_exception_mesg_u(struct pt_regs *regs)
+{
+ struct task_struct *tsk = current;
+
+ pr_info("Exception: %s[%d]: at %pS ",
+ tsk->comm, task_pid_nr(tsk), (void *)regs->ret);
+
+ show_faulting_vma(regs->ret);
+
+ show_ecr_verbose(regs);
+}
+
+static inline void show_exception_mesg_k(struct pt_regs *regs)
+{
+ pr_info("Exception: at %pS:", (void *)regs->ret);
+
+ show_ecr_verbose(regs);
+}
+
/************************************************************************
* API called by rest of kernel
***********************************************************************/
+void show_exception_mesg(struct pt_regs *regs)
+{
+ if (user_mode(regs))
+ show_exception_mesg_u(regs);
+ else
+ show_exception_mesg_k(regs);
+}
+
void show_regs(struct pt_regs *regs)
{
struct task_struct *tsk = current;
@@ -188,15 +215,10 @@ void show_regs(struct pt_regs *regs)
print_task_path_n_nm(tsk);
show_regs_print_info(KERN_INFO);
- show_ecr_verbose(regs);
-
- pr_info("[EFA ]: 0x%08lx\n[BLINK ]: %pS\n[ERET ]: %pS\n",
- current->thread.fault_address,
+ pr_info("[ECR ]: 0x%08lx\n[EFA ]: 0x%08lx\n[BLINK ]: %pS\n[ERET ]: %pS\n",
+ regs->event, current->thread.fault_address,
(void *)regs->blink, (void *)regs->ret);
- if (user_mode(regs))
- show_faulting_vma(regs->ret); /* faulting code, not data */
-
pr_info("[STAT32]: 0x%08lx", regs->status32);
#define STS_BIT(r, bit) r->status32 & STATUS_##bit##_MASK ? #bit" " : ""
@@ -239,6 +261,8 @@ void show_kernel_fault_diag(const char *str, struct pt_regs *regs,
/* Show fault description */
pr_info("\n%s\n", str);
+ show_exception_mesg(regs);
+
/* Caller and Callee regs */
show_regs(regs);
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 8df1638259f3..e44b64107adb 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -202,7 +202,12 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
tsk->thread.fault_address = address;
+
+ if (unhandled_signal(tsk, SIGSEGV))
+ show_exception_mesg(regs);
+
force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
+
return;
}
@@ -237,5 +242,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
goto no_context;
tsk->thread.fault_address = address;
+
+ if (unhandled_signal(tsk, SIGBUS))
+ show_exception_mesg(regs);
+
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);
}
--
2.14.5
On 1/21/19 9:07 AM, Eugeniy Paltsev wrote:
> We process signals in the end of syscall/exception handler.
> If the signal is fatal we print register's content using
> show_regs function. show_regs() also prints information about
> last exception happened.
>
> In case of multicore system we can catch the situation when we
> will print wrong information about exception. See the example:
> ______________________________
> CPU-0: started to handle page fault
> CPU-1: sent signal to process, which is executed on CPU-0
> CPU-0: ended page fault handle. Started to process signal before
> returnig to userspace. Process signal, which is send from
> CPU-0. As th signal is fatal we call show_regs().
> show_regs() will show information about last exception
> which is *page fault* (instead of "trap" which is used for
> signals and happened on CPU-0)
>
> So we will get message like this:
> # ./waitpid02
> potentially unexpected fatal signal 8.
> Path: /home/waitpid02
> CPU: 0 PID: 100 Comm: waitpid02 Not tainted 4.10.0-rc4 #2
> task: 9f11c200 task.stack: 9f3ae000
>
> [ECR ]: 0x00050200 => Invalid Write @ 0x00000000 by insn @ 0x000123ec
> [EFA ]: 0x00000000
> [BLINK ]: 0x123ea
> [ERET ]: 0x123ec
> @off 0x123ec in [/home/waitpid02]
> VMA: 0x00010000 to 0x00016000
> [STAT32]: 0x80080882 : IE U
> BTA: 0x000123ea SP: 0x5ffd3db0 FP: 0x00000000
> LPS: 0x20031684 LPE: 0x2003169a LPC: 0x00000006
> [-----other-info-----]
>
> This message is confusing because it show information about page fault
> ( [ECR ]: 0x00050200 => Invalid Write ) which is absolutely irrelevant
> to signal.
>
> This situation was reproduced with waitpid02 LTP test.
> _____________________________
>
> So remove printing information about exceptions from show_regs()
> to avoid confusing messages. Print information about exceptions
> only in required places instead of show_regs()
That is fine, but as I mentioned in your last posting, this is still not complete.
If printing reg file confuses us in case of termination by signal from some other
task, I don't see how just leaving out the exception regs, but still printing rest
of the reg file is the complete solution. It is still bogus and any fixes to that
effect are band aids.
>
> Now we don't print information about exceptions if signal is simply
> send by another userspace app. So in case of waitpid02 we will print
> next message:
So all we are skipping is the decoding of ECR as you seem to be printing the raw
value anyways.
> _____________________________
> # ./waitpid02
> potentially unexpected fatal signal 8.
> Path: /root/waitpid02
> CPU: 2 PID: 105 Comm: waitpid02 Not tainted 4.18.0-rc8-00002-gde0f6d6aeb53-dirty #17
> [ECR ]: 0x00050100
> [EFA ]: 0x00000000
> [BLINK ]: 0x20001486
> [-----other-info-----]
> _____________________________
>
> This patch fix
> STAR 9001146055: waitpid02: Invalid Write @ 0x00000000 by insn @ 0x000123ec
>
> NOTE:
> To be more clear I give examples of different faults (signal-based,
> userspace/kernelspace exception-based) with different values of
> "/proc/sys/kernel/print-fatal-signals" option.
>
> 0) NULL pointer access from user space, print-fatal-signals == 1:
> ------------>8---------------
> # ./arc_hell
> Exception: arc_hell[103]: at 0x2003a35c [off 0x2e35c in /lib/libuClibc-1.0.18.so, VMA: 2000c000:20072000]
> ECR: 0x00050100 => Invalid Read @ 0x00000000 by insn @ 0x2003a35c
> potentially unexpected fatal signal 11.
> Path: /root/arc_hell
> CPU: 1 PID: 103 Comm: arc_hell Not tainted 4.18.0-rc8-00002-gde0f6d6aeb53-dirty #17
> [ECR ]: 0x00050100
So we are printing the ECR twice. Sorry this approach is not going to work.
> [EFA ]: 0x00000000
> [BLINK ]: 0x20039ef8
> [ERET ]: 0x2003a35c
...
>
> Segmentation fault
> ------------>8---------------
>
> 1) NULL pointer access from user space, print-fatal-signals == 0:
> ------------>8---------------
> # ./arc_hell
> Exception: arc_hell[107]: at 0x2003a35c [off 0x2e35c in /lib/libuClibc-1.0.18.so, VMA: 2000c000:20072000]
> ECR: 0x00050100 => Invalid Read @ 0x00000000 by insn @ 0x2003a35c
> Segmentation fault
> ------------>8---------------
>
> 2) Process killed by signal (waitpid02 test), print-fatal-signals == 1:
> ------------>8---------------
> # ./waitpid02
> potentially unexpected fatal signal 8.
> Path: /root/waitpid02
> CPU: 2 PID: 105 Comm: waitpid02 Not tainted 4.18.0-rc8-00002-gde0f6d6aeb53-dirty #17
> [ECR ]: 0x00050100
> [EFA ]: 0x00000000
> [BLINK ]: 0x20001486
> [ERET ]: 0x2000146c
> [STAT32]: 0x80080082 : IE U
> BTA: 0x20000fc4 SP: 0x5fa21d64 FP: 0x00000000
> LPS: 0x200524a0 LPE: 0x200524b6 LPC: 0x00000006
> r00: 0x2000c0dc r01: 0x00000018 r02: 0x0001159a
> r03: 0x00000001 r04: 0x00000000 r05: 0x00000045
> r06: 0x0000004e r07: 0x01010101 r08: 0x000000dc
> r09: 0x200a31e0 r10: 0x20003a5c r11: 0x20004038
> r12: 0x20001486 r13: 0x20004174 r14: 0x07ca2bc0
> r15: 0x20004078 r16: 0x00000000 r17: 0x20004038
> r18: 0x00000001 r19: 0x00000000 r20: 0x0001159a
> r21: 0x00000001 r22: 0x00000000 r23: 0x00000004
> r24: 0x2000d1fc r25: 0x20004cd0
This is the part I really object to. We should not print any register when they
are not relevant. Not decoding the ECR is not enough IMO.
> ------------>8---------------
>
> 3) Process killed by signal (waitpid02 test), print-fatal-signals == 0:
> ------------>8---------------
> # ./waitpid02
...
>
> Signed-off-by: Eugeniy Paltsev <[email protected]>
> ---
> Changes v3->v4:
> * Rebase onto last ARC changes.
>
> Changes v2->v3:
> * Don't show exception message if the corresponding signal is
> handled by application (inspired by x86 implementation)
> * Rebase onto v4.19-rc8
>
> Changes v1->v2:
> * Change format of message about exception.
>
> arch/arc/include/asm/bug.h | 1 +
> arch/arc/kernel/traps.c | 3 +++
> arch/arc/kernel/troubleshoot.c | 46 ++++++++++++++++++++++++++++++++----------
> arch/arc/mm/fault.c | 9 +++++++++
> 4 files changed, 48 insertions(+), 11 deletions(-)
>
> diff --git a/arch/arc/include/asm/bug.h b/arch/arc/include/asm/bug.h
> index 21ec82466d62..b68f7f82f2d8 100644
> --- a/arch/arc/include/asm/bug.h
> +++ b/arch/arc/include/asm/bug.h
> @@ -16,6 +16,7 @@
> struct task_struct;
>
> void show_regs(struct pt_regs *regs);
> +void show_exception_mesg(struct pt_regs *regs);
> void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs);
> void show_kernel_fault_diag(const char *str, struct pt_regs *regs,
> unsigned long address);
> diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
> index a7fcbc0d3943..b94b13120bff 100644
> --- a/arch/arc/kernel/traps.c
> +++ b/arch/arc/kernel/traps.c
> @@ -50,6 +50,9 @@ unhandled_exception(const char *str, struct pt_regs *regs,
>
> tsk->thread.fault_address = (__force unsigned int)addr;
>
> + if (unhandled_signal(tsk, signo))
> + show_exception_mesg(regs);
> +
> force_sig_fault(signo, si_code, addr, tsk);
>
> } else {
> diff --git a/arch/arc/kernel/troubleshoot.c b/arch/arc/kernel/troubleshoot.c
> index 215f515442e0..64e9867a1a65 100644
> --- a/arch/arc/kernel/troubleshoot.c
> +++ b/arch/arc/kernel/troubleshoot.c
> @@ -106,13 +106,13 @@ static void show_faulting_vma(unsigned long address)
> if (IS_ERR(nm))
> nm = "?";
> }
> - pr_info(" @off 0x%lx in [%s]\n"
> - " VMA: 0x%08lx to 0x%08lx\n",
> +
> + pr_cont("[off 0x%lx in %s, VMA: %08lx:%08lx] ",
> vma->vm_start < TASK_UNMAPPED_BASE ?
> address : address - vma->vm_start,
> nm, vma->vm_start, vma->vm_end);
> } else
> - pr_info(" @No matching VMA found\n");
> + pr_cont("[No matching VMA found] ");
>
> up_read(&active_mm->mmap_sem);
> }
> @@ -122,7 +122,7 @@ static void show_ecr_verbose(struct pt_regs *regs)
> unsigned int vec, cause_code;
> unsigned long address;
>
> - pr_info("\n[ECR ]: 0x%08lx => ", regs->event);
> + pr_cont("\n ECR: 0x%08lx => ", regs->event);
>
> /* For Data fault, this is data address not instruction addr */
> address = current->thread.fault_address;
> @@ -170,10 +170,37 @@ static void show_ecr_verbose(struct pt_regs *regs)
> }
> }
>
> +static inline void show_exception_mesg_u(struct pt_regs *regs)
> +{
> + struct task_struct *tsk = current;
> +
> + pr_info("Exception: %s[%d]: at %pS ",
> + tsk->comm, task_pid_nr(tsk), (void *)regs->ret);
> +
> + show_faulting_vma(regs->ret);
> +
> + show_ecr_verbose(regs);
> +}
> +
> +static inline void show_exception_mesg_k(struct pt_regs *regs)
> +{
> + pr_info("Exception: at %pS:", (void *)regs->ret);
> +
> + show_ecr_verbose(regs);
> +}
> +
> /************************************************************************
> * API called by rest of kernel
> ***********************************************************************/
>
> +void show_exception_mesg(struct pt_regs *regs)
> +{
> + if (user_mode(regs))
> + show_exception_mesg_u(regs);
> + else
> + show_exception_mesg_k(regs);
> +}
> +
> void show_regs(struct pt_regs *regs)
> {
> struct task_struct *tsk = current;
> @@ -188,15 +215,10 @@ void show_regs(struct pt_regs *regs)
> print_task_path_n_nm(tsk);
> show_regs_print_info(KERN_INFO);
>
> - show_ecr_verbose(regs);
> -
> - pr_info("[EFA ]: 0x%08lx\n[BLINK ]: %pS\n[ERET ]: %pS\n",
> - current->thread.fault_address,
> + pr_info("[ECR ]: 0x%08lx\n[EFA ]: 0x%08lx\n[BLINK ]: %pS\n[ERET ]: %pS\n",
> + regs->event, current->thread.fault_address,
> (void *)regs->blink, (void *)regs->ret);
>
> - if (user_mode(regs))
> - show_faulting_vma(regs->ret); /* faulting code, not data */
> -
> pr_info("[STAT32]: 0x%08lx", regs->status32);
>
> #define STS_BIT(r, bit) r->status32 & STATUS_##bit##_MASK ? #bit" " : ""
> @@ -239,6 +261,8 @@ void show_kernel_fault_diag(const char *str, struct pt_regs *regs,
> /* Show fault description */
> pr_info("\n%s\n", str);
>
> + show_exception_mesg(regs);
> +
> /* Caller and Callee regs */
> show_regs(regs);
>
> diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
> index 8df1638259f3..e44b64107adb 100644
> --- a/arch/arc/mm/fault.c
> +++ b/arch/arc/mm/fault.c
> @@ -202,7 +202,12 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
> /* User mode accesses just cause a SIGSEGV */
> if (user_mode(regs)) {
> tsk->thread.fault_address = address;
> +
> + if (unhandled_signal(tsk, SIGSEGV))
> + show_exception_mesg(regs);
> +
> force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
> +
> return;
> }
>
> @@ -237,5 +242,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
> goto no_context;
>
> tsk->thread.fault_address = address;
> +
> + if (unhandled_signal(tsk, SIGBUS))
> + show_exception_mesg(regs);
> +
> force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);
> }
>