* [PATCH] Fix kgdb on little endian ppc64le
@ 2016-02-01 6:03 Balbir Singh
2016-02-01 10:39 ` Andrew Donnellan
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Balbir Singh @ 2016-02-01 6:03 UTC (permalink / raw)
To: Michael Ellerman; +Cc: Paul Mackerras, kgdb-bugreport, linuxppc-dev
From: Balbir Singh <bsingharora@gmail.com>
I spent some time trying to use kgdb and debugged my inability to
resume from kgdb_handle_breakpoint(). NIP is not incremented
and that leads to a loop in the debugger.
I've tested this lightly on a virtual instance with KDB enabled.
After the patch, I am able to get the "go" command to work as
expected
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
arch/powerpc/kernel/kgdb.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index e77c3cc..92c8f80 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -445,7 +445,11 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
* Global data
*/
struct kgdb_arch arch_kgdb_ops = {
+#ifdef __LITTLE_ENDIAN__
+ .gdb_bpt_instr = {0x08, 0x10, 0x82, 0x7d},
+#else
.gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
+#endif /* __LITTLE_ENDIAN__ */
};
static int kgdb_not_implemented(struct pt_regs *regs)
--
2.5.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] Fix kgdb on little endian ppc64le
2016-02-01 6:03 [PATCH] Fix kgdb on little endian ppc64le Balbir Singh
@ 2016-02-01 10:39 ` Andrew Donnellan
2016-02-01 23:31 ` Balbir Singh
2016-02-09 10:11 ` Michael Ellerman
2016-02-22 9:45 ` Michael Ellerman
2 siblings, 1 reply; 6+ messages in thread
From: Andrew Donnellan @ 2016-02-01 10:39 UTC (permalink / raw)
To: Balbir Singh, Michael Ellerman
Cc: kgdb-bugreport, Paul Mackerras, linuxppc-dev
On 01/02/16 17:03, Balbir Singh wrote:
> From: Balbir Singh <bsingharora@gmail.com>
>
> I spent some time trying to use kgdb and debugged my inability to
> resume from kgdb_handle_breakpoint(). NIP is not incremented
> and that leads to a loop in the debugger.
>
> I've tested this lightly on a virtual instance with KDB enabled.
> After the patch, I am able to get the "go" command to work as
> expected
>
> Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Should this be Cc'd to stable?
--
Andrew Donnellan Software Engineer, OzLabs
andrew.donnellan@au1.ibm.com Australia Development Lab, Canberra
+61 2 6201 8874 (work) IBM Australia Limited
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Fix kgdb on little endian ppc64le
2016-02-01 10:39 ` Andrew Donnellan
@ 2016-02-01 23:31 ` Balbir Singh
0 siblings, 0 replies; 6+ messages in thread
From: Balbir Singh @ 2016-02-01 23:31 UTC (permalink / raw)
To: Andrew Donnellan
Cc: Michael Ellerman, kgdb-bugreport, Paul Mackerras, linuxppc-dev
On Mon, 1 Feb 2016 21:39:00 +1100
Andrew Donnellan <andrew.donnellan@au1.ibm.com> wrote:
> On 01/02/16 17:03, Balbir Singh wrote:
> > From: Balbir Singh <bsingharora@gmail.com>
> >
> > I spent some time trying to use kgdb and debugged my inability to
> > resume from kgdb_handle_breakpoint(). NIP is not incremented
> > and that leads to a loop in the debugger.
> >
> > I've tested this lightly on a virtual instance with KDB enabled.
> > After the patch, I am able to get the "go" command to work as
> > expected
> >
> > Signed-off-by: Balbir Singh <bsingharora@gmail.com>
>
> Should this be Cc'd to stable?
>
>
Good suggestion, Michael? I can repost this to stable if required?
Balbir Singh.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Fix kgdb on little endian ppc64le
2016-02-01 6:03 [PATCH] Fix kgdb on little endian ppc64le Balbir Singh
2016-02-01 10:39 ` Andrew Donnellan
@ 2016-02-09 10:11 ` Michael Ellerman
2016-02-11 6:03 ` Balbir Singh
2016-02-22 9:45 ` Michael Ellerman
2 siblings, 1 reply; 6+ messages in thread
From: Michael Ellerman @ 2016-02-09 10:11 UTC (permalink / raw)
To: Balbir Singh; +Cc: kgdb-bugreport, Paul Mackerras, linuxppc-dev
On Mon, 2016-01-02 at 06:03:25 UTC, Balbir Singh wrote:
> From: Balbir Singh <bsingharora@gmail.com>
>
> I spent some time trying to use kgdb and debugged my inability to
> resume from kgdb_handle_breakpoint(). NIP is not incremented
> and that leads to a loop in the debugger.
>
> I've tested this lightly on a virtual instance with KDB enabled.
> After the patch, I am able to get the "go" command to work as
> expected
The test suite isn't working for me (I think?), so I think maybe we need
something more?
KGDB: Registered I/O driver kgdbts
kgdbts:RUN plant and detach test
Entering kdb (current=0xc0000001fefc0000, pid 1) on processor 12 due to Keyboard Entry
[12]kdb> kgdbts:RUN sw breakpoint test
kgdbts: BP mismatch c00000000018e2cc expected c00000000061c510
KGDB: re-enter exception: ALL breakpoints killed
CPU: 12 PID: 1 Comm: swapper/0 Not tainted 4.5.0-rc3-00006-g893791ee8b01 #5
Call Trace:
[c0000001fb082e10] [c0000000009c4608] dump_stack+0xb0/0xf0 (unreliable)
[c0000001fb082e50] [c00000000018fa8c] kgdb_handle_exception+0x2ac/0x2c0
[c0000001fb082f20] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
[c0000001fb082f50] [c0000000009bcee4] program_check_exception+0x144/0x370
[c0000001fb082fc0] [c000000000006244] program_check_common+0x144/0x180
--- interrupt: 700 at check_and_rewind_pc+0x100/0x130
LR = check_and_rewind_pc+0xfc/0x130
[c0000001fb083340] [c00000000061bfc0] validate_simple_test+0x60/0x170
[c0000001fb083370] [c00000000061c784] run_simple_test+0x194/0x3c0
[c0000001fb0833f0] [c00000000061c17c] kgdbts_put_char+0x4c/0x70
[c0000001fb083420] [c0000000001902e0] put_packet+0x130/0x210
[c0000001fb083470] [c000000000191338] gdb_serial_stub+0x478/0x1110
[c0000001fb083560] [c00000000018f19c] kgdb_cpu_enter+0x3fc/0x800
[c0000001fb083660] [c00000000018f970] kgdb_handle_exception+0x190/0x2c0
[c0000001fb083730] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
[c0000001fb083760] [c0000000009bcee4] program_check_exception+0x144/0x370
[c0000001fb0837d0] [c000000000006244] program_check_common+0x144/0x180
--- interrupt: 700 at kgdb_breakpoint+0x3c/0x70
LR = run_breakpoint_test+0xa4/0x120
[c0000001fb083ac0] [0000000000000000] (null) (unreliable)
[c0000001fb083ae0] [c00000000061d714] run_breakpoint_test+0xa4/0x120
[c0000001fb083b50] [c00000000061dcb4] configure_kgdbts+0x2c4/0x6e0
[c0000001fb083c30] [c00000000000b3d0] do_one_initcall+0xd0/0x250
[c0000001fb083d00] [c000000000cc42f8] kernel_init_freeable+0x270/0x350
[c0000001fb083dc0] [c00000000000bd3c] kernel_init+0x2c/0x150
[c0000001fb083e30] [c0000000000095b0] ret_from_kernel_thread+0x5c/0xac
Kernel panic - not syncing: Recursive entry to debugger
CPU: 12 PID: 1 Comm: swapper/0 Not tainted 4.5.0-rc3-00006-g893791ee8b01 #5
Call Trace:
[c0000001fb082d70] [c0000000009c4608] dump_stack+0xb0/0xf0 (unreliable)
[c0000001fb082db0] [c0000000009c2edc] panic+0x138/0x300
[c0000001fb082e50] [c00000000018fa9c] kgdb_handle_exception+0x2bc/0x2c0
[c0000001fb082f20] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
[c0000001fb082f50] [c0000000009bcee4] program_check_exception+0x144/0x370
[c0000001fb082fc0] [c000000000006244] program_check_common+0x144/0x180
--- interrupt: 700 at check_and_rewind_pc+0x100/0x130
LR = check_and_rewind_pc+0xfc/0x130
[c0000001fb083340] [c00000000061bfc0] validate_simple_test+0x60/0x170
[c0000001fb083370] [c00000000061c784] run_simple_test+0x194/0x3c0
[c0000001fb0833f0] [c00000000061c17c] kgdbts_put_char+0x4c/0x70
[c0000001fb083420] [c0000000001902e0] put_packet+0x130/0x210
[c0000001fb083470] [c000000000191338] gdb_serial_stub+0x478/0x1110
[c0000001fb083560] [c00000000018f19c] kgdb_cpu_enter+0x3fc/0x800
[c0000001fb083660] [c00000000018f970] kgdb_handle_exception+0x190/0x2c0
[c0000001fb083730] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
[c0000001fb083760] [c0000000009bcee4] program_check_exception+0x144/0x370
[c0000001fb0837d0] [c000000000006244] program_check_common+0x144/0x180
--- interrupt: 700 at kgdb_breakpoint+0x3c/0x70
LR = run_breakpoint_test+0xa4/0x120
[c0000001fb083ac0] [0000000000000000] (null) (unreliable)
[c0000001fb083ae0] [c00000000061d714] run_breakpoint_test+0xa4/0x120
[c0000001fb083b50] [c00000000061dcb4] configure_kgdbts+0x2c4/0x6e0
[c0000001fb083c30] [c00000000000b3d0] do_one_initcall+0xd0/0x250
[c0000001fb083d00] [c000000000cc42f8] kernel_init_freeable+0x270/0x350
[c0000001fb083dc0] [c00000000000bd3c] kernel_init+0x2c/0x150
[c0000001fb083e30] [c0000000000095b0] ret_from_kernel_thread+0x5c/0xac
Rebooting in 10 seconds..
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Fix kgdb on little endian ppc64le
2016-02-09 10:11 ` Michael Ellerman
@ 2016-02-11 6:03 ` Balbir Singh
0 siblings, 0 replies; 6+ messages in thread
From: Balbir Singh @ 2016-02-11 6:03 UTC (permalink / raw)
To: Michael Ellerman; +Cc: kgdb-bugreport, Paul Mackerras, linuxppc-dev
On Tue, 2016-02-09 at 21:11 +1100, Michael Ellerman wrote:
> On Mon, 2016-01-02 at 06:03:25 UTC, Balbir Singh wrote:
> > From: Balbir Singh <bsingharora@gmail.com>
> >
> > I spent some time trying to use kgdb and debugged my inability to
> > resume from kgdb_handle_breakpoint(). NIP is not incremented
> > and that leads to a loop in the debugger.
> >
> > I've tested this lightly on a virtual instance with KDB enabled.
> > After the patch, I am able to get the "go" command to work as
> > expected
>
> The test suite isn't working for me (I think?), so I think maybe we need
> something more?
>
>
> KGDB: Registered I/O driver kgdbts
> kgdbts:RUN plant and detach test
>
> Entering kdb (current=0xc0000001fefc0000, pid 1) on processor 12 due to
> Keyboard Entry
> [12]kdb> kgdbts:RUN sw breakpoint test
> kgdbts: BP mismatch c00000000018e2cc expected c00000000061c510
> KGDB: re-enter exception: ALL breakpoints killed
> CPU: 12 PID: 1 Comm: swapper/0 Not tainted 4.5.0-rc3-00006-g893791ee8b01 #5
> Call Trace:
> [c0000001fb082e10] [c0000000009c4608] dump_stack+0xb0/0xf0 (unreliable)
> [c0000001fb082e50] [c00000000018fa8c] kgdb_handle_exception+0x2ac/0x2c0
> [c0000001fb082f20] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
> [c0000001fb082f50] [c0000000009bcee4] program_check_exception+0x144/0x370
> [c0000001fb082fc0] [c000000000006244] program_check_common+0x144/0x180
> --- interrupt: 700 at check_and_rewind_pc+0x100/0x130
> LR = check_and_rewind_pc+0xfc/0x130
> [c0000001fb083340] [c00000000061bfc0] validate_simple_test+0x60/0x170
> [c0000001fb083370] [c00000000061c784] run_simple_test+0x194/0x3c0
> [c0000001fb0833f0] [c00000000061c17c] kgdbts_put_char+0x4c/0x70
> [c0000001fb083420] [c0000000001902e0] put_packet+0x130/0x210
> [c0000001fb083470] [c000000000191338] gdb_serial_stub+0x478/0x1110
> [c0000001fb083560] [c00000000018f19c] kgdb_cpu_enter+0x3fc/0x800
> [c0000001fb083660] [c00000000018f970] kgdb_handle_exception+0x190/0x2c0
> [c0000001fb083730] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
> [c0000001fb083760] [c0000000009bcee4] program_check_exception+0x144/0x370
> [c0000001fb0837d0] [c000000000006244] program_check_common+0x144/0x180
> --- interrupt: 700 at kgdb_breakpoint+0x3c/0x70
> LR = run_breakpoint_test+0xa4/0x120
> [c0000001fb083ac0] [0000000000000000] (null) (unreliable)
> [c0000001fb083ae0] [c00000000061d714] run_breakpoint_test+0xa4/0x120
> [c0000001fb083b50] [c00000000061dcb4] configure_kgdbts+0x2c4/0x6e0
> [c0000001fb083c30] [c00000000000b3d0] do_one_initcall+0xd0/0x250
> [c0000001fb083d00] [c000000000cc42f8] kernel_init_freeable+0x270/0x350
> [c0000001fb083dc0] [c00000000000bd3c] kernel_init+0x2c/0x150
> [c0000001fb083e30] [c0000000000095b0] ret_from_kernel_thread+0x5c/0xac
> Kernel panic - not syncing: Recursive entry to debugger
> CPU: 12 PID: 1 Comm: swapper/0 Not tainted 4.5.0-rc3-00006-g893791ee8b01 #5
> Call Trace:
> [c0000001fb082d70] [c0000000009c4608] dump_stack+0xb0/0xf0 (unreliable)
> [c0000001fb082db0] [c0000000009c2edc] panic+0x138/0x300
> [c0000001fb082e50] [c00000000018fa9c] kgdb_handle_exception+0x2bc/0x2c0
> [c0000001fb082f20] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
> [c0000001fb082f50] [c0000000009bcee4] program_check_exception+0x144/0x370
> [c0000001fb082fc0] [c000000000006244] program_check_common+0x144/0x180
> --- interrupt: 700 at check_and_rewind_pc+0x100/0x130
> LR = check_and_rewind_pc+0xfc/0x130
> [c0000001fb083340] [c00000000061bfc0] validate_simple_test+0x60/0x170
> [c0000001fb083370] [c00000000061c784] run_simple_test+0x194/0x3c0
> [c0000001fb0833f0] [c00000000061c17c] kgdbts_put_char+0x4c/0x70
> [c0000001fb083420] [c0000000001902e0] put_packet+0x130/0x210
> [c0000001fb083470] [c000000000191338] gdb_serial_stub+0x478/0x1110
> [c0000001fb083560] [c00000000018f19c] kgdb_cpu_enter+0x3fc/0x800
> [c0000001fb083660] [c00000000018f970] kgdb_handle_exception+0x190/0x2c0
> [c0000001fb083730] [c0000000000405f4] kgdb_handle_breakpoint+0x64/0xa0
> [c0000001fb083760] [c0000000009bcee4] program_check_exception+0x144/0x370
> [c0000001fb0837d0] [c000000000006244] program_check_common+0x144/0x180
> --- interrupt: 700 at kgdb_breakpoint+0x3c/0x70
> LR = run_breakpoint_test+0xa4/0x120
> [c0000001fb083ac0] [0000000000000000] (null) (unreliable)
> [c0000001fb083ae0] [c00000000061d714] run_breakpoint_test+0xa4/0x120
> [c0000001fb083b50] [c00000000061dcb4] configure_kgdbts+0x2c4/0x6e0
> [c0000001fb083c30] [c00000000000b3d0] do_one_initcall+0xd0/0x250
> [c0000001fb083d00] [c000000000cc42f8] kernel_init_freeable+0x270/0x350
> [c0000001fb083dc0] [c00000000000bd3c] kernel_init+0x2c/0x150
> [c0000001fb083e30] [c0000000000095b0] ret_from_kernel_thread+0x5c/0xac
> Rebooting in 10 seconds..
>
I tried the tests with and without my changes and they both fail. I suspect its
broken on ppc64le on which I am testing. The tests require more work to fix.
I'll see if I can find some time to work on them. This patch is independent of
the current breakage
Thanks for testing the patch.
Balbir Singh
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Fix kgdb on little endian ppc64le
2016-02-01 6:03 [PATCH] Fix kgdb on little endian ppc64le Balbir Singh
2016-02-01 10:39 ` Andrew Donnellan
2016-02-09 10:11 ` Michael Ellerman
@ 2016-02-22 9:45 ` Michael Ellerman
2 siblings, 0 replies; 6+ messages in thread
From: Michael Ellerman @ 2016-02-22 9:45 UTC (permalink / raw)
To: Balbir Singh; +Cc: kgdb-bugreport, Paul Mackerras, linuxppc-dev
On Mon, 2016-01-02 at 06:03:25 UTC, Balbir Singh wrote:
> From: Balbir Singh <bsingharora@gmail.com>
>
> I spent some time trying to use kgdb and debugged my inability to
> resume from kgdb_handle_breakpoint(). NIP is not incremented
> and that leads to a loop in the debugger.
>
> I've tested this lightly on a virtual instance with KDB enabled.
> After the patch, I am able to get the "go" command to work as
> expected
>
> Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/94e3d923592fcfe5585c18a0af
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread
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2016-02-01 6:03 [PATCH] Fix kgdb on little endian ppc64le Balbir Singh
2016-02-01 10:39 ` Andrew Donnellan
2016-02-01 23:31 ` Balbir Singh
2016-02-09 10:11 ` Michael Ellerman
2016-02-11 6:03 ` Balbir Singh
2016-02-22 9:45 ` Michael Ellerman
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