| Message ID | 20160201170325.4ec4324e@cotter.ozlabs.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
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?
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.
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
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
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
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)