On 2017/07/02 10:40PM, Nicholas Piggin wrote: > On Sat, 01 Jul 2017 12:24:02 +1000 > Michael Ellerman <m...@ellerman.id.au> wrote: > > > "Naveen N. Rao" <naveen.n....@linux.vnet.ibm.com> writes: > > > > > Convert some of the symbols into private symbols and blacklist > > > system_call_common() and system_call() from kprobes. We can't take a > > > trap at parts of these functions as either MSR_RI is unset or the kernel > > > stack pointer is not yet setup. > > > > > > Reviewed-by: Masami Hiramatsu <mhira...@kernel.org> > > > Reviewed-by: Nicholas Piggin <npig...@gmail.com> > > > Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> > > > --- > > > arch/powerpc/kernel/entry_64.S | 29 +++++++++++++++-------------- > > > 1 file changed, 15 insertions(+), 14 deletions(-) > > > > > > diff --git a/arch/powerpc/kernel/entry_64.S > > > b/arch/powerpc/kernel/entry_64.S > > > index da9486e2fd89..ef8e6615b8ba 100644 > > > --- a/arch/powerpc/kernel/entry_64.S > > > +++ b/arch/powerpc/kernel/entry_64.S > > > @@ -52,12 +52,11 @@ exception_marker: > > > .section ".text" > > > .align 7 > > > > > > - .globl system_call_common > > > -system_call_common: > > > +_GLOBAL(system_call_common) > > > > Looks good. > > > > Yet ... > > > > Power6: > > > > [ 0.313058] Bad kernel stack pointer 7fffdd061cf0 at c00000000000cd80 > > [ 0.313068] Oops: Bad kernel stack pointer, sig: 6 [#1] > > [ 0.313072] SMP NR_CPUS=2048 > > [ 0.313072] NUMA > > [ 0.313076] pSeries > > [ 0.313081] Modules linked in: > > [ 0.313087] CPU: 1 PID: 1 Comm: init Not tainted > > 4.12.0-rc3-gcc_ubuntu_be-g464970a #1 > > [ 0.313093] task: c000000049480000 task.stack: c0000000494c0000 > > [ 0.313097] NIP: c00000000000cd80 LR: 00007fff8e8a13b0 CTR: > > 00007fff8e8a1370 > > [ 0.313103] REGS: c000000007fa3d40 TRAP: 0300 Not tainted > > (4.12.0-rc3-gcc_ubuntu_be-g464970a) > > [ 0.313108] MSR: 8000000000001032 <SF,ME,IR,DR,RI> > > [ 0.313114] CR: 84000022 XER: 00000000 > > [ 0.313120] CFAR: 00000000000087c0 DAR: 0000000000001e64 DSISR: > > 42000000 SOFTE: 0 > > [ 0.313120] GPR00: 000000000000002d 00007fffdd061cf0 00007fff8e8c8af8 > > 0000000000000000 > > [ 0.313120] GPR04: 00000000000019c0 00007fff8e860000 0000000000000001 > > 00007fff8e8c2a30 > > [ 0.313120] GPR08: 00000000493e1528 0000000000000000 b000000000001032 > > 00007fff8e8a1ea8 > > [ 0.313120] GPR12: 800000000000d032 c000000006b30500 0000000000000000 > > 0000000000000000 > > [ 0.313120] GPR16: 0000000000000000 0000000000000000 0000000000000000 > > 0000000000000000 > > [ 0.313120] GPR20: 0000000000000000 0000000000000000 0000000000000080 > > 0000000000010000 > > [ 0.313120] GPR24: 0000000000000000 00007fffdd0626c9 00000000493a0040 > > 0000000000000009 > > [ 0.313120] GPR28: 00007fff8e8bfe58 00007fff8e8bfb88 00007fff8e8bfe40 > > 00007fff8e8c0148 > > [ 0.313190] NIP [c00000000000cd80] .load_up_vsx+0x1c/0x2c > > [ 0.313195] LR [00007fff8e8a13b0] 0x7fff8e8a13b0 > > [ 0.313199] Call Trace: > > [ 0.313201] Instruction dump: > > [ 0.313206] 7fe721ce 10000604 38800200 7c0439ce 4e800020 71852000 > > 41a2f7c5 75850200 > > [ 0.313217] 41a2fd71 e88d0250 388419c0 38c00001 <90c404a4> 658c0080 > > f9810178 4bffefc4 > > [ 0.313229] ---[ end trace 3ca7930ed36d9399 ]--- > > > > Power7: > > > > [ 1.770801] Bad kernel stack pointer ff9be8b0 at 1f7f79590 > > [ 1.770811] Oops: Bad kernel stack pointer, sig: 6 [#1] > > [ 1.770814] SMP NR_CPUS=2048 > > [ 1.770815] NUMA > > [ 1.770819] pSeries > > [ 1.770825] Modules linked in: > > [ 1.770832] CPU: 26 PID: 1 Comm: init Not tainted > > 4.12.0-rc3-gcc6-g464970a #1 > > [ 1.770838] task: c000000e18300000 task.stack: c000000e18380000 > > [ 1.770843] NIP: 00000001f7f79590 LR: 00000000f7f79358 CTR: > > 00000001f7f79590 > > [ 1.770848] REGS: c00000000ed47d40 TRAP: 0400 Not tainted > > (4.12.0-rc3-gcc6-g464970a) > > [ 1.770853] MSR: 8000000040001032 <SF,ME,IR,DR,RI> > > [ 1.770860] CR: 24000888 XER: 20000000 > > [ 1.770866] CFAR: 00000000000087c0 SOFTE: 0 > > [ 1.770866] GPR00: 00000000f7f7998c 00000000ff9be8b0 0000000000000000 > > 0000000000000000 > > [ 1.770866] GPR04: 00000000f7f9f5b8 0000000000000005 0000000000000072 > > 0000000000000072 > > [ 1.770866] GPR08: fffffffffeff0000 0000000000000000 00000001f7f79590 > > 00000000f7f7ac30 > > [ 1.770866] GPR12: 0000000000000001 c00000000ec08200 0000000000010000 > > 0000000000000000 > > [ 1.770866] GPR16: 00000000ff9bed49 0000000000000000 00000000dc0065c2 > > 0000000000000000 > > [ 1.770866] GPR20: 0000000020000000 0000000000000064 0000000000000001 > > 0000000000000001 > > [ 1.770866] GPR24: 0000000000000001 0000000000000001 00000000f7f62b40 > > 0000000020620034 > > [ 1.770866] GPR28: 000000000000000a 00000000ff9bed49 00000000f7f9fff4 > > 00000000f7f9f308 > > [ 1.770929] NIP [00000001f7f79590] 0x1f7f79590 > > [ 1.770933] LR [00000000f7f79358] 0xf7f79358 > > [ 1.770937] Call Trace: > > [ 1.770940] Instruction dump: > > [ 1.770945] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX > > XXXXXXXX XXXXXXXX > > [ 1.770953] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX > > XXXXXXXX XXXXXXXX > > [ 1.770964] ---[ end trace 4eb52706b24fb9c6 ]--- > > > > Cell: > > > > [ 21.359058] init[1]: unhandled signal 11 at 00000000 nip 00000000 lr > > c00000000000b01c code 30001 > > [ 21.412082] Kernel panic - not syncing: Attempted to kill init! > > exitcode=0x0000000b > > [ 21.412082] > > [ 21.466866] CPU: 1 PID: 1 Comm: init Not tainted > > 4.12.0-rc3-gcc6x-g464970a #1 > > [ 21.509619] Call Trace: > > [ 21.524265] [c0000007fb9838d0] [c000000000440a28] > > .dump_stack+0xa8/0xe8 (unreliable) > > [ 21.570715] [c0000007fb983960] [c0000000001d0258] .panic+0x13c/0x2ec > > [ 21.608787] [c0000007fb983a10] [c0000000000a59c0] .do_exit+0xb88/0xb90 > > [ 21.647945] [c0000007fb983ae0] [c0000000000a6cd4] > > .do_group_exit+0x64/0x100 > > [ 21.689666] [c0000007fb983b70] [c0000000000b5dfc] > > .get_signal+0x3bc/0x748 > > [ 21.730338] [c0000007fb983c70] [c00000000001742c] .do_signal+0x64/0x2b0 > > [ 21.769969] [c0000007fb983db0] [c000000000017870] > > .do_notify_resume+0xc0/0xe8 > > [ 21.812733] [c0000007fb983e30] [c00000000000abb0] > > .ret_from_except_lite+0x5c/0x60 > > [ 21.857649] Rebooting in 180 seconds.. > > > > And G5 too, but I don't have the trace. > > > > Strangely it doesn't break on all my BE systems. I suspect AIL=1 avoids it. > > > > One to investigate on Monday :)
Ugh! I am able to reproduce with CONFIG_RELOCATABLE... > > .type system_call_common,@function > > Seems to make the linker resolve system_call_common to address of its > function descriptor. I guess the load handler macros should be using > DOTSYM()? Thanks for looking into this, Nick. That does seem to be the problem. The below patch fixes it for me: diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 20318ceeea6a..0b64c543cdc7 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -862,7 +862,7 @@ EXC_COMMON(trap_0b_common, 0xb00, unknown_exception) #endif #define LOAD_SYSCALL_HANDLER(reg) \ - __LOAD_HANDLER(reg, system_call_common) + __LOAD_HANDLER(reg, DOTSYM(system_call_common)) #define SYSCALL_FASTENDIAN_TEST \ BEGIN_FTR_SECTION \ We can't convert all of __LOAD_HANDLER() since others' use assembly symbols defined through EXC_COMMON_BEGIN(), which doesn't have the function annotation. Michael, Let me know how you want to proceed with this. We can drop the conversion to _GLOBAL() from this series, or I can put out a separate patch to do just that (including the above hunk) and re-send. Thanks, Naveen