From mboxrd@z Thu Jan 1 00:00:00 1970 From: takahiro.akashi@linaro.org (AKASHI Takahiro) Date: Fri, 13 Nov 2015 14:51:07 +0900 Subject: arm64 function_graph tracer panic with CONFIG_DYNAMIC_FTRACE In-Reply-To: <20151112104243.GF5627@e104818-lin.cambridge.arm.com> References: <20151112104243.GF5627@e104818-lin.cambridge.arm.com> Message-ID: <56457A4B.601@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Catalin, (add lakml back to Cc) On 11/13/2015 01:01 AM, Catalin Marinas wrote: > On Fri, Nov 13, 2015 at 12:00:42AM +0900, AKASHI Takahiro wrote: >> If possible, please try again with "select HAVE_FUNCTION_GRAPH_FP_TEST" added >> to CONFIG_ARM64. >> It will insert an additional check. I hope this will help. > > So it looks the the frame is off by some amount: I was able to reproduce the problem on hikey, too. > # echo function_graph > /sys/kernel/debug/tracing/current_tracer > Bad frame pointer: expected ffffffc976b3bd50, received ffffffc976b3be60 The difference of fp's was 0x110(sizeof(pt_reg_t)=0x120). It seems that an interrupt happened here (and we might have unwound one extra frame?). > from func psci_cpu_suspend return to ffffffc00008d058 Always in the same place. > ------------[ cut here ]------------ > WARNING: at /work/Linux/linux-2.6-aarch64/kernel/trace/trace_functions_graph.c:223 > Modules linked in: > > CPU: 4 PID: 0 Comm: swapper/4 Not tainted 4.3.0+ #584 > Hardware name: Juno (DT) > task: ffffffc976b22f00 ti: ffffffc976b38000 task.ti: ffffffc976b38000 > PC is at ftrace_return_to_handler+0x11c/0x150 > LR is at ftrace_return_to_handler+0x11c/0x150 > pc : [] lr : [] pstate: 800001c5 > sp : ffffffc976b3bdd0 > x29: ffffffc976b3bdd0 x28: ffffffc0006c9000 > x27: ffffffc000a29f20 x26: ffffffc976b3bf70 > x25: 000000cc2c13e054 x24: 0000000000000004 > x23: ffffffc000aeb790 x22: 0000000000000002 > x21: ffffffc975503200 x20: ffffffc000aeb850 > x19: 0000000000000002 x18: ffffffc000b3a920 > x17: 0000000000000000 x16: 0000000000000000 > x15: ffffffc000b3a5bf x14: 3739636666666666 > x13: 6620646576696563 x12: 6572202c30356462 > x11: 3362363739636666 x10: 00000000000000fc > x9 : ffffffc9768070c0 x8 : 0000000000001dd0 > x7 : ffffffc9760f4c80 x6 : ffffffc9760f4c00 > x5 : 00000000000084c0 x4 : 0000000000000001 > x3 : ffffffc976b3bc50 x2 : 0000000000000001 > x1 : 000000000000007f x0 : 000000000000007f > > ---[ end trace ac97c44ba7dabcce ]--- > Call trace: > [] ftrace_return_to_handler+0x11c/0x150 > [] return_to_handler+0x1c/0x40 > [] return_to_handler+0x0/0x40 > [] return_to_handler+0x0/0x40 > [] return_to_handler+0x0/0x40 > [] return_to_handler+0x0/0x40 > [] return_to_handler+0x0/0x40 > [] return_to_handler+0x0/0x40 These call stacks were: (psci_cpu_suspend) psci_suspend_finisher (cpu_suspend_enter?) cpu_suspend cpu_psci_cpu_suspend arm_cpuidle_suspend arm_enter_idle_state cpuidle_enter_state cpuidle_enter call_cpuidle (cpu_startup_entry?) and if cpuidle is turned off(cpuidle.off=1), the panic never happens. That is all what I know at this moment. -Takahiro AKASHI > [] secondary_start_kernel+0x130/0x158 > Unable to handle kernel NULL pointer dereference at virtual address 00000000 > pgd = ffffffc000b68000 > [00000000] *pgd=00000009f69ea003, *pud=00000009f69ea003, *pmd=00000009f69eb003, *pte=006000002c010707 > Internal error: Oops: 96000006 [#1] PREEMPT SMP [snip] On 11/12/2015 07:42 PM, Catalin Marinas wrote: > Hi Takahiro, > > I was trying to assess what's working/not working in ftrace on arm64 and > whether your recent patches are meant for 4.4 or can wait until 4.5. > However, without any patches applied on a 4.3 kernel, enabling the > function_graph tracer when CONFIG_DYNAMIC_FTRACE is enabled panics the > kernel. Strangely, it does not happen if only a single CPU is on. > However, with function_graph tracer on, onlining a second CPU leads to a > similar panic. > > Below is the kernel panic with 2 CPUs online on a Juno board. There > isn't much stack trace information for CPU 5 where the fault happened, > the frame pointer (x29) seems corrupted as well. Any idea? Thanks. > > # echo function_graph > /sys/kernel/debug/tracing/current_tracer > swapper/5[0]: undefined instruction: pc=ffffffc000a46698 > Code: 0009ccf8 ffffffc0 00000000 00000000 (00000030) > Internal error: Oops - undefined instruction: 0 [#1] PREEMPT SMP > Modules linked in: > CPU: 5 PID: 0 Comm: swapper/5 Not tainted 4.3.0 #574 > Hardware name: Juno (DT) > task: ffffffc976b23ac0 ti: ffffffc976b3c000 task.ti: ffffffc976b3c000 > PC is at cpu_online_bits+0x0/0x8 > LR is at cpu_online_bits+0x0/0x8 > pc : [] lr : [] pstate: 600001c5 > sp : ffffffc976b3ff40 > x29: 0000000000000002 x28: ffffffc000100c0c > x27: ffffffc000aeb790 x26: ffffffc9758d5800 > x25: 0000000000000002 x24: ffffffc0000924a0 > x23: ffffffc976b3ff40 x22: ffffffc00056841c > x21: ffffffc000a25b80 x20: ffffffc000aeb790 > x19: ffffffc9758d5800 x18: 0000000000000000 > x17: 0000000000000000 x16: 0000000000000000 > x15: 0000000000000000 x14: 0000000000000000 > x13: 0000000000000000 x12: 0000000034d5d91d > x11: 0000000000000000 x10: 0000000000001000 > x9 : ffffffc9768070c0 x8 : 00000000000007d8 > x7 : 0000001b280eb7c4 x6 : 0000000000000015 > x5 : 000000000000000a x4 : ffffffc0792a4990 > x3 : ffffffffffffffa1 x2 : ffffffc0792a4800 > x1 : ffffffc0000949e0 x0 : ffffffffffffffa1 > > Process swapper/5 (pid: 0, stack limit = 0xffffffc976b3c020) > Stack: (0xffffffc976b3ff40 to 0xffffffc976b40000) > ff40: ffffffc976b3ff70 ffffffc0000924a0 ffffffc976b3c000 ffffffc000a46000 > ff60: ffffffc000b20000 0000001b27d716c0 ffffffc976b3ffd0 ffffffc000090208 > ff80: 0000000000000005 0000000000000e12 ffffffc000b306a0 0000000000000000 > ffa0: 0000000000000000 0000000000000000 0000000080b65000 0000000080b68000 > ffc0: ffffffc0000827f0 0000000000000000 0000000000000000 00000000800827dc > ffe0: 0000000000000000 0000000000000000 068824085611a721 280b8a0b05808446 > Call trace: > Code: 0009ccf8 ffffffc0 00000000 00000000 (00000030) > ---[ end trace 702bb2ed35464601 ]--- > Kernel panic - not syncing: Attempted to kill the idle task! > CPU4: stopping > CPU: 4 PID: 0 Comm: swapper/4 Tainted: G D 4.3.0 #574 > Hardware name: Juno (DT) > Call trace: > [] dump_backtrace+0x0/0x150 > [] show_stack+0x24/0x30 > [] dump_stack+0x90/0xd0 > [] handle_IPI+0x280/0x290 > [] gic_handle_irq+0x94/0xb0 > Exception stack(0xffffffc976b3bd70 to 0xffffffc976b3be90) > bd60: 0000001b2ed1ee8c ffffffc000aeb850 > bd80: ffffffc976b3bec0 ffffffc0005681dc 0000000080000145 ffffffc00009244c > bda0: 0000000000000000 0000000000000001 ffffffc976b38000 0000000000000003 > bdc0: ffffffc976b38000 ffffffc000a282a8 ffffffc976b38000 ffffffc0000ecb28 > bde0: 00000000000006ed ffffffc9768070c0 00000000000007e0 ffffffc0006d04a8 > be00: 0000000000000001 0000000000005a0e 0000000000000001 ffffffc0006d04a8 > be20: 0000000000000000 0000000000000000 0000000000000001 0000001b2ed1ee8c > be40: ffffffc000aeb850 ffffffc9758d5600 0000000000000000 ffffffc000aeb790 > be60: 0000000000000004 0000001b2e40a7ec ffffffc976b3bf70 ffffffc000a29f20 > be80: ffffffc0006c9000 ffffffc976b3bec0 > [] el1_irq+0x6c/0xe0 > [] cpuidle_enter+0x34/0x48 > [] call_cpuidle+0x48/0x80 > [] cpu_startup_entry+0x228/0x308 > [] secondary_start_kernel+0x130/0x158 > ---[ end Kernel panic - not syncing: Attempted to kill the idle task! >