On 06/09/2014 19:52, Gaël PORTAY : > Hi every one, > > This set of patches fix a segmentation fault happening when kexec-ing > kernel on an at91 platform (see backtrace below). > > While the previous kernel shuts down, the tcb_clksrc driver leaves its > interruptions unmasked. When the new kernel initiliazes any tclib making use > of > a TC block, an interruption may happen before the interrupt handler is set, > causing a kernel segmentation fault. > > To prevent from such cases from happening, the last patch sets up the shutdown > callback which masks interruptions when the machine is shutdown. Furthermore, > it also masks the interruptions at probe to make sure no interruption happens > before the handler is set. This will prevent freshly kexec-ed kernel from > crashing when launched from a kernel which does not properly mask > interruptions > at shutdown. > > Unable to handle kernel NULL pointer dereference at virtual address 00000000 > pgd = c0004000 > [00000000] *pgd=00000000 > Internal error: Oops: 80000005 [#1] ARM > Modules linked in: > CPU: 0 PID: 1 Comm: swapper Not tainted 3.16.0+ #144 > task: c1828aa0 ti: c182a000 task.ti: c182a000 > PC is at 0x0 > LR is at ch2_irq+0x28/0x30 > pc : [<00000000>] lr : [<c01db904>] psr: 000000d3 > sp : c182bd38 ip : c182bd48 fp : c182bd44 > r10: c0373390 r9 : c1825b00 r8 : 60000053 > r7 : 00000000 r6 : 00000000 r5 : 00000013 r4 : c036e800 > r3 : 00000000 r2 : 00002004 r1 : c036e760 r0 : c036e760 > Flags: nzcv IRQs off FIQs off Mode SVC_32 ISA ARM Segment kernel > Control: 0005317f Table: 20004000 DAC: 00000017 > Process swapper (pid: 1, stack limit = 0xc182a1c0) > Stack: (0xc182bd38 to 0xc182c000) > bd20: c182bd7c c182bd48 > bd40: c0045430 c01db8ec 00000000 c18c6f40 c182bd74 c1825b00 c035cec4 00000000 > bd60: c182be2c 60000053 c1825b34 00000000 c182bd94 c182bd80 c0045570 c0045408 > bd80: 00000000 c1825b00 c182bdac c182bd98 c0047f34 c0045550 00000013 c036619c > bda0: c182bdc4 c182bdb0 c0044da4 c0047e98 0000007f 00000013 c182bde4 c182bdc8 > bdc0: c0009e34 c0044d8c fefff000 c0046728 60000053 ffffffff c182bdf4 c182bde8 > bde0: c00086a8 c0009ddc c182be74 c182bdf8 c000cb80 c0008674 00000000 00000013 > be00: 00000000 00014200 c1825b00 c036e800 00000013 c035ed98 60000053 c1825b34 > be20: 00000000 c182be74 c182be20 c182be40 c0047994 c0046728 60000053 ffffffff > be40: 00000013 c036e800 c182be64 c1825b00 00000013 c036e800 c035ed98 c03874bc > be60: 00000004 c036e700 c182be94 c182be78 c004689c c0046398 c036e760 c18c6080 > be80: 00000000 c035ed10 c182bedc c182be98 c0348b08 c004684c 0000000c c034dac8 > bea0: 004c4b3f c028c338 c036e760 00000013 c014ecc8 c18e67e0 c035b9c0 c0348884 > bec0: c035b9c0 c182a020 00000000 00000000 c182bf54 c182bee0 c00089fc c0348894 > bee0: c00da51c c1ffcc78 c182bf0c c182bef8 c002d100 c002d09c c1ffcc78 00000000 > bf00: c182bf54 c182bf10 c002d308 c0336570 c182bf3c c0334e44 00000003 00000003 > bf20: 00000030 c0334b44 c0044d74 00000003 00000003 c034dac8 c0350a94 c0373440 > bf40: c0373440 00000030 c182bf94 c182bf58 c0336d24 c000890c 00000003 00000003 > bf60: c0336560 c182bf64 c182bf64 6e616e0d 00000000 c0272fc8 00000000 00000000 > bf80: 00000000 00000000 c182bfac c182bf98 c0272fd8 c0336bd8 c182a000 00000000 > bfa0: 00000000 c182bfb0 c00095d0 c0272fd8 00000000 00000000 00000000 00000000 > bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 374d27cd 33cc33e4 > Backtrace: > [<c01db8dc>] (ch2_irq) from [<c0045430>] (handle_irq_event_percpu+0x38/0x148) > [<c00453f8>] (handle_irq_event_percpu) from [<c0045570>] > (handle_irq_event+0x30/0x40) > r10:00000000 r9:c1825b34 r8:60000053 r7:c182be2c r6:00000000 r5:c035cec4 > r4:c1825b00 > [<c0045540>] (handle_irq_event) from [<c0047f34>] > (handle_fasteoi_irq+0xac/0x11c) > r4:c1825b00 r3:00000000 > [<c0047e88>] (handle_fasteoi_irq) from [<c0044da4>] > (generic_handle_irq+0x28/0x38) > r5:c036619c r4:00000013 > [<c0044d7c>] (generic_handle_irq) from [<c0009e34>] (handle_IRQ+0x68/0x88) > r4:00000013 r3:0000007f > [<c0009dcc>] (handle_IRQ) from [<c00086a8>] (at91_aic_handle_irq+0x44/0x4c) > r6:ffffffff r5:60000053 r4:c0046728 r3:fefff000 > [<c0008664>] (at91_aic_handle_irq) from [<c000cb80>] (__irq_svc+0x40/0x4c) > Exception stack(0xc182bdf8 to 0xc182be40) > bde0: 00000000 00000013 > be00: 00000000 00014200 c1825b00 c036e800 00000013 c035ed98 60000053 c1825b34 > be20: 00000000 c182be74 c182be20 c182be40 c0047994 c0046728 60000053 ffffffff > [<c0046388>] (__setup_irq) from [<c004689c>] (setup_irq+0x60/0x8c) > r10:c036e700 r9:00000004 r8:c03874bc r7:c035ed98 r6:c036e800 r5:00000013 > r4:c1825b00 > [<c004683c>] (setup_irq) from [<c0348b08>] (tcb_clksrc_init+0x284/0x31c) > r6:c035ed10 r5:00000000 r4:c18c6080 r3:c036e760 > [<c0348884>] (tcb_clksrc_init) from [<c00089fc>] (do_one_initcall+0x100/0x1b4) > r10:00000000 r9:00000000 r8:c182a020 r7:c035b9c0 r6:c0348884 r5:c035b9c0 > r4:c18e67e0 > [<c00088fc>] (do_one_initcall) from [<c0336d24>] > (kernel_init_freeable+0x15c/0x224) > r9:00000030 r8:c0373440 r7:c0373440 r6:c0350a94 r5:c034dac8 r4:00000003 > [<c0336bc8>] (kernel_init_freeable) from [<c0272fd8>] (kernel_init+0x10/0xec) > r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c0272fc8 r4:00000000 > [<c0272fc8>] (kernel_init) from [<c00095d0>] (ret_from_fork+0x14/0x24) > r4:00000000 r3:c182a000 > Code: bad PC value > ---[ end trace 5b30f0017e282e47 ]--- > Kernel panic - not syncing: Fatal exception in interrupt > > Your sincerly, > Gaël PORTAY > > Changes since v1: > - use writel instead of __raw_writel > - move to request_irq function > - disable clock if request irq fails > Changes since v2: > - create dedicated macro to define all IRQs > - use new ATMEL_TC_ALL_IRQ macro to mask all IRQs (instead of 0xff) > - change the fourth patch commit message > Changes since v3: > - fix typo extra space between function name and the parenthesis > > Gaël PORTAY (4): > ARM: at91/tclib: prefer using of devm_* functions > ARM: at91/tclib: move initialization from alloc to probe > ARM: at91/tclib: mask interruptions at shutdown and probe > clocksource: tcb_clksrc: sanitize IRQ request
Thanks a lot Gaël for this bug fix and cleanup! Acked-by: Nicolas Ferre <nicolas.fe...@atmel.com> The series is ready for inclusion in our next kernel release and I integrate it on top of at91-3.18-cleanup2 branch. Best regards, > drivers/clocksource/tcb_clksrc.c | 15 ++---- > drivers/misc/atmel_tclib.c | 101 > +++++++++++++++++---------------------- > drivers/pwm/pwm-atmel-tcb.c | 2 +- > include/linux/atmel_tc.h | 13 +++-- > 4 files changed, 60 insertions(+), 71 deletions(-) > -- Nicolas Ferre -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/