On 2017/09/20 03:49PM, Kamalesh Babulal wrote: > While running stress test with livepatch module loaded, kernel > bug was triggered. > > cpu 0x5: Vector: 400 (Instruction Access) at [c0000000eb9d3b60] > pc: c0000000eb9d3e30 > lr: c0000000eb9d3e30 > sp: c0000000eb9d3de0 > msr: 800000001280b033 > current = 0xc0000000dbd38700 > paca = 0xc00000000fe01400 softe: 0 irq_happened: 0x01 > pid = 8618, comm = make > Linux version 4.13.0+ (root@ubuntu) (gcc version 6.3.0 20170406 (Ubuntu > 6.3.0-12ubuntu2)) #1 SMP Wed Sep 13 03:49:27 EDT 2017 > > 5:mon> t > [c0000000eb9d3de0] c0000000eb9d3e30 (unreliable) > [c0000000eb9d3e30] c000000000008ab4 hardware_interrupt_common+0x114/0x120 > --- Exception: 501 (Hardware Interrupt) at c000000000053040 > livepatch_handler+0x4c/0x74 > [c0000000eb9d4120] 0000000057ac6e9d (unreliable) > [d0000000089d9f78] 2e0965747962382e > SP (965747962342e09) is in userspace > > When an interrupt is served in between the livepatch_handler execution, > there are chances of the livepatch_stack/task task getting corrupted. > > CPU 1 > ============= > Task A Interrupt Handler > ========= ================= > livepatch_handler: > mr r0, r1 > ld r1, TI_livepatch_sp(r12) > hardware_interrupt_common > |_do_IRQ > |_ call_do_irq: > mflr r0 > std r0,16(r1) > stdu > r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4) > ... > lis r2, STACK_END_MAGIC@h > ori r2, r2, STACK_END_MAGIC@l > ld r12, -8(r1) <- livepatch stack is corrupted. > > Fix the corruption by using r11 register for livepatch stack manipulation, > instead of shuffling task stack and livepatch stack into r1 register. > Using r11 register also avoids disabling/enabling irq's while setting > up the livepatch stack. > > Signed-off-by: Kamalesh Babulal <kamal...@linux.vnet.ibm.com> > Cc: Balbir Singh <bsinghar...@gmail.com> > Cc: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> > Cc: linuxppc-dev@lists.ozlabs.org > --- > arch/powerpc/kernel/trace/ftrace_64_mprofile.S | 45 > +++++++++----------------- > 1 file changed, 15 insertions(+), 30 deletions(-)
Reviewed-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> - Naveen
