On Tue, 2020-02-18 at 19:38:27 UTC, Christophe Leroy wrote:
> When a program check exception happens while MMU translation is
> disabled, following Oops happens in kprobe_handler() in the following
> code:
>
> } else if (*addr != BREAKPOINT_INSTRUCTION) {
>
> [ 33.098554] BUG: Unable to handle kernel data access on read at 0x0000e268
> [ 33.105091] Faulting instruction address: 0xc000ec34
> [ 33.110010] Oops: Kernel access of bad area, sig: 11 [#1]
> [ 33.115348] BE PAGE_SIZE=16K PREEMPT CMPC885
> [ 33.119540] Modules linked in:
> [ 33.122591] CPU: 0 PID: 429 Comm: cat Not tainted
> 5.6.0-rc1-s3k-dev-00824-g84195dc6c58a #3267
> [ 33.131005] NIP: c000ec34 LR: c000ecd8 CTR: c019cab8
> [ 33.136002] REGS: ca4d3b58 TRAP: 0300 Not tainted
> (5.6.0-rc1-s3k-dev-00824-g84195dc6c58a)
> [ 33.144324] MSR: 00001032 <ME,IR,DR,RI> CR: 2a4d3c52 XER: 00000000
> [ 33.150699] DAR: 0000e268 DSISR: c0000000
> [ 33.150699] GPR00: c000b09c ca4d3c10 c66d0620 00000000 ca4d3c60 00000000
> 00009032 00000000
> [ 33.150699] GPR08: 00020000 00000000 c087de44 c000afe0 c66d0ad0 100d3dd6
> fffffff3 00000000
> [ 33.150699] GPR16: 00000000 00000041 00000000 ca4d3d70 00000000 00000000
> 0000416d 00000000
> [ 33.150699] GPR24: 00000004 c53b6128 00000000 0000e268 00000000 c07c0000
> c07bb6fc ca4d3c60
> [ 33.188015] NIP [c000ec34] kprobe_handler+0x128/0x290
> [ 33.192989] LR [c000ecd8] kprobe_handler+0x1cc/0x290
> [ 33.197854] Call Trace:
> [ 33.200340] [ca4d3c30] [c000b09c] program_check_exception+0xbc/0x6fc
> [ 33.206590] [ca4d3c50] [c000e43c] ret_from_except_full+0x0/0x4
> [ 33.212392] --- interrupt: 700 at 0xe268
> [ 33.270401] Instruction dump:
> [ 33.273335] 913e0008 81220000 38600001 3929ffff 91220000 80010024 bb410008
> 7c0803a6
> [ 33.280992] 38210020 4e800020 38600000 4e800020 <813b0000> 6d2a7fe0
> 2f8a0008 419e0154
> [ 33.288841] ---[ end trace 5b9152d4cdadd06d ]---
>
> kprobe is not prepared to handle events in real mode and functions
> running in real mode should have been blacklisted, so kprobe_handler()
> can safely bail out telling 'this trap is not mine' for any trap that
> happened while in real-mode.
>
> If the trap happened with MSR_IR or MSR_DR cleared, return 0 immediately.
>
> Reported-by: Larry Finger <larry.fin...@lwfinger.net>
> Fixes: 6cc89bad60a6 ("powerpc/kprobes: Invoke handlers directly")
> Cc: sta...@vger.kernel.org
> Cc: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
> Cc: Masami Hiramatsu <mhira...@kernel.org>
> Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/21f8b2fa3ca5b01f7a2b51b89ce97a3705a15aa0
cheers
