kernel.git/arch/powerpc/kernel/kprobes.c, branch linux-4.14.y

powerpc/kprobes: Fix kprobe Oops happens in booke

2021-08-26T12:37:03Z

[ Upstream commit 43e8f76006592cb1573a959aa287c45421066f9c ] When using kprobe on powerpc booke series processor, Oops happens as show bellow: / # echo "p:myprobe do_nanosleep" > /sys/kernel/debug/tracing/kprobe_events / # echo 1 > /sys/kernel/debug/tracing/events/kprobes/myprobe/enable / # sleep 1 [ 50.076730] Oops: Exception in kernel mode, sig: 5 [#1] [ 50.077017] BE PAGE_SIZE=4K SMP NR_CPUS=24 QEMU e500 [ 50.077221] Modules linked in: [ 50.077462] CPU: 0 PID: 77 Comm: sleep Not tainted 5.14.0-rc4-00022-g251a1524293d #21 [ 50.077887] NIP: c0b9c4e0 LR: c00ebecc CTR: 00000000 [ 50.078067] REGS: c3883de0 TRAP: 0700 Not tainted (5.14.0-rc4-00022-g251a1524293d) [ 50.078349] MSR: 00029000 CR: 24000228 XER: 20000000 [ 50.078675] [ 50.078675] GPR00: c00ebdf0 c3883e90 c313e300 c3883ea0 00000001 00000000 c3883ecc 00000001 [ 50.078675] GPR08: c100598c c00ea250 00000004 00000000 24000222 102490c2 bff4180c 101e60d4 [ 50.078675] GPR16: 00000000 102454ac 00000040 10240000 10241100 102410f8 10240000 00500000 [ 50.078675] GPR24: 00000002 00000000 c3883ea0 00000001 00000000 0000c350 3b9b8d50 00000000 [ 50.080151] NIP [c0b9c4e0] do_nanosleep+0x0/0x190 [ 50.080352] LR [c00ebecc] hrtimer_nanosleep+0x14c/0x1e0 [ 50.080638] Call Trace: [ 50.080801] [c3883e90] [c00ebdf0] hrtimer_nanosleep+0x70/0x1e0 (unreliable) [ 50.081110] [c3883f00] [c00ec004] sys_nanosleep_time32+0xa4/0x110 [ 50.081336] [c3883f40] [c001509c] ret_from_syscall+0x0/0x28 [ 50.081541] --- interrupt: c00 at 0x100a4d08 [ 50.081749] NIP: 100a4d08 LR: 101b5234 CTR: 00000003 [ 50.081931] REGS: c3883f50 TRAP: 0c00 Not tainted (5.14.0-rc4-00022-g251a1524293d) [ 50.082183] MSR: 0002f902 CR: 24000222 XER: 00000000 [ 50.082457] [ 50.082457] GPR00: 000000a2 bf980040 1024b4d0 bf980084 bf980084 64000000 00555345 fefefeff [ 50.082457] GPR08: 7f7f7f7f 101e0000 00000069 00000003 28000422 102490c2 bff4180c 101e60d4 [ 50.082457] GPR16: 00000000 102454ac 00000040 10240000 10241100 102410f8 10240000 00500000 [ 50.082457] GPR24: 00000002 bf9803f4 10240000 00000000 00000000 100039e0 00000000 102444e8 [ 50.083789] NIP [100a4d08] 0x100a4d08 [ 50.083917] LR [101b5234] 0x101b5234 [ 50.084042] --- interrupt: c00 [ 50.084238] Instruction dump: [ 50.084483] 4bfffc40 60000000 60000000 60000000 9421fff0 39400402 914200c0 38210010 [ 50.084841] 4bfffc20 00000000 00000000 00000000 <7fe00008> 7c0802a6 7c892378 93c10048 [ 50.085487] ---[ end trace f6fffe98e2fa8f3e ]--- [ 50.085678] Trace/breakpoint trap There is no real mode for booke arch and the MMU translation is always on. The corresponding MSR_IS/MSR_DS bit in booke is used to switch the address space, but not for real mode judgment. Fixes: 21f8b2fa3ca5 ("powerpc/kprobes: Ignore traps that happened in real mode") Signed-off-by: Pu Lehui Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210809023658.218915-1-pulehui@huawei.com Signed-off-by: Sasha Levin

powerpc/kprobes: Ignore traps that happened in real mode

2020-04-24T06:00:47Z

commit 21f8b2fa3ca5b01f7a2b51b89ce97a3705a15aa0 upstream. 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) { BUG: Unable to handle kernel data access on read at 0x0000e268 Faulting instruction address: 0xc000ec34 Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=16K PREEMPT CMPC885 Modules linked in: CPU: 0 PID: 429 Comm: cat Not tainted 5.6.0-rc1-s3k-dev-00824-g84195dc6c58a #3267 NIP: c000ec34 LR: c000ecd8 CTR: c019cab8 REGS: ca4d3b58 TRAP: 0300 Not tainted (5.6.0-rc1-s3k-dev-00824-g84195dc6c58a) MSR: 00001032 CR: 2a4d3c52 XER: 00000000 DAR: 0000e268 DSISR: c0000000 GPR00: c000b09c ca4d3c10 c66d0620 00000000 ca4d3c60 00000000 00009032 00000000 GPR08: 00020000 00000000 c087de44 c000afe0 c66d0ad0 100d3dd6 fffffff3 00000000 GPR16: 00000000 00000041 00000000 ca4d3d70 00000000 00000000 0000416d 00000000 GPR24: 00000004 c53b6128 00000000 0000e268 00000000 c07c0000 c07bb6fc ca4d3c60 NIP [c000ec34] kprobe_handler+0x128/0x290 LR [c000ecd8] kprobe_handler+0x1cc/0x290 Call Trace: [ca4d3c30] [c000b09c] program_check_exception+0xbc/0x6fc [ca4d3c50] [c000e43c] ret_from_except_full+0x0/0x4 --- interrupt: 700 at 0xe268 Instruction dump: 913e0008 81220000 38600001 3929ffff 91220000 80010024 bb410008 7c0803a6 38210020 4e800020 38600000 4e800020 <813b0000> 6d2a7fe0 2f8a0008 419e0154 ---[ 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 Fixes: 6cc89bad60a6 ("powerpc/kprobes: Invoke handlers directly") Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Christophe Leroy Reviewed-by: Masami Hiramatsu Reviewed-by: Naveen N. Rao Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/424331e2006e7291a1bfe40e7f3fa58825f565e1.1582054578.git.christophe.leroy@c-s.fr Signed-off-by: Greg Kroah-Hartman

powerpc/kprobes: Fix call trace due to incorrect preempt count

2018-04-24T07:36:28Z

commit e6e133c47e6bd4d5dac05b35d06634a8e5648615 upstream. Michael Ellerman reported the following call trace when running ftracetest: BUG: using __this_cpu_write() in preemptible [00000000] code: ftracetest/6178 caller is opt_pre_handler+0xc4/0x110 CPU: 1 PID: 6178 Comm: ftracetest Not tainted 4.15.0-rc7-gcc6x-gb2cd1df #1 Call Trace: [c0000000f9ec39c0] [c000000000ac4304] dump_stack+0xb4/0x100 (unreliable) [c0000000f9ec3a00] [c00000000061159c] check_preemption_disabled+0x15c/0x170 [c0000000f9ec3a90] [c000000000217e84] opt_pre_handler+0xc4/0x110 [c0000000f9ec3af0] [c00000000004cf68] optimized_callback+0x148/0x170 [c0000000f9ec3b40] [c00000000004d954] optinsn_slot+0xec/0x10000 [c0000000f9ec3e30] [c00000000004bae0] kretprobe_trampoline+0x0/0x10 This is showing up since OPTPROBES is now enabled with CONFIG_PREEMPT. trampoline_probe_handler() considers itself to be a special kprobe handler for kretprobes. In doing so, it expects to be called from kprobe_handler() on a trap, and re-enables preemption before returning a non-zero return value so as to suppress any subsequent processing of the trap by the kprobe_handler(). However, with optprobes, we don't deal with special handlers (we ignore the return code) and just try to re-enable preemption causing the above trace. To address this, modify trampoline_probe_handler() to not be special. The only additional processing done in kprobe_handler() is to emulate the instruction (in this case, a 'nop'). We adjust the value of regs->nip for the purpose and delegate the job of re-enabling preemption and resetting current kprobe to the probe handlers (kprobe_handler() or optimized_callback()). Fixes: 8a2d71a3f273 ("powerpc/kprobes: Disable preemption before invoking probe handler for optprobes") Cc: stable@vger.kernel.org # v4.15+ Reported-by: Michael Ellerman Signed-off-by: Naveen N. Rao Acked-by: Ananth N Mavinakayanahalli Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/kprobes: Dereference function pointers only if the address does not belong to kernel text

2017-11-01T04:51:03Z

This makes the changes introduced in commit 83e840c770f2c5 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") to be specific to the kprobe subsystem. We previously changed ppc_function_entry() to always check the provided address to confirm if it needed to be dereferenced. This is actually only an issue for kprobe blacklisted asm labels (through use of _ASM_NOKPROBE_SYMBOL) and can cause other issues with ftrace. Also, the additional checks are not really necessary for our other uses. As such, move this check to the kprobes subsystem. Fixes: 83e840c770f2 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") Cc: stable@vger.kernel.org # v4.13+ Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-07-09T17:49:47Z

Pull perf fixes from Thomas Gleixner: "A couple of fixes for perf and kprobes: - Add he missing exclude_kernel attribute for the precise_ip level so !CAP_SYS_ADMIN users get the proper results. - Warn instead of failing completely when perf has no unwind support for a particular architectiure built in. - Ensure that jprobes are at function entry and not at some random place" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: kprobes: Ensure that jprobe probepoints are at function entry kprobes: Simplify register_jprobes() kprobes: Rename [arch_]function_offset_within_entry() to [arch_]kprobe_on_func_entry() perf unwind: Do not fail due to missing unwind support perf evsel: Set attr.exclude_kernel when probing max attr.precise_ip

kprobes: Rename [arch_]function_offset_within_entry() to [arch_]kprobe_on_func_entry()

2017-07-08T09:05:34Z

Rename function_offset_within_entry() to scope it to kprobe namespace by using kprobe_ prefix, and to also simplify it. Suggested-by: Ingo Molnar Suggested-by: Masami Hiramatsu Signed-off-by: Naveen N. Rao Cc: Ananth N Mavinakayanahalli Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/3aa6c7e2e4fb6e00f3c24fa306496a66edb558ea.1499443367.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Ingo Molnar

powerpc/kprobes: Move kprobes over to patch_instruction()

2017-07-03T13:12:19Z

arch_arm/disarm_probe() use direct assignment for copying instructions, replace them with patch_instruction(). We don't need to call flush_icache_range() because patch_instruction() does it for us. Signed-off-by: Balbir Singh Signed-off-by: Michael Ellerman

powerpc/kprobes: Skip livepatch_handler() for jprobes

2017-06-16T09:49:43Z

ftrace_caller() depends on a modified regs->nip to detect if a certain function has been livepatched. However, with KPROBES_ON_FTRACE, it is possible for regs->nip to have been modified by the kprobes pre_handler (jprobes, for instance). In this case, we do not want to invoke the livepatch_handler so as not to consume the livepatch stack. To distinguish between the two (kprobes and livepatch), we check if there is an active kprobe on the current function. If there is, then we know for sure that it must have modified the NIP as we don't support livepatching a kprobe'd function. In this case, we simply skip the livepatch_handler and branch to the new NIP. Otherwise, the livepatch_handler is invoked. Fixes: ead514d5fb30 ("powerpc/kprobes: Add support for KPROBES_ON_FTRACE") Signed-off-by: Naveen N. Rao Reviewed-by: Masami Hiramatsu Signed-off-by: Michael Ellerman

powerpc/kprobes: Pause function_graph tracing during jprobes handling

2017-06-16T09:49:43Z

This fixes a crash when function_graph and jprobes are used together. This is essentially commit 237d28db036e ("ftrace/jprobes/x86: Fix conflict between jprobes and function graph tracing"), but for powerpc. Jprobes breaks function_graph tracing since the jprobe hook needs to use jprobe_return(), which never returns back to the hook, but instead to the original jprobe'd function. The solution is to momentarily pause function_graph tracing before invoking the jprobe hook and re-enable it when returning back to the original jprobe'd function. Fixes: 6794c78243bf ("powerpc64: port of the function graph tracer") Cc: stable@vger.kernel.org # v2.6.30+ Signed-off-by: Naveen N. Rao Acked-by: Masami Hiramatsu Acked-by: Steven Rostedt (VMware) Signed-off-by: Michael Ellerman

powerpc/kprobes: Fix handling of instruction emulation on probe re-entry

2017-05-16T03:11:07Z

Commit 22d8b3dec214c ("powerpc/kprobes: Emulate instructions on kprobe handler re-entry") enabled emulating instructions on kprobe re-entry, rather than single-stepping always. However, we didn't update the single stepping code to only be run if the emulation fails. Also, we missed re-enabling preemption if the instruction emulation was successful. Fix those issues. Fixes: 22d8b3dec214c ("powerpc/kprobes: Emulate instructions on kprobe handler re-entry") Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman