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708b1376 |
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05-Mar-2022 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: avoid duplicated unwinding entries for kretprobes Currently when unwinding starts from pt_regs or encounters pt_regs along the way unwinder tries to yield 2 unwinding entries: 1. (reliable) ip1: pt_regs->psw.addr, sp1: regs->gprs[15] 2. (non-reliable) ip2: sp1->gprs[8] (r14), sp2: regs->gprs[15] In case of kretprobes those are identical and serves no other purpose than causing confusion over duplicated entries and cause kprobes tests to fail. So, skip a duplicate non-reliable entry in this case. With that kretprobes and unwinder implementation now comply with ARCH_CORRECT_STACKTRACE_ON_KRETPROBE. Reviewed-by: Tobias Huschle <huschle@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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d81675b6 |
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28-Apr-2021 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: recover kretprobe modified return address in stacktrace Based on commit cd9bc2c92588 ("arm64: Recover kretprobe modified return address in stacktrace"). """ Since the kretprobe replaces the function return address with the __kretprobe_trampoline on the stack, stack unwinder shows it instead of the correct return address. This checks whether the next return address is the __kretprobe_trampoline(), and if so, try to find the correct return address from the kretprobe instance list. """ Original patch series: https://lore.kernel.org/all/163163030719.489837.2236069935502195491.stgit@devnote2/ Reviewed-by: Tobias Huschle <huschle@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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eef06cbf |
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11-Dec-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: stop gracefully at user mode pt_regs in irq stack Consider reaching user mode pt_regs at the bottom of irq stack graceful unwinder termination. This is the case when irq/mcck/ext interrupt arrives while in user mode. Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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be2d11b2 |
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27-Nov-2019 |
Miroslav Benes <mbenes@suse.cz> |
s390/unwind: add stack pointer alignment sanity checks ABI requires SP to be aligned 8 bytes, report unwinding error otherwise. Link: https://lkml.kernel.org/r/20191106095601.29986-5-mbenes@suse.cz Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Tested-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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bf018ee6 |
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27-Nov-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: filter out unreliable bogus %r14 Currently unwinder unconditionally returns %r14 from the first frame pointed by %r15 from pt_regs. A task could be interrupted when a function already allocated this frame (if it needs it) for its callees or to store local variables. In that case this frame would contain random values from stack or values stored there by a callee. As we are only interested in %r14 to get potential return address, skip bogus return addresses which doesn't belong to kernel text. This helps to avoid duplicating filtering logic in unwider users, most of which use unwind_get_return_address() and would choke on bogus 0 address returned by it otherwise. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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222ee908 |
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27-Nov-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: start unwinding from reliable state A comment in arch/s390/include/asm/unwind.h says: > If 'first_frame' is not zero unwind_start skips unwind frames until it > reaches the specified stack pointer. > The end of the unwinding is indicated with unwind_done, this can be true > right after unwind_start, e.g. with first_frame!=0 that can not be found. > unwind_next_frame skips to the next frame. > Once the unwind is completed unwind_error() can be used to check if there > has been a situation where the unwinder could not correctly understand > the tasks call chain. With this change backchain unwinder now comply with behaviour described. As well as matches orc unwinder implementation. Now unwinder starts from reliable state, i.e. __unwind_start own stack frame is taken or stack frame generated by __switch_to (ksp) - both known to be valid. In case of pt_regs %r15 is better match for pt_regs psw, than sometimes random "sp" caller passed. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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e76e6961 |
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22-Nov-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: stop gracefully at task pt_regs Consider reaching task pt_regs graceful unwinder termination. Task pt_regs itself never contains a valid state to which a task might return within the kernel context (user task pt_regs is a special case). Since we already avoid printing user task pt_regs and in most cases we don't even bother filling task pt_regs psw and r15 with something reasonable simply skip task pt_regs altogether. With this change unwind_error() now accurately represent whether unwinder reached task pt_regs successfully or failed along the way. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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97806dfb |
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22-Nov-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: make reuse_sp default when unwinding pt_regs Currently unwinder yields 2 entries when pt_regs are met: sp="address of pt_regs itself" ip=pt_regs->psw sp=pt_regs->gprs[15] ip="r14 from stack frame pointed by pt_regs->gprs[15]" And neither of those 2 states (combination of sp and ip) ever happened. reuse_sp has been introduced by commit a1d863ac3e10 ("s390/unwind: fix mixing regs and sp"). reuse_sp=true makes unwinder keen to produce the following result, when pt_regs are given (as an arg to unwind_start): sp=pt_regs->gprs[15] ip=pt_regs->psw sp=pt_regs->gprs[15] ip="r14 from stack frame pointed by pt_regs->gprs[15]" The first state is an actual state in which a task was when pt_regs were collected. The second state is marked unreliable and is for debugging purposes to cover the case when a task has been interrupted in between stack frame allocation and writing back_chain - in this case r14 might show an actual caller. Make unwinder behaviour enabled via reuse_sp=true default and drop the special case handling. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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67f55934 |
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22-Nov-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: report an error if pt_regs are not on stack If unwinder is looking at pt_regs which is not on stack then something went wrong and an error has to be reported rather than successful unwinding termination. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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c2f2093e |
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29-Oct-2019 |
Miroslav Benes <mbenes@suse.cz> |
s390/unwind: drop unnecessary code around calling ftrace_graph_ret_addr() The current code around calling ftrace_graph_ret_addr() is ifdeffed and also tests if ftrace redirection is present on stack. ftrace_graph_ret_addr() however performs the test internally and there is a version for !CONFIG_FUNCTION_GRAPH_TRACER as well. The unnecessary code can thus be dropped. Link: http://lkml.kernel.org/r/20191029143904.24051-2-mbenes@suse.cz Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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a1d863ac |
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02-Oct-2019 |
Ilya Leoshkevich <iii@linux.ibm.com> |
s390/unwind: fix mixing regs and sp unwind_for_each_frame stops after the first frame if regs->gprs[15] <= sp. The reason is that in case regs are specified, the first frame should be regs->psw.addr and the second frame should be sp->gprs[8]. However, currently the second frame is regs->gprs[15], which confuses outside_of_stack(). Fix by introducing a flag to distinguish this special case from unwinding the interrupt handler, for which the current behavior is appropriate. Fixes: 78c98f907413 ("s390/unwind: introduce stack unwind API") Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Cc: stable@vger.kernel.org # v5.2+ Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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9a159190 |
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08-Jul-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/unwind: avoid int overflow in outside_of_stack When current task is interrupted in-between stack frame allocation and backchain write instructions new stack frame backchain pointer is left uninitialized. That invalid backchain value is passed into outside_of_stack for sanity check. Make sure int overflow does not happen by subtracting stack_frame size from the stack "end" rather than adding it to "random" backchain value. Fixes: 41b0474c1b1c ("s390/unwind: introduce stack unwind API") Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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20955746 |
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20-Jun-2019 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/kasan: avoid false positives during stack unwind Avoid kasan false positive when current task is interrupted in-between stack frame allocation and backchain write instructions leaving new stack frame backchain invalid. In particular if backchain is 0 the unwinder tries to read pt_regs from the stack and might hit kasan poisoned bytes, leading to kasan "stack-out-of-bounds" report. Disable kasan instrumentation of unwinder stack reads, since this limitation couldn't be handled otherwise with current backchain unwinder implementation. Fixes: 78c98f907413 ("s390/unwind: introduce stack unwind API") Reported-by: Julian Wiedmann <jwi@linux.ibm.com> Tested-by: Benjamin Block <bblock@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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ec7bf478 |
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18-Feb-2019 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
s390/ftrace: use HAVE_FUNCTION_GRAPH_RET_ADDR_PTR Make the call chain more reliable by tagging the ftrace stack entries with the stack pointer that is associated with the return address. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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78c98f90 |
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28-Jan-2019 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
s390/unwind: introduce stack unwind API Rework the dump_trace() stack unwinder interface to support different unwinding algorithms. The new interface looks like this: struct unwind_state state; unwind_for_each_frame(&state, task, regs, start_stack) do_something(state.sp, state.ip, state.reliable); The unwind_bc.c file contains the implementation for the classic back-chain unwinder. One positive side effect of the new code is it now handles ftraced functions gracefully. It prints the real name of the return function instead of 'return_to_handler'. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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