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authorGravatar Ravi Bangoria <ravi.bangoria@linux.ibm.com> 2020-09-02 09:59:42 +0530
committerGravatar Michael Ellerman <mpe@ellerman.id.au> 2020-09-15 22:13:20 +1000
commit5b905d77987de065bdd3a2906816b5f143df087b (patch)
tree0c35d7c18b1d8902425b792d1102835ca582af13 /block
parentpowerpc/watchpoint: Move DAWR detection logic outside of hw_breakpoint.c (diff)
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powerpc/watchpoint: Fix exception handling for CONFIG_HAVE_HW_BREAKPOINT=N
On powerpc, ptrace watchpoint works in one-shot mode. i.e. kernel disables event every time it fires and user has to re-enable it. Also, in case of ptrace watchpoint, kernel notifies ptrace user before executing instruction. With CONFIG_HAVE_HW_BREAKPOINT=N, kernel is missing to disable ptrace event and thus it's causing infinite loop of exceptions. This is especially harmful when user watches on a data which is also read/written by kernel, eg syscall parameters. In such case, infinite exceptions happens in kernel mode which causes soft-lockup. Fixes: 9422de3e953d ("powerpc: Hardware breakpoints rewrite to handle non DABR breakpoint registers") Reported-by: Pedro Miraglia Franco de Carvalho <pedromfc@linux.ibm.com> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200902042945.129369-6-ravi.bangoria@linux.ibm.com
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