diff options
| author | Ravi Bangoria <ravi.bangoria@linux.ibm.com> | 2020-09-02 09:59:42 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-09-15 22:13:20 +1000 |
| commit | 5b905d77987de065bdd3a2906816b5f143df087b (patch) | |
| tree | 0c35d7c18b1d8902425b792d1102835ca582af13 /arch/powerpc/include/asm/hw_breakpoint.h | |
| parent | edc8dd99b29e4d705c45e2a3a6c01b096ee056db (diff) | |
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
Diffstat (limited to 'arch/powerpc/include/asm/hw_breakpoint.h')
| -rw-r--r-- | arch/powerpc/include/asm/hw_breakpoint.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h index 81872c420476..abebfbee5b1c 100644 --- a/arch/powerpc/include/asm/hw_breakpoint.h +++ b/arch/powerpc/include/asm/hw_breakpoint.h @@ -18,6 +18,7 @@ struct arch_hw_breakpoint { u16 type; u16 len; /* length of the target data symbol */ u16 hw_len; /* length programmed in hw */ + u8 flags; }; /* Note: Don't change the first 6 bits below as they are in the same order @@ -37,6 +38,8 @@ struct arch_hw_breakpoint { #define HW_BRK_TYPE_PRIV_ALL (HW_BRK_TYPE_USER | HW_BRK_TYPE_KERNEL | \ HW_BRK_TYPE_HYP) +#define HW_BRK_FLAG_DISABLED 0x1 + /* Minimum granularity */ #ifdef CONFIG_PPC_8xx #define HW_BREAKPOINT_SIZE 0x4 |