| Message ID | 20180304173025.19520-1-vaibhav@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | e1368d0c9edbc366e45216e7295fd61ae55c2b12 |
| Headers | show |
| Series | [v2] xmon: Setup xmon debugger hooks when first break-point is set | expand |
On Mon, Mar 5, 2018 at 4:30 AM, Vaibhav Jain <vaibhav@linux.vnet.ibm.com> wrote: > Presently sysrq key for xmon('x') is registered during kernel init > irrespective of the value of kernel param 'xmon'. Thus xmon is enabled > even if 'xmon=off' is passed on the kernel command line. However this > doesn't enable the kernel debugger hooks needed for instruction or data > breakpoints. Thus when a break-point is hit with xmon=off a kernel oops > of the form below is reported: > > Oops: Exception in kernel mode, sig: 5 [#1] > < snip > > Trace/breakpoint trap > > To fix this the patch checks and enables debugger hooks when an > instruction or data break-point is set via xmon console. > > Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com> > --- Reviewed-by: Balbir Singh <bsingharora@gmail.com>
On Sun, 2018-03-04 at 17:30:25 UTC, Vaibhav Jain wrote: > Presently sysrq key for xmon('x') is registered during kernel init > irrespective of the value of kernel param 'xmon'. Thus xmon is enabled > even if 'xmon=off' is passed on the kernel command line. However this > doesn't enable the kernel debugger hooks needed for instruction or data > breakpoints. Thus when a break-point is hit with xmon=off a kernel oops > of the form below is reported: > > Oops: Exception in kernel mode, sig: 5 [#1] > < snip > > Trace/breakpoint trap > > To fix this the patch checks and enables debugger hooks when an > instruction or data break-point is set via xmon console. > > Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com> > Reviewed-by: Balbir Singh <bsingharora@gmail.com> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/e1368d0c9edbc366e45216e7295fd6 cheers
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index 82e1a3ee6e0f..e9c7ec8f15f8 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -1273,6 +1273,18 @@ static long check_bp_loc(unsigned long addr) return 1; } +/* Force enable xmon if not already enabled */ +static inline void force_enable_xmon(void) +{ + static const char warnxmon[] = "xmon: Enabling debugger hooks\n"; + + /* Enable xmon hooks if needed */ + if (!xmon_on) { + printf(warnxmon); + xmon_on = 1; + } +} + static char *breakpoint_help_string = "Breakpoint command usage:\n" "b show breakpoints\n" @@ -1315,6 +1327,8 @@ bpt_cmds(void) dabr.address &= ~HW_BRK_TYPE_DABR; dabr.enabled = mode | BP_DABR; } + + force_enable_xmon(); break; case 'i': /* bi - hardware instr breakpoint */ @@ -1335,6 +1349,7 @@ bpt_cmds(void) if (bp != NULL) { bp->enabled |= BP_CIABR; iabr = bp; + force_enable_xmon(); } break; #endif @@ -1399,8 +1414,10 @@ bpt_cmds(void) if (!check_bp_loc(a)) break; bp = new_breakpoint(a); - if (bp != NULL) + if (bp != NULL) { bp->enabled |= BP_TRAP; + force_enable_xmon(); + } break; } }
Presently sysrq key for xmon('x') is registered during kernel init irrespective of the value of kernel param 'xmon'. Thus xmon is enabled even if 'xmon=off' is passed on the kernel command line. However this doesn't enable the kernel debugger hooks needed for instruction or data breakpoints. Thus when a break-point is hit with xmon=off a kernel oops of the form below is reported: Oops: Exception in kernel mode, sig: 5 [#1] < snip > Trace/breakpoint trap To fix this the patch checks and enables debugger hooks when an instruction or data break-point is set via xmon console. Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com> --- Change-log: v2 -> Moved the code that was force enabling xmon to a separate inline function (Balbir) The change related to clearing all breakpoints when xmon is disabled via debugfs will be respinned as a separate patch. (Mpe) --- arch/powerpc/xmon/xmon.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)