diff options
| author | Benjamin Gray <bgray@linux.ibm.com> | 2023-08-29 16:34:55 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-09-18 12:23:47 +1000 |
| commit | cc879ab3ce39bc39f9b1d238b283f43a5f6f957d (patch) | |
| tree | 8110700ed8845eb60e09ab728ebfecb578a18ac0 /arch/powerpc/kernel/hw_breakpoint.c | |
| parent | 4ff3ba4db5943cac1045e3e4a3c0463ea10f6930 (diff) | |
powerpc/watchpoints: Disable preemption in thread_change_pc()
thread_change_pc() uses CPU local data, so must be protected from
swapping CPUs while it is reading the breakpoint struct.
The error is more noticeable after 1e60f3564bad ("powerpc/watchpoints:
Track perf single step directly on the breakpoint"), which added an
unconditional __this_cpu_read() call in thread_change_pc(). However the
existing __this_cpu_read() that runs if a breakpoint does need to be
re-inserted has the same issue.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230829063457.54157-2-bgray@linux.ibm.com
Diffstat (limited to 'arch/powerpc/kernel/hw_breakpoint.c')
| -rw-r--r-- | arch/powerpc/kernel/hw_breakpoint.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c index b8513dc3e53a..2854376870cf 100644 --- a/arch/powerpc/kernel/hw_breakpoint.c +++ b/arch/powerpc/kernel/hw_breakpoint.c @@ -230,13 +230,15 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs) struct arch_hw_breakpoint *info; int i; + preempt_disable(); + for (i = 0; i < nr_wp_slots(); i++) { struct perf_event *bp = __this_cpu_read(bp_per_reg[i]); if (unlikely(bp && counter_arch_bp(bp)->perf_single_step)) goto reset; } - return; + goto out; reset: regs_set_return_msr(regs, regs->msr & ~MSR_SE); @@ -245,6 +247,9 @@ reset: __set_breakpoint(i, info); info->perf_single_step = false; } + +out: + preempt_enable(); } static bool is_larx_stcx_instr(int type) |