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| author | Benjamin Gray <bgray@linux.ibm.com> | 2023-08-29 16:34:55 +1000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-10-06 13:18:18 +0200 |
| commit | 7eb09f70d9c22940ecd2f0399f33c520e2976750 (patch) | |
| tree | 8bfd4611346466b9de7fe75877b8e254837eeb0d | |
| parent | 134b01a39077d96cd827f7139368be80c28ab1c5 (diff) | |
| download | linux-7eb09f70d9c22940ecd2f0399f33c520e2976750.tar.gz linux-7eb09f70d9c22940ecd2f0399f33c520e2976750.tar.bz2 linux-7eb09f70d9c22940ecd2f0399f33c520e2976750.zip | |
powerpc/watchpoints: Disable preemption in thread_change_pc()
[ Upstream commit cc879ab3ce39bc39f9b1d238b283f43a5f6f957d ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -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 91a3be14808b..63fec0602af2 100644 --- a/arch/powerpc/kernel/hw_breakpoint.c +++ b/arch/powerpc/kernel/hw_breakpoint.c @@ -478,11 +478,13 @@ 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++) { if (unlikely(tsk->thread.last_hit_ubp[i])) goto reset; } - return; + goto out; reset: regs_set_return_msr(regs, regs->msr & ~MSR_SE); @@ -491,6 +493,9 @@ reset: __set_breakpoint(i, info); tsk->thread.last_hit_ubp[i] = NULL; } + +out: + preempt_enable(); } static bool is_larx_stcx_instr(int type) |