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powerpc/watchpoints: Disable preemption in thread_change_pc()
[ Upstream commitcc879ab3ce
] 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 after1e60f3564b
("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>
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parent
ee8bbb2a31
commit
16722418cb
1 changed files with 6 additions and 1 deletions
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@ -505,11 +505,13 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
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struct arch_hw_breakpoint *info;
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int i;
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preempt_disable();
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for (i = 0; i < nr_wp_slots(); i++) {
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if (unlikely(tsk->thread.last_hit_ubp[i]))
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goto reset;
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}
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return;
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goto out;
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reset:
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regs_set_return_msr(regs, regs->msr & ~MSR_SE);
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@ -518,6 +520,9 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
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__set_breakpoint(i, info);
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tsk->thread.last_hit_ubp[i] = NULL;
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}
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out:
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preempt_enable();
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}
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static bool is_larx_stcx_instr(int type)
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