x86/debug: Simplify hw_breakpoint_handler()

This is called with interrupts disabled, there's no point in using
get_cpu() and per_cpu().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.292906672@infradead.org

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index ca9de59ffb87e62bf248da789d8d91097857064f..7b7d9f23a9ad8b0f921521638e68eea09c3033d5 100644 (file)
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -487,7 +487,7 @@ EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
  */
 static int hw_breakpoint_handler(struct die_args *args)
 {
-       int i, cpu, rc = NOTIFY_STOP;
+       int i, rc = NOTIFY_STOP;
        struct perf_event *bp;
        unsigned long dr6;
        unsigned long *dr6_p;
@@ -505,12 +505,10 @@ static int hw_breakpoint_handler(struct die_args *args)
                return NOTIFY_DONE;
 
        /*
-        * Assert that local interrupts are disabled
         * Reset the DRn bits in the virtualized register value.
         * The ptrace trigger routine will add in whatever is needed.
         */
        current->thread.debugreg6 &= ~DR_TRAP_BITS;
-       cpu = get_cpu();
 
        /* Handle all the breakpoints that were triggered */
        for (i = 0; i < HBP_NUM; ++i) {
@@ -525,7 +523,7 @@ static int hw_breakpoint_handler(struct die_args *args)
                 */
                rcu_read_lock();
 
-               bp = per_cpu(bp_per_reg[i], cpu);
+               bp = this_cpu_read(bp_per_reg[i]);
                /*
                 * Reset the 'i'th TRAP bit in dr6 to denote completion of
                 * exception handling
@@ -560,8 +558,6 @@ static int hw_breakpoint_handler(struct die_args *args)
            (dr6 & (~DR_TRAP_BITS)))
                rc = NOTIFY_DONE;
 
-       put_cpu();
-
        return rc;
 }