powerpc/64/kuap: Move kuap checks out of MSR[RI]=0 regions of exit code

Any kind of WARN causes a program check that will crash with
unrecoverable exception if it occurs when RI is clear.

Fixes: 68b34588e202 ("powerpc/64/sycall: Implement syscall entry/exit logic in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200429065654.1677541-2-npiggin@gmail.com

diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
index 1fe94dd9de3283f43dc040b73d50741b2719503c..7b7c89cad901b8e2455dfc3f751931c8b8265dcb 100644 (file)
--- a/arch/powerpc/kernel/syscall_64.c
+++ b/arch/powerpc/kernel/syscall_64.c
@@ -35,6 +35,8 @@ notrace long system_call_exception(long r3, long r4, long r5,
        BUG_ON(!FULL_REGS(regs));
        BUG_ON(regs->softe != IRQS_ENABLED);
 
+       kuap_check_amr();
+
        account_cpu_user_entry();
 
 #ifdef CONFIG_PPC_SPLPAR
@@ -47,8 +49,6 @@ notrace long system_call_exception(long r3, long r4, long r5,
        }
 #endif
 
-       kuap_check_amr();
-
        /*
         * This is not required for the syscall exit path, but makes the
         * stack frame look nicer. If this was initialised in the first stack
@@ -117,6 +117,8 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
        unsigned long ti_flags;
        unsigned long ret = 0;
 
+       kuap_check_amr();
+
        regs->result = r3;
 
        /* Check whether the syscall is issued inside a restartable sequence */
@@ -204,8 +206,6 @@ again:
        local_paca->tm_scratch = regs->msr;
 #endif
 
-       kuap_check_amr();
-
        account_cpu_user_exit();
 
        return ret;
@@ -228,6 +228,8 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
        BUG_ON(!FULL_REGS(regs));
        BUG_ON(regs->softe != IRQS_ENABLED);
 
+       kuap_check_amr();
+
        local_irq_save(flags);
 
 again:
@@ -292,8 +294,6 @@ again:
        local_paca->tm_scratch = regs->msr;
 #endif
 
-       kuap_check_amr();
-
        account_cpu_user_exit();
 
        return ret;
@@ -313,6 +313,8 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
        BUG_ON(regs->msr & MSR_PR);
        BUG_ON(!FULL_REGS(regs));
 
+       kuap_check_amr();
+
        if (unlikely(*ti_flagsp & _TIF_EMULATE_STACK_STORE)) {
                clear_bits(_TIF_EMULATE_STACK_STORE, ti_flagsp);
                ret = 1;