powerpc: Fix CONFIG_TRACE_IRQFLAGS with CONFIG_VMAP_STACK

When CONFIG_PROVE_LOCKING is selected together with (now default)
CONFIG_VMAP_STACK, kernel enter deadlock during boot.

At the point of checking whether interrupts are enabled or not, the
value of MSR saved on stack is read using the physical address of the
stack. But at this point, when using VMAP stack the DATA MMU
translation has already been re-enabled, leading to deadlock.

Don't use the physical address of the stack when
CONFIG_VMAP_STACK is set.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 028474876f47 ("powerpc/32: prepare for CONFIG_VMAP_STACK")
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/daeacdc0dec0416d1c587cc9f9e7191ad3068dc0.1581095957.git.christophe.leroy@c-s.fr

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 77abbc3..0713daa 100644 (file)
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -214,7 +214,7 @@ transfer_to_handler_cont:
         * To speed up the syscall path where interrupts stay on, let's check
         * first if we are changing the MSR value at all.
         */
-       tophys(r12, r1)
+       tophys_novmstack r12, r1
        lwz     r12,_MSR(r12)
        andi.   r12,r12,MSR_EE
        bne     1f