From 501c26e82df8d253851b80082778eeb37e4bab5c Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Fri, 15 Dec 2017 16:20:56 -0800 Subject: [PATCH] xtensa: implement early_trap_init Paging on xtensa architecture requires functioning exception handling because hardware cannot transparently access page tables that are not currently mapped by TLB. Exception handling is set up late in the initialization process, but working paging is needed for KASAN. Provide early_trap_init that sets up minimal exception handling sufficient for KASAN to work. Signed-off-by: Max Filippov --- arch/xtensa/include/asm/traps.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/xtensa/include/asm/traps.h b/arch/xtensa/include/asm/traps.h index 5bd19709..f5cd7a7 100644 --- a/arch/xtensa/include/asm/traps.h +++ b/arch/xtensa/include/asm/traps.h @@ -42,6 +42,18 @@ struct exc_table { */ extern void * __init trap_set_handler(int cause, void *handler); extern void do_unhandled(struct pt_regs *regs, unsigned long exccause); +void fast_second_level_miss(void); + +/* Initialize minimal exc_table structure sufficient for basic paging */ +static inline void __init early_trap_init(void) +{ + static struct exc_table exc_table __initdata = { + .fast_kernel_handler[EXCCAUSE_DTLB_MISS] = + fast_second_level_miss, + }; + __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (&exc_table)); +} + void secondary_trap_init(void); static inline void spill_registers(void) -- 2.7.4