powerpc/32: Statically initialise first emergency context

[ Upstream commit a4719f5bb6d7dc220bffdc1b9f5ce5eaa5543581 ]

The check of the emergency context initialisation in
vmap_stack_overflow is buggy for the SMP case, as it
compares r1 with 0 while in the SMP case r1 is offseted
by the CPU id.

Instead of fixing it, just perform static initialisation
of the first emergency context.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4a67ba422be75713286dca0c86ee0d3df2eb6dfa.1615552867.git.christophe.leroy@csgroup.eu
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index abc7b603ab65c3d0985211b22d675c411c5905f0..294dd0082ad2f974e2aa0e16126290edbfb2058b 100644 (file)
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -331,11 +331,7 @@ label:
        lis     r1, emergency_ctx@ha
 #endif
        lwz     r1, emergency_ctx@l(r1)
-       cmpwi   cr1, r1, 0
-       bne     cr1, 1f
-       lis     r1, init_thread_union@ha
-       addi    r1, r1, init_thread_union@l
-1:     addi    r1, r1, THREAD_SIZE - INT_FRAME_SIZE
+       addi    r1, r1, THREAD_SIZE - INT_FRAME_SIZE
        EXCEPTION_PROLOG_2
        SAVE_NVGPRS(r11)
        addi    r3, r1, STACK_FRAME_OVERHEAD

diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 8ba49a6bf5159e7ff57e8143728958cefbd93e5f..d7c1f92152af6720e26d3220d0a2f2c08cdc809f 100644 (file)
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -164,7 +164,7 @@ void __init irqstack_early_init(void)
 }
 
 #ifdef CONFIG_VMAP_STACK
-void *emergency_ctx[NR_CPUS] __ro_after_init;
+void *emergency_ctx[NR_CPUS] __ro_after_init = {[0] = &init_stack};
 
 void __init emergency_stack_init(void)
 {