x86/entry/64: Stop initializing TSS.sp0 at boot

[linux.git] / arch / x86 / kernel / process.c

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index bd6b85fac66696da70e316656ad6f0d51291f8aa..ff8a9acbcf8bddc4eba6b18193ed622e5a01ef04 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -48,7 +48,13 @@
  */
 __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
        .x86_tss = {
-               .sp0 = TOP_OF_INIT_STACK,
+               /*
+                * .sp0 is only used when entering ring 0 from a lower
+                * privilege level.  Since the init task never runs anything
+                * but ring 0 code, there is no need for a valid value here.
+                * Poison it.
+                */
+               .sp0 = (1UL << (BITS_PER_LONG-1)) + 1,
 #ifdef CONFIG_X86_32
                .ss0 = __KERNEL_DS,
                .ss1 = __KERNEL_CS,