Commit 4fb5f58e authored by Zhenzhong Duan's avatar Zhenzhong Duan Committed by Ingo Molnar

x86/mm/32: Initialize the CR4 shadow before __flush_tlb_all()

On 32-bit kernels, __flush_tlb_all() may have read the CR4 shadow before the
initialization of CR4 shadow in cpu_init().

Fix it by adding an explicit cr4_init_shadow() call into start_secondary()
which is the first function called on non-boot SMP CPUs - ahead of the
__flush_tlb_all() call.

( This is somewhat of a layering violation, but start_secondary() does
  CR4 bootstrap in the PCID case anyway. )
Signed-off-by: default avatarZhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/r/b07b6ae9-4b57-4b40-b9bc-50c2c67f1d91@defaultSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 021c9179
...@@ -221,6 +221,11 @@ static void notrace start_secondary(void *unused) ...@@ -221,6 +221,11 @@ static void notrace start_secondary(void *unused)
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32
/* switch away from the initial page table */ /* switch away from the initial page table */
load_cr3(swapper_pg_dir); load_cr3(swapper_pg_dir);
/*
* Initialize the CR4 shadow before doing anything that could
* try to read it.
*/
cr4_init_shadow();
__flush_tlb_all(); __flush_tlb_all();
#endif #endif
load_current_idt(); load_current_idt();
......
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