| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.17 172/324] x86/mm/32: Initialize the CR4 shadow before __flush_tlb_all() | Date | Thu, 23 Aug 2018 09:53:58 +0200 |
| |
4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhenzhong Duan <zhenzhong.duan@oracle.com>
[ Upstream commit 4fb5f58e8d191f7c81637ad81284e4848afb4244 ]
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: Zhenzhong 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@default Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/x86/kernel/smpboot.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -222,6 +222,11 @@ static void notrace start_secondary(void #ifdef CONFIG_X86_32 /* switch away from the initial page table */ load_cr3(swapper_pg_dir); + /* + * Initialize the CR4 shadow before doing anything that could + * try to read it. + */ + cr4_init_shadow(); __flush_tlb_all(); #endif load_current_idt();
|