diff options
| author | Jan Kiszka <[email protected]> | 2018-10-15 16:09:29 +0200 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2018-10-17 12:30:20 +0200 |
| commit | 04f4f954b69526d7af8ffb8e5780f08b8a6cda2d (patch) | |
| tree | 2a3f3fc150400381d8e65bc958d42066cf155706 | |
| parent | dca5203e3fe2f5d8bc8157b205d766142d3a6b77 (diff) | |
x86/entry/32: Clear the CS high bits
Even if not on an entry stack, the CS's high bits must be
initialized because they are unconditionally evaluated in
PARANOID_EXIT_TO_KERNEL_MODE.
Failing to do so broke the boot on Galileo Gen2 and IOT2000 boards.
[ bp: Make the commit message tone passive and impartial. ]
Fixes: b92a165df17e ("x86/entry/32: Handle Entry from Kernel-Mode on Entry-Stack")
Signed-off-by: Jan Kiszka <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Joerg Roedel <[email protected]>
Acked-by: Joerg Roedel <[email protected]>
CC: "H. Peter Anvin" <[email protected]>
CC: Andrea Arcangeli <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Boris Ostrovsky <[email protected]>
CC: Brian Gerst <[email protected]>
CC: Dave Hansen <[email protected]>
CC: David Laight <[email protected]>
CC: Denys Vlasenko <[email protected]>
CC: Eduardo Valentin <[email protected]>
CC: Greg KH <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Jiri Kosina <[email protected]>
CC: Josh Poimboeuf <[email protected]>
CC: Juergen Gross <[email protected]>
CC: Linus Torvalds <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: Thomas Gleixner <[email protected]>
CC: Will Deacon <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: linux-mm <[email protected]>
CC: x86-ml <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/entry/entry_32.S | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 2767c625a52c..fbbf1ba57ec6 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -389,6 +389,13 @@ * that register for the time this macro runs */ + /* + * The high bits of the CS dword (__csh) are used for + * CS_FROM_ENTRY_STACK and CS_FROM_USER_CR3. Clear them in case + * hardware didn't do this for us. + */ + andl $(0x0000ffff), PT_CS(%esp) + /* Are we on the entry stack? Bail out if not! */ movl PER_CPU_VAR(cpu_entry_area), %ecx addl $CPU_ENTRY_AREA_entry_stack + SIZEOF_entry_stack, %ecx @@ -407,12 +414,6 @@ /* Load top of task-stack into %edi */ movl TSS_entry2task_stack(%edi), %edi - /* - * Clear unused upper bits of the dword containing the word-sized CS - * slot in pt_regs in case hardware didn't clear it for us. - */ - andl $(0x0000ffff), PT_CS(%esp) - /* Special case - entry from kernel mode via entry stack */ #ifdef CONFIG_VM86 movl PT_EFLAGS(%esp), %ecx # mix EFLAGS and CS |