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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2019-07-15 11:51:39 -0500 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-08-13 12:39:22 +0100 |
| commit | e191f5119eba311b3585492174825db763eeb3b9 (patch) | |
| tree | 97b609ba0a4b57e35568a83315bc46a38053ae2f | |
| parent | bba3308d5fe2c8c4605db3ea868ba57ad990d27d (diff) | |
| download | linux-stable-e191f5119eba311b3585492174825db763eeb3b9.tar.gz linux-stable-e191f5119eba311b3585492174825db763eeb3b9.tar.bz2 linux-stable-e191f5119eba311b3585492174825db763eeb3b9.zip | |
x86/entry/64: Use JMP instead of JMPQ
commit 64dbc122b20f75183d8822618c24f85144a5a94d upstream.
Somehow the swapgs mitigation entry code patch ended up with a JMPQ
instruction instead of JMP, where only the short jump is needed. Some
assembler versions apparently fail to optimize JMPQ into a two-byte JMP
when possible, instead always using a 7-byte JMP with relocation. For
some reason that makes the entry code explode with a #GP during boot.
Change it back to "JMP" as originally intended.
Fixes: 18ec54fdd6d1 ("x86/speculation: Prepare entry code for Spectre v1 swapgs mitigations")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index b4274d9a4e2e..467069f38f21 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -267,7 +267,7 @@ ENDPROC(native_usergs_sysret64) SWAPGS FENCE_SWAPGS_USER_ENTRY SWITCH_KERNEL_CR3 - jmpq 2f + jmp 2f 1: FENCE_SWAPGS_KERNEL_ENTRY 2: |