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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-01-17 22:54:56 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-01-17 22:54:56 +0300 |
| commit | 88dc7fca18001fd883e5ace775afa316b68c8f2c (patch) | |
| tree | 224bd71272b4cbc268ced27d9b3160fabb5755d8 /arch/x86/entry/entry_64.S | |
| parent | dd43f3465d138439db451a5e7ddccefc5af2fa85 (diff) | |
| parent | 6cfb521ac0d5b97470883ff9b7facae264b7ab12 (diff) | |
| download | linux-88dc7fca18001fd883e5ace775afa316b68c8f2c.tar.xz | |
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 pti bits and fixes from Thomas Gleixner:
"This last update contains:
- An objtool fix to prevent a segfault with the gold linker by
changing the invocation order. That's not just for gold, it's a
general robustness improvement.
- An improved error message for objtool which spares tearing hairs.
- Make KASAN fail loudly if there is not enough memory instead of
oopsing at some random place later
- RSB fill on context switch to prevent RSB underflow and speculation
through other units.
- Make the retpoline/RSB functionality work reliably for both Intel
and AMD
- Add retpoline to the module version magic so mismatch can be
detected
- A small (non-fix) update for cpufeatures which prevents cpu feature
clashing for the upcoming extra mitigation bits to ease
backporting"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
module: Add retpoline tag to VERMAGIC
x86/cpufeature: Move processor tracing out of scattered features
objtool: Improve error message for bad file argument
objtool: Fix seg fault with gold linker
x86/retpoline: Add LFENCE to the retpoline/RSB filling RSB macros
x86/retpoline: Fill RSB on context switch for affected CPUs
x86/kasan: Panic if there is not enough memory to boot
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 4f8e1d35a97c..aa15b4c0e3d1 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -491,6 +491,17 @@ ENTRY(__switch_to_asm) movq %rbx, PER_CPU_VAR(irq_stack_union)+stack_canary_offset #endif +#ifdef CONFIG_RETPOLINE + /* + * When switching from a shallower to a deeper call stack + * the RSB may either underflow or use entries populated + * with userspace addresses. On CPUs where those concerns + * exist, overwrite the RSB with entries which capture + * speculative execution to prevent attack. + */ + FILL_RETURN_BUFFER %r12, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW +#endif + /* restore callee-saved registers */ popq %r15 popq %r14 |