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Subject[PATCH v8 00/12] Retpoline: Avoid speculative indirect calls in kernel
Date
This is a mitigation for the 'variant 2' attack described in
https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html

Using GCC patches available from the hjl/indirect/gcc-7-branch/master
branch of https://github.com/hjl-tools/gcc/commits/hjl and by manually
patching assembler code, all vulnerable indirect branches (that occur
after userspace first runs) are eliminated from the kernel.

They are replaced with a 'retpoline' call sequence which deliberately
prevents speculation.

Fedora 27 packages of the updated compiler are available at
https://koji.fedoraproject.org/koji/taskinfo?taskID=24065739


v1: Initial post.
v2: Add CONFIG_RETPOLINE to build kernel without it.
Change warning messages.
Hide modpost warning message
v3: Update to the latest CET-capable retpoline version
Reinstate ALTERNATIVE support
v4: Finish reconciling Andi's and my patch sets, bug fixes.
Exclude objtool support for now
Add 'noretpoline' boot option
Add AMD retpoline alternative
v5: Silence MODVERSIONS warnings
Use pause;jmp loop instead of lfence;jmp
Switch to X86_FEATURE_RETPOLINE positive feature logic
Emit thunks inline from assembler macros
Merge AMD support into initial patch
v6: Update to latest GCC patches with no dots in symbols
Fix MODVERSIONS properly(ish)
Fix typo breaking 32-bit, introduced in V5
Never set X86_FEATURE_RETPOLINE_AMD yet, pending confirmation
v7: Further bikeshedding on macro names
Stuff RSB on kernel entry
Implement 'spectre_v2=' command line option for IBRS/IBPB too
Revert to precisely the asm sequences from the Google paper
v8: Re-enable (I won't say "fix") objtool support
Use numeric labels for GCC compatibility
Add support for RSB-stuffing on vmexit
I don't know... other bloody bikeshedding. Can I sleep now?

Andi Kleen (1):
x86/retpoline/irq32: Convert assembler indirect jumps

David Woodhouse (10):
objtool: Allow alternatives to be ignored
x86/retpoline: Add initial retpoline support
x86/spectre: Add boot time option to select Spectre v2 mitigation
x86/retpoline/crypto: Convert crypto assembler indirect jumps
x86/retpoline/entry: Convert entry assembler indirect jumps
x86/retpoline/ftrace: Convert ftrace assembler indirect jumps
x86/retpoline/hyperv: Convert assembler indirect jumps
x86/retpoline/xen: Convert Xen hypercall indirect jumps
x86/retpoline/checksum32: Convert assembler indirect jumps
x86/retpoline: Fill return stack buffer on vmexit

Josh Poimboeuf (1):
objtool: Detect jumps to retpoline thunks

Documentation/admin-guide/kernel-parameters.txt | 28 ++++
arch/x86/Kconfig | 13 ++
arch/x86/Makefile | 10 ++
arch/x86/crypto/aesni-intel_asm.S | 5 +-
arch/x86/crypto/camellia-aesni-avx-asm_64.S | 3 +-
arch/x86/crypto/camellia-aesni-avx2-asm_64.S | 3 +-
arch/x86/crypto/crc32c-pcl-intel-asm_64.S | 3 +-
arch/x86/entry/entry_32.S | 5 +-
arch/x86/entry/entry_64.S | 12 +-
arch/x86/include/asm/asm-prototypes.h | 25 +++
arch/x86/include/asm/cpufeatures.h | 2 +
arch/x86/include/asm/mshyperv.h | 18 +-
arch/x86/include/asm/nospec-branch.h | 209 ++++++++++++++++++++++++
arch/x86/include/asm/xen/hypercall.h | 5 +-
arch/x86/kernel/cpu/bugs.c | 158 +++++++++++++++++-
arch/x86/kernel/ftrace_32.S | 6 +-
arch/x86/kernel/ftrace_64.S | 8 +-
arch/x86/kernel/irq_32.c | 9 +-
arch/x86/kvm/svm.c | 4 +
arch/x86/kvm/vmx.c | 4 +
arch/x86/lib/Makefile | 1 +
arch/x86/lib/checksum_32.S | 7 +-
arch/x86/lib/retpoline.S | 48 ++++++
tools/objtool/check.c | 69 +++++++-
tools/objtool/check.h | 2 +-
25 files changed, 616 insertions(+), 41 deletions(-)
create mode 100644 arch/x86/include/asm/nospec-branch.h
create mode 100644 arch/x86/lib/retpoline.S

--
2.7.4

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