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| author | James Morse <james.morse@arm.com> | 2021-12-10 15:32:56 +0100 |
|---|---|---|
| committer | James Morse <james.morse@arm.com> | 2022-02-24 15:02:44 +0100 |
| commit | 228a26b912287934789023b4132ba76065d9491c (patch) | |
| tree | 67a41ff4b1f85a9f72239a7f213d1ff2279af0ac /arch/arm64/kernel/entry.S | |
| parent | KVM: arm64: Allow SMCCC_ARCH_WORKAROUND_3 to be discovered and migrated (diff) | |
| download | linux-228a26b912287934789023b4132ba76065d9491c.tar.xz linux-228a26b912287934789023b4132ba76065d9491c.zip | |
arm64: Use the clearbhb instruction in mitigations
Future CPUs may implement a clearbhb instruction that is sufficient
to mitigate SpectreBHB. CPUs that implement this instruction, but
not CSV2.3 must be affected by Spectre-BHB.
Add support to use this instruction as the BHB mitigation on CPUs
that support it. The instruction is in the hint space, so it will
be treated by a NOP as older CPUs.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index a62fee121138..4a3a653df07e 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -657,6 +657,7 @@ alternative_else_nop_endif #define BHB_MITIGATION_NONE 0 #define BHB_MITIGATION_LOOP 1 #define BHB_MITIGATION_FW 2 +#define BHB_MITIGATION_INSN 3 .macro tramp_ventry, vector_start, regsize, kpti, bhb .align 7 @@ -673,6 +674,11 @@ alternative_else_nop_endif __mitigate_spectre_bhb_loop x30 .endif // \bhb == BHB_MITIGATION_LOOP + .if \bhb == BHB_MITIGATION_INSN + clearbhb + isb + .endif // \bhb == BHB_MITIGATION_INSN + .if \kpti == 1 /* * Defend against branch aliasing attacks by pushing a dummy @@ -749,6 +755,7 @@ SYM_CODE_START_NOALIGN(tramp_vectors) #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_LOOP generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_FW + generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_INSN #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_NONE SYM_CODE_END(tramp_vectors) @@ -811,6 +818,7 @@ SYM_CODE_START(__bp_harden_el1_vectors) #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY generate_el1_vector bhb=BHB_MITIGATION_LOOP generate_el1_vector bhb=BHB_MITIGATION_FW + generate_el1_vector bhb=BHB_MITIGATION_INSN #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ SYM_CODE_END(__bp_harden_el1_vectors) .popsection |