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arm64: alternatives: have callbacks take a cap

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Today, callback alternatives are special-cased within
__apply_alternatives(), and are applied alongside patching for system
capabilities as ARM64_NCAPS is not part of the boot_capabilities feature
mask.

This special-casing is less than ideal. Giving special meaning to
ARM64_NCAPS for this requires some structures and loops to use
ARM64_NCAPS + 1 (AKA ARM64_NPATCHABLE), while others use ARM64_NCAPS.
It's also not immediately clear callback alternatives are only applied
when applying alternatives for system-wide features.

To make this a bit clearer, changes the way that callback alternatives
are identified to remove the special-casing of ARM64_NCAPS, and to allow
callback alternatives to be associated with a cpucap as with all other
alternatives.

New cpucaps, ARM64_ALWAYS_BOOT and ARM64_ALWAYS_SYSTEM are added which
are always detected alongside boot cpu capabilities and system
capabilities respectively. All existing callback alternatives are made
to use ARM64_ALWAYS_SYSTEM, and so will be patched at the same point
during the boot flow as before.

Subsequent patches will make more use of these new cpucaps.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220912162210.3626215-7-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland
2022-09-12 17:22:08 +01:00
committed by Catalin Marinas
parent b723edf3a1
commit 4c0bd995d7
9 changed files with 60 additions and 36 deletions
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10
arch/arm64/include/asm/assembler.h
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@@ -293,7 +293,7 @@ alternative_endif
alternative_if_not ARM64_KVM_PROTECTED_MODE
ASM_BUG()
alternative_else_nop_endif
alternative_cb kvm_compute_final_ctr_el0
alternative_cb ARM64_ALWAYS_SYSTEM, kvm_compute_final_ctr_el0
movz \reg, #0
movk \reg, #0, lsl #16
movk \reg, #0, lsl #32
@@ -877,7 +877,7 @@ alternative_endif
.macro __mitigate_spectre_bhb_loop tmp
#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
alternative_cb spectre_bhb_patch_loop_iter
alternative_cb ARM64_ALWAYS_SYSTEM, spectre_bhb_patch_loop_iter
mov \tmp, #32 // Patched to correct the immediate
alternative_cb_end
.Lspectre_bhb_loop\@:
@@ -890,7 +890,7 @@ alternative_cb_end
.macro mitigate_spectre_bhb_loop tmp
#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
alternative_cb spectre_bhb_patch_loop_mitigation_enable
alternative_cb ARM64_ALWAYS_SYSTEM, spectre_bhb_patch_loop_mitigation_enable
b .L_spectre_bhb_loop_done\@ // Patched to NOP
alternative_cb_end
__mitigate_spectre_bhb_loop \tmp
@@ -904,7 +904,7 @@ alternative_cb_end
stp x0, x1, [sp, #-16]!
stp x2, x3, [sp, #-16]!
mov w0, #ARM_SMCCC_ARCH_WORKAROUND_3
alternative_cb smccc_patch_fw_mitigation_conduit
alternative_cb ARM64_ALWAYS_SYSTEM, smccc_patch_fw_mitigation_conduit
nop // Patched to SMC/HVC #0
alternative_cb_end
ldp x2, x3, [sp], #16
@@ -914,7 +914,7 @@ alternative_cb_end
.macro mitigate_spectre_bhb_clear_insn
#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
alternative_cb spectre_bhb_patch_clearbhb
alternative_cb ARM64_ALWAYS_SYSTEM, spectre_bhb_patch_clearbhb
/* Patched to NOP when not supported */
clearbhb
isb