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arm64: entry: Add non-kpti __bp_harden_el1_vectors for mitigations

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kpti is an optional feature, for systems not using kpti a set of
vectors for the spectre-bhb mitigations is needed.

Add another set of vectors, __bp_harden_el1_vectors, that will be
used if a mitigation is needed and kpti is not in use.

The EL1 ventries are repeated verbatim as there is no additional
work needed for entry from EL1.

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>
This commit is contained in:
James Morse 2021-11-24 15:03:15 +00:00
parent a9c406e646
commit aff65393fa
1 changed files with 34 additions and 1 deletions
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35
arch/arm64/kernel/entry.S
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@ -649,10 +649,11 @@ alternative_else_nop_endif
.macro tramp_ventry, vector_start, regsize, kpti
.align 7
1:
.if \kpti == 1
.if \regsize == 64
msr tpidrro_el0, x30 // Restored in kernel_ventry
.endif
.if \kpti == 1
/*
* Defend against branch aliasing attacks by pushing a dummy
* entry onto the return stack and using a RET instruction to
@ -739,6 +740,38 @@ SYM_DATA_END(__entry_tramp_data_start)
#endif /* CONFIG_RANDOMIZE_BASE */
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
/*
* Exception vectors for spectre mitigations on entry from EL1 when
* kpti is not in use.
*/
.macro generate_el1_vector
.Lvector_start\@:
kernel_ventry 1, t, 64, sync // Synchronous EL1t
kernel_ventry 1, t, 64, irq // IRQ EL1t
kernel_ventry 1, t, 64, fiq // FIQ EL1h
kernel_ventry 1, t, 64, error // Error EL1t
kernel_ventry 1, h, 64, sync // Synchronous EL1h
kernel_ventry 1, h, 64, irq // IRQ EL1h
kernel_ventry 1, h, 64, fiq // FIQ EL1h
kernel_ventry 1, h, 64, error // Error EL1h
.rept 4
tramp_ventry .Lvector_start\@, 64, kpti=0
.endr
.rept 4
tramp_ventry .Lvector_start\@, 32, kpti=0
.endr
.endm
.pushsection ".entry.text", "ax"
.align 11
SYM_CODE_START(__bp_harden_el1_vectors)
generate_el1_vector
SYM_CODE_END(__bp_harden_el1_vectors)
.popsection
/*
* Register switch for AArch64. The callee-saved registers need to be saved
* and restored. On entry: