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| author | Mark Rutland <mark.rutland@arm.com> | 2024-01-16 11:02:21 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2024-01-18 11:00:09 +0000 |
| commit | da59f1d051d57e85eca49401a3a36d5a622babde (patch) | |
| tree | d937594d6f27b2ab49e62c98dd6560aa9d1ca517 /arch/arm64 | |
| parent | 832dd634bd1b4e3bbe9f10b9c9ba5db6f6f2b97f (diff) | |
| download | linux-da59f1d051d57e85eca49401a3a36d5a622babde.tar.gz linux-da59f1d051d57e85eca49401a3a36d5a622babde.tar.bz2 linux-da59f1d051d57e85eca49401a3a36d5a622babde.zip | |
arm64: entry: simplify kernel_exit logic
For historical reasons, the non-KPTI exception return path is duplicated for
EL1 and EL0, with the structure:
.if \el == 0
[ KPTI handling ]
ldr lr, [sp, #S_LR]
add sp, sp, #PT_REGS_SIZE // restore sp
[ EL0 exception return workaround ]
eret
.else
ldr lr, [sp, #S_LR]
add sp, sp, #PT_REGS_SIZE // restore sp
[ EL1 exception return workaround ]
eret
.endif
sb
This would be simpler and clearer with the common portions factored out,
e.g.
.if \el == 0
[ KPTI handling ]
.endif
ldr lr, [sp, #S_LR]
add sp, sp, #PT_REGS_SIZE // restore sp
.if \el == 0
[ EL0 exception return workaround ]
.else
[ EL1 exception return workaround ]
.endif
eret
sb
This expands to the same code, but is simpler for a human to follow as
it avoids duplicates the restore of LR+SP, and makes it clear that the
ERET is associated with the SB.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20240116110221.420467-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 7fcbee0f6c0e..7ef0e127b149 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -442,24 +442,23 @@ alternative_else_nop_endif .L_skip_tramp_exit_\@: #endif + .endif + ldr lr, [sp, #S_LR] add sp, sp, #PT_REGS_SIZE // restore sp + .if \el == 0 /* This must be after the last explicit memory access */ alternative_if ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD tlbi vale1, xzr dsb nsh alternative_else_nop_endif - eret .else - ldr lr, [sp, #S_LR] - add sp, sp, #PT_REGS_SIZE // restore sp - /* Ensure any device/NC reads complete */ alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 + .endif eret - .endif sb .endm |