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@xxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: James Morse <james.morse@xxxxxxx> Cc: Rob Herring <robh@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> --- arch/arm64/kernel/entry.S | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 7fcbee0f6c0e4..7ef0e127b149f 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 -- 2.30.2
