diff options
| author | James Morse <james.morse@arm.com> | 2021-11-23 18:41:43 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-03-11 12:11:52 +0100 |
| commit | d93b25a6654812e0511b71a6d4a207f6b1ce5dfe (patch) | |
| tree | 47affccd8d1269e10627ac3500ca532a75e4124c | |
| parent | 5242d6971e106be115d9dace9c1441f4a2e1cb25 (diff) | |
arm64: entry: Free up another register on kpti's tramp_exit path
commit 03aff3a77a58b5b52a77e00537a42090ad57b80b upstream.
Kpti stashes x30 in far_el1 while it uses x30 for all its work.
Making the vectors a per-cpu data structure will require a second
register.
Allow tramp_exit two registers before it unmaps the kernel, by
leaving x30 on the stack, and stashing x29 in far_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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm64/kernel/entry.S | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 8b4b4d97b066..233c228921cd 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -357,14 +357,16 @@ alternative_else_nop_endif ldp x24, x25, [sp, #16 * 12] ldp x26, x27, [sp, #16 * 13] ldp x28, x29, [sp, #16 * 14] - ldr lr, [sp, #S_LR] - add sp, sp, #S_FRAME_SIZE // restore sp .if \el == 0 -alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 +alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 + ldr lr, [sp, #S_LR] + add sp, sp, #S_FRAME_SIZE // restore sp + eret +alternative_else_nop_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 bne 4f - msr far_el1, x30 + msr far_el1, x29 tramp_alias x30, tramp_exit_native br x30 4: @@ -372,6 +374,9 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 br x30 #endif .else + ldr lr, [sp, #S_LR] + add sp, sp, #S_FRAME_SIZE // restore sp + /* Ensure any device/NC reads complete */ alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 @@ -844,10 +849,12 @@ alternative_else_nop_endif .macro tramp_exit, regsize = 64 adr x30, tramp_vectors msr vbar_el1, x30 - tramp_unmap_kernel x30 + ldr lr, [sp, #S_LR] + tramp_unmap_kernel x29 .if \regsize == 64 - mrs x30, far_el1 + mrs x29, far_el1 .endif + add sp, sp, #S_FRAME_SIZE // restore sp eret sb .endm |