From fe314293b5b8a7f6d1e93290a96a3ce051ac8afd Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Tue, 14 Nov 2017 14:24:29 +0000
Subject: [PATCH 45/51] arm64: entry: Hook up entry trampoline to exception
vectors
Git-commit: 4bf3286d29f3a88425d8d8cd53428cbb8f865f04
Patch-mainline: v4.16-rc1
References: bsc#1068032
Hook up the entry trampoline to our exception vectors so that all
exceptions from and returns to EL0 go via the trampoline, which swizzles
the vector base register accordingly. Transitioning to and from the
kernel clobbers x30, so we use tpidrro_el0 and far_el1 as scratch
registers for native tasks.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
arch/arm64/kernel/entry.S | 39 ++++++++++++++++++++++++++++++++++++---
1 file changed, 36 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 276a847f5aa7..c17673415d00 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -72,6 +72,17 @@
.macro kernel_ventry, el, label, regsize = 64
.align 7
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+ .if \el == 0
+ .if \regsize == 64
+ mrs x30, tpidrro_el0
+ msr tpidrro_el0, xzr
+ .else
+ mov x30, xzr
+ .endif
+ .endif
+#endif
+
sub sp, sp, #S_FRAME_SIZE
#ifdef CONFIG_VMAP_STACK
/*
@@ -118,6 +129,11 @@
b el\()\el\()_\label
.endm
+ .macro tramp_alias, dst, sym
+ mov_q \dst, TRAMP_VALIAS
+ add \dst, \dst, #(\sym - .entry.tramp.text)
+ .endm
+
.macro kernel_entry, el, regsize = 64
.if \regsize == 32
mov w0, w0 // zero upper 32 bits of x0
@@ -272,18 +288,20 @@ alternative_else_nop_endif
.if \el == 0
ldr x23, [sp, #S_SP] // load return stack pointer
msr sp_el0, x23
+ tst x22, #PSR_MODE32_BIT // native task?
+ b.eq 3f
+
#ifdef CONFIG_ARM64_ERRATUM_845719
alternative_if ARM64_WORKAROUND_845719
- tbz x22, #4, 1f
#ifdef CONFIG_PID_IN_CONTEXTIDR
mrs x29, contextidr_el1
msr contextidr_el1, x29
#else
msr contextidr_el1, xzr
#endif
-1:
alternative_else_nop_endif
#endif
+3:
.endif
msr elr_el1, x21 // set up the return data
@@ -305,7 +323,22 @@ alternative_else_nop_endif
ldp x28, x29, [sp, #16 * 14]
ldr lr, [sp, #S_LR]
add sp, sp, #S_FRAME_SIZE // restore sp
- eret // return to kernel
+
+#ifndef CONFIG_UNMAP_KERNEL_AT_EL0
+ eret
+#else
+ .if \el == 0
+ bne 4f
+ msr far_el1, x30
+ tramp_alias x30, tramp_exit_native
+ br x30
+4:
+ tramp_alias x30, tramp_exit_compat
+ br x30
+ .else
+ eret
+ .endif
+#endif
.endm
.macro irq_stack_entry
--
2.11.0