From 6472f1a3a54f061864a5091788778793661aa7c0 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 14 Nov 2017 14:24:29 +0000 Subject: [PATCH] arm64: entry: Hook up entry trampoline to exception vectors Commit 4bf3286d29f3 upstream. 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 Tested-by: Laura Abbott Tested-by: Shanker Donthineni Signed-off-by: Will Deacon Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman --- 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 fa924eb6b4c2..f66ab8eb45b9 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -73,6 +73,17 @@ .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 /* @@ -119,6 +130,11 @@ 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 @@ -269,18 +285,20 @@ 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 @@ -302,7 +320,22 @@ 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 -- 2.20.1