4.9-stable review patch. If anyone has any objections, please let me know.
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From: Will Deacon will.deacon@arm.com
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 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: Alex Shi alex.shi@linaro.org [v4.9 backport] Signed-off-by: Mark Rutland mark.rutland@arm.com [v4.9 backport] Tested-by: Will Deacon will.deacon@arm.com Tested-by: Greg Hackmann ghackmann@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/entry.S | 39 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 3 deletions(-)
--- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -72,10 +72,26 @@
.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 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 @@ -157,18 +173,20 @@ ct_user_enter 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 msr spsr_el1, x22 @@ -189,7 +207,22 @@ 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 get_thread_info, rd