From: James Morse <james.morse@xxxxxxx> Today the 'hvc' calling kvm or the hyp-stub is expected to preserve all registers. Kvm saves/restores the registers it needs on the EL2 stack using do_el2_call. The hyp-stub has no stack, later patches need at least one register they can use. Allow theses calls to clobber the link register, and add code to save/restore this register at the call sites. Signed-off-by: James Morse <james.morse at arm.com> --- arch/arm64/include/asm/virt.h | 4 ---- arch/arm64/kernel/hyp-stub.S | 10 ++++++++-- arch/arm64/kvm/hyp.S | 7 ++++++- arch/arm64/kvm/hyp/hyp-entry.S | 2 ++ 4 files changed, 16 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index b8fddde..23e9c6f 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -27,15 +27,11 @@ * Shuffle the parameters before calling the function * pointed to in x0. Assumes parameters in x[1,2,3]. */ - sub sp, sp, #16 - str lr, [sp] mov lr, x0 mov x0, x1 mov x1, x2 mov x2, x3 blr lr - ldr lr, [sp] - add sp, sp, #16 .endm #else diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S index a272f33..7eab8ac 100644 --- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S @@ -101,10 +101,16 @@ ENDPROC(\label) */ ENTRY(__hyp_get_vectors) + str lr, [sp, #-16]! mov x0, xzr - // fall through -ENTRY(__hyp_set_vectors) hvc #0 + ldr lr, [sp], #16 ret ENDPROC(__hyp_get_vectors) + +ENTRY(__hyp_set_vectors) + str lr, [sp, #-16]! + hvc #0 + ldr lr, [sp], #16 + ret ENDPROC(__hyp_set_vectors) diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S index 48f19a3..4ee5612 100644 --- a/arch/arm64/kvm/hyp.S +++ b/arch/arm64/kvm/hyp.S @@ -38,13 +38,18 @@ * A function pointer with a value of 0 has a special meaning, and is * used to implement __hyp_get_vectors in the same way as in * arch/arm64/kernel/hyp_stub.S. + * HVC behaves as a 'bl' call and will clobber lr. */ ENTRY(__kvm_call_hyp) -alternative_if_not ARM64_HAS_VIRT_HOST_EXTN +alternative_if_not ARM64_HAS_VIRT_HOST_EXTN + str lr, [sp, #-16]! hvc #0 + ldr lr, [sp], #16 ret alternative_else b __vhe_hyp_call nop + nop + nop alternative_endif ENDPROC(__kvm_call_hyp) diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index 358f27a..2cee779 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -39,7 +39,9 @@ .endm ENTRY(__vhe_hyp_call) + str lr, [sp, #-16]! do_el2_call + ldr lr, [sp], #16 /* * We used to rely on having an exception return to get * an implicit isb. In the E2H case, we don't have it anymore. -- 2.5.0
