From 5513394de681a456ad728ae775c58c41aff14011 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 22 Apr 2024 15:13:03 +0100 Subject: [PATCH] KVM: arm64: nv: Work around lack of pauth support in old toolchains We still support GCC 8.x, and it appears that this toolchain usually comes with an assembler that does not understand "pauth" as a valid architectural extension. This results in the NV ERETAx code breaking the build, as it relies on this extention to make use of the PACGA instruction (required by assemblers such as LLVM's). Work around it by hand-assembling the instruction, which removes the requirement for any assembler directive. Fixes: 6ccc971ee2c6 ("KVM: arm64: nv: Add emulation for ERETAx instructions") Reported-by: Linaro Kernel Functional Testing Suggested-by: Mark Rutland Acked-by: Arnd Bergmann Signed-off-by: Marc Zyngier --- arch/arm64/kvm/pauth.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/pauth.c b/arch/arm64/kvm/pauth.c index a3a5c404375bc..d5eb3ae876be4 100644 --- a/arch/arm64/kvm/pauth.c +++ b/arch/arm64/kvm/pauth.c @@ -14,9 +14,20 @@ #include +#include #include #include +/* PACGA Xd, Xn, Xm */ +#define PACGA(d,n,m) \ + asm volatile(__DEFINE_ASM_GPR_NUMS \ + ".inst 0x9AC03000 |" \ + "(.L__gpr_num_%[Rd] << 0) |" \ + "(.L__gpr_num_%[Rn] << 5) |" \ + "(.L__gpr_num_%[Rm] << 16)\n" \ + : [Rd] "=r" ((d)) \ + : [Rn] "r" ((n)), [Rm] "r" ((m))) + static u64 compute_pac(struct kvm_vcpu *vcpu, u64 ptr, struct ptrauth_key ikey) { @@ -36,8 +47,7 @@ static u64 compute_pac(struct kvm_vcpu *vcpu, u64 ptr, __ptrauth_key_install_nosync(APGA, ikey); isb(); - asm volatile(ARM64_ASM_PREAMBLE ".arch_extension pauth\n" - "pacga %0, %1, %2" : "=r" (pac) : "r" (ptr), "r" (mod)); + PACGA(pac, ptr, mod); isb(); __ptrauth_key_install_nosync(APGA, gkey); -- 2.30.2