linux-kernel - [RFC PATCH 6/6] kvm: arm64: Remove hyp_symbol

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Message-Id: <20201119162543.78001-7-dbrazdil@google.com>
Date:   Thu, 19 Nov 2020 16:25:43 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Scull <ascull@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>, kernel-team@...roid.com,
        David Brazdil <dbrazdil@...gle.com>
Subject: [RFC PATCH 6/6] kvm: arm64: Remove hyp_symbol_addr

The helper was used to force PC-relative addressing in hyp code because
absolute addressing via constant-pools used to generate kernel VAs. This
was cumbersome and required programmers to remember to use the helper
whenever they wanted to take a pointer.

Now that hyp relocations are fixed up, there is no need for the helper
any logner. Remove it.

Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 arch/arm64/include/asm/kvm_asm.h         | 20 --------------------
 arch/arm64/kvm/hyp/include/hyp/switch.h  |  4 ++--
 arch/arm64/kvm/hyp/nvhe/hyp-smp.c        |  4 ++--
 arch/arm64/kvm/hyp/nvhe/psci-relay.c     |  4 ++--
 arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c |  2 +-
 5 files changed, 7 insertions(+), 27 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 1a86581e581e..1961d23c0c40 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -203,26 +203,6 @@ extern void __vgic_v3_init_lrs(void);
 
 extern u32 __kvm_get_mdcr_el2(void);
 
-/*
- * Obtain the PC-relative address of a kernel symbol
- * s: symbol
- *
- * The goal of this macro is to return a symbol's address based on a
- * PC-relative computation, as opposed to a loading the VA from a
- * constant pool or something similar. This works well for HYP, as an
- * absolute VA is guaranteed to be wrong. Only use this if trying to
- * obtain the address of a symbol (i.e. not something you obtained by
- * following a pointer).
- */
-#define hyp_symbol_addr(s)						\
-	({								\
-		typeof(s) *addr;					\
-		asm("adrp	%0, %1\n"				\
-		    "add	%0, %0, :lo12:%1\n"			\
-		    : "=r" (addr) : "S" (&s));				\
-		addr;							\
-	})
-
 #define __KVM_EXTABLE(from, to)						\
 	"	.pushsection	__kvm_ex_table, \"a\"\n"		\
 	"	.align		3\n"					\
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 84473574c2e7..54f4860cd87c 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -505,8 +505,8 @@ static inline void __kvm_unexpected_el2_exception(void)
 	struct exception_table_entry *entry, *end;
 	unsigned long elr_el2 = read_sysreg(elr_el2);
 
-	entry = hyp_symbol_addr(__start___kvm_ex_table);
-	end = hyp_symbol_addr(__stop___kvm_ex_table);
+	entry = &__start___kvm_ex_table;
+	end = &__stop___kvm_ex_table;
 
 	while (entry < end) {
 		addr = (unsigned long)&entry->insn + entry->insn;
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-smp.c b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
index ceb427aabb91..6870d9f3d4b7 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
@@ -33,8 +33,8 @@ unsigned long __hyp_per_cpu_offset(unsigned int cpu)
 	if (cpu >= ARRAY_SIZE(kvm_arm_hyp_percpu_base))
 		hyp_panic();
 
-	cpu_base_array = (unsigned long*)hyp_symbol_addr(kvm_arm_hyp_percpu_base);
+	cpu_base_array = (unsigned long*)(&kvm_arm_hyp_percpu_base[0]);
 	this_cpu_base = kern_hyp_va(cpu_base_array[cpu]);
-	elf_base = (unsigned long)hyp_symbol_addr(__per_cpu_start);
+	elf_base = (unsigned long)&__per_cpu_start;
 	return this_cpu_base - elf_base;
 }
diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
index 313ef42f0eab..f64380a49a72 100644
--- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -147,7 +147,7 @@ static int psci_cpu_suspend(u64 func_id, struct kvm_cpu_context *host_ctxt)
 	 * point if it is a deep sleep state.
 	 */
 	ret = psci_call(func_id, power_state,
-			__hyp_pa(hyp_symbol_addr(__kvm_hyp_cpu_entry)),
+			__hyp_pa(__kvm_hyp_cpu_entry),
 			__hyp_pa(cpu_params));
 
 	release_reset_state(cpu_state);
@@ -182,7 +182,7 @@ static int psci_cpu_on(u64 func_id, struct kvm_cpu_context *host_ctxt)
 		return PSCI_RET_ALREADY_ON;
 
 	ret = psci_call(func_id, mpidr,
-			__hyp_pa(hyp_symbol_addr(__kvm_hyp_cpu_entry)),
+			__hyp_pa(__kvm_hyp_cpu_entry),
 			__hyp_pa(cpu_params));
 
 	/*
diff --git a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
index 8f0585640241..87a54375bd6e 100644
--- a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
+++ b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
@@ -64,7 +64,7 @@ int __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu)
 	}
 
 	rd = kvm_vcpu_dabt_get_rd(vcpu);
-	addr  = hyp_symbol_addr(kvm_vgic_global_state)->vcpu_hyp_va;
+	addr  = kvm_vgic_global_state.vcpu_hyp_va;
 	addr += fault_ipa - vgic->vgic_cpu_base;
 
 	if (kvm_vcpu_dabt_iswrite(vcpu)) {
-- 
2.29.2.299.gdc1121823c-goog