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* [PATCH] arm64: kvm: Modernize annotation for __bp_harden_hyp_vecs
@ 2020-02-18 12:44 Mark Brown
  2020-02-18 12:56 ` Marc Zyngier
  0 siblings, 1 reply; 8+ messages in thread
From: Mark Brown @ 2020-02-18 12:44 UTC (permalink / raw)
  To: Marc Zyngier, James Morse, Julien Thierry, Suzuki K Poulose
  Cc: Catalin Marinas, Mark Brown, Will Deacon, kvmarm,
	linux-arm-kernel

We have recently introduced new macros for annotating assembly symbols
for things that aren't C functions, SYM_CODE_START() and SYM_CODE_END(),
in an effort to clarify and simplify our annotations of assembly files.

Using these for __bp_harden_hyp_vecs is more involved than for most symbols
as this symbol is annotated quite unusually as rather than just have the
explicit symbol we define _start and _end symbols which we then use to
compute the length. This does not play at all nicely with the new style
macros. Since the size of the vectors is a known constant which won't vary
the simplest thing to do is simply to drop the separate _start and _end
symbols and just use a #define for the size.

Ideally we would have a build time assert to make sure we got this right
but we don't have such a thing for assembly code and given how unlikely
the size is to change it seems disproportionately difficult to write one
just for this.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/include/asm/kvm_mmu.h | 9 ++++-----
 arch/arm64/include/asm/mmu.h     | 5 ++++-
 arch/arm64/kernel/cpu_errata.c   | 2 +-
 arch/arm64/kvm/hyp/hyp-entry.S   | 4 ++--
 4 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 53d846f1bfe7..b5f723cf9599 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -480,7 +480,7 @@ static inline void *kvm_get_hyp_vector(void)
 	int slot = -1;
 
 	if (cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR) && data->fn) {
-		vect = kern_hyp_va(kvm_ksym_ref(__bp_harden_hyp_vecs_start));
+		vect = kern_hyp_va(kvm_ksym_ref(__bp_harden_hyp_vecs));
 		slot = data->hyp_vectors_slot;
 	}
 
@@ -509,14 +509,13 @@ static inline int kvm_map_vectors(void)
 	 *  HBP +  HEL2 -> use hardened vertors and use exec mapping
 	 */
 	if (cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR)) {
-		__kvm_bp_vect_base = kvm_ksym_ref(__bp_harden_hyp_vecs_start);
+		__kvm_bp_vect_base = kvm_ksym_ref(__bp_harden_hyp_vecs);
 		__kvm_bp_vect_base = kern_hyp_va(__kvm_bp_vect_base);
 	}
 
 	if (cpus_have_const_cap(ARM64_HARDEN_EL2_VECTORS)) {
-		phys_addr_t vect_pa = __pa_symbol(__bp_harden_hyp_vecs_start);
-		unsigned long size = (__bp_harden_hyp_vecs_end -
-				      __bp_harden_hyp_vecs_start);
+		phys_addr_t vect_pa = __pa_symbol(__bp_harden_hyp_vecs);
+		unsigned long size = __BP_HARDEN_HYP_VECS_SZ;
 
 		/*
 		 * Always allocate a spare vector slot, as we don't
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index e4d862420bb4..c6e811767a12 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -45,7 +45,10 @@ struct bp_hardening_data {
 
 #if (defined(CONFIG_HARDEN_BRANCH_PREDICTOR) ||	\
      defined(CONFIG_HARDEN_EL2_VECTORS))
-extern char __bp_harden_hyp_vecs_start[], __bp_harden_hyp_vecs_end[];
+
+#define __BP_HARDEN_HYP_VECS_SZ (BP_HARDEN_EL2_SLOTS * SZ_2K)
+
+extern char __bp_harden_hyp_vecs[];
 extern atomic_t arm64_el2_vector_last_slot;
 #endif  /* CONFIG_HARDEN_BRANCH_PREDICTOR || CONFIG_HARDEN_EL2_VECTORS */
 
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 703ad0a84f99..0af2201cefda 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -119,7 +119,7 @@ extern char __smccc_workaround_1_smc_end[];
 static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start,
 				const char *hyp_vecs_end)
 {
-	void *dst = lm_alias(__bp_harden_hyp_vecs_start + slot * SZ_2K);
+	void *dst = lm_alias(__bp_harden_hyp_vecs + slot * SZ_2K);
 	int i;
 
 	for (i = 0; i < SZ_2K; i += 0x80)
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 0aea8f9ab23d..8976276685a1 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -312,11 +312,11 @@ alternative_cb_end
 .endm
 
 	.align	11
-ENTRY(__bp_harden_hyp_vecs_start)
+SYM_CODE_START(__bp_harden_hyp_vecs)
 	.rept BP_HARDEN_EL2_SLOTS
 	generate_vectors
 	.endr
-ENTRY(__bp_harden_hyp_vecs_end)
+SYM_CODE_END(__bp_harden_hyp_vecs)
 
 	.popsection
 
-- 
2.20.1


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^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2020-02-18 13:46 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-02-18 12:44 [PATCH] arm64: kvm: Modernize annotation for __bp_harden_hyp_vecs Mark Brown
2020-02-18 12:56 ` Marc Zyngier
2020-02-18 13:06   ` Mark Brown
2020-02-18 13:14     ` Will Deacon
2020-02-18 13:45       ` Mark Brown
2020-02-18 13:09   ` Will Deacon
2020-02-18 13:29     ` Mark Brown
2020-02-18 13:35       ` Marc Zyngier

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