arm64: capabilities: Update prototype for enable call back

We issue the enable() call back for all CPU hwcaps capabilities
available on the system, on all the CPUs. So far we have ignored
the argument passed to the call back, which had a prototype to
accept a "void *" for use with on_each_cpu() and later with
stop_machine(). However, with commit 0a0d111d40fd1
("arm64: cpufeature: Pass capability structure to ->enable callback"),
there are some users of the argument who wants the matching capability
struct pointer where there are multiple matching criteria for a single
capability. Clean up the declaration of the call back to make it clear.

 1) Renamed to cpu_enable(), to imply taking necessary actions on the
    called CPU for the entry.
 2) Pass const pointer to the capability, to allow the call back to
    check the entry. (e.,g to check if any action is needed on the CPU)
 3) We don't care about the result of the call back, turning this to
    a void.

Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: James Morse <james.morse@arm.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Dave Martin <dave.martin@arm.com>
[suzuki: convert more users, rename call back and drop results]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 24 insertions, 18 deletions

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index de4ea6a0208e..d66f64b81557 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -909,7 +909,8 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 						     ID_AA64PFR0_CSV3_SHIFT);
 }
 
-static int kpti_install_ng_mappings(void *__unused)
+static void
+kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
 {
 	typedef void (kpti_remap_fn)(int, int, phys_addr_t);
 	extern kpti_remap_fn idmap_kpti_install_ng_mappings;
@@ -919,7 +920,7 @@ static int kpti_install_ng_mappings(void *__unused)
 	int cpu = smp_processor_id();
 
 	if (kpti_applied)
-		return 0;
+		return;
 
 	remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);
 
@@ -930,7 +931,7 @@ static int kpti_install_ng_mappings(void *__unused)
 	if (!cpu)
 		kpti_applied = true;
 
-	return 0;
+	return;
 }
 
 static int __init parse_kpti(char *str)
@@ -947,7 +948,7 @@ static int __init parse_kpti(char *str)
 __setup("kpti=", parse_kpti);
 #endif	/* CONFIG_UNMAP_KERNEL_AT_EL0 */
 
-static int cpu_copy_el2regs(void *__unused)
+static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
 {
 	/*
 	 * Copy register values that aren't redirected by hardware.
@@ -959,8 +960,6 @@ static int cpu_copy_el2regs(void *__unused)
 	 */
 	if (!alternatives_applied)
 		write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
-
-	return 0;
 }
 
 static const struct arm64_cpu_capabilities arm64_features[] = {
@@ -984,7 +983,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.field_pos = ID_AA64MMFR1_PAN_SHIFT,
 		.sign = FTR_UNSIGNED,
 		.min_field_value = 1,
-		.enable = cpu_enable_pan,
+		.cpu_enable = cpu_enable_pan,
 	},
 #endif /* CONFIG_ARM64_PAN */
 #if defined(CONFIG_AS_LSE) && defined(CONFIG_ARM64_LSE_ATOMICS)
@@ -1032,7 +1031,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.capability = ARM64_HAS_VIRT_HOST_EXTN,
 		.def_scope = SCOPE_SYSTEM,
 		.matches = runs_at_el2,
-		.enable = cpu_copy_el2regs,
+		.cpu_enable = cpu_copy_el2regs,
 	},
 	{
 		.desc = "32-bit EL0 Support",
@@ -1056,7 +1055,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.capability = ARM64_UNMAP_KERNEL_AT_EL0,
 		.def_scope = SCOPE_SYSTEM,
 		.matches = unmap_kernel_at_el0,
-		.enable = kpti_install_ng_mappings,
+		.cpu_enable = kpti_install_ng_mappings,
 	},
 #endif
 	{
@@ -1087,7 +1086,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.field_pos = ID_AA64PFR0_SVE_SHIFT,
 		.min_field_value = ID_AA64PFR0_SVE,
 		.matches = has_cpuid_feature,
-		.enable = sve_kernel_enable,
+		.cpu_enable = sve_kernel_enable,
 	},
 #endif /* CONFIG_ARM64_SVE */
 #ifdef CONFIG_ARM64_RAS_EXTN
@@ -1100,7 +1099,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.sign = FTR_UNSIGNED,
 		.field_pos = ID_AA64PFR0_RAS_SHIFT,
 		.min_field_value = ID_AA64PFR0_RAS_V1,
-		.enable = cpu_clear_disr,
+		.cpu_enable = cpu_clear_disr,
 	},
 #endif /* CONFIG_ARM64_RAS_EXTN */
 	{
@@ -1260,6 +1259,14 @@ void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
 	}
 }
 
+static int __enable_cpu_capability(void *arg)
+{
+	const struct arm64_cpu_capabilities *cap = arg;
+
+	cap->cpu_enable(cap);
+	return 0;
+}
+
 /*
  * Run through the enabled capabilities and enable() it on all active
  * CPUs
@@ -1275,14 +1282,15 @@ void __init enable_cpu_capabilities(const struct arm64_cpu_capabilities *caps)
 		/* Ensure cpus_have_const_cap(num) works */
 		static_branch_enable(&cpu_hwcap_keys[num]);
 
-		if (caps->enable) {
+		if (caps->cpu_enable) {
 			/*
 			 * Use stop_machine() as it schedules the work allowing
 			 * us to modify PSTATE, instead of on_each_cpu() which
 			 * uses an IPI, giving us a PSTATE that disappears when
 			 * we return.
 			 */
-			stop_machine(caps->enable, (void *)caps, cpu_online_mask);
+			stop_machine(__enable_cpu_capability, (void *)caps,
+				     cpu_online_mask);
 		}
 	}
 }
@@ -1325,8 +1333,8 @@ verify_local_cpu_features(const struct arm64_cpu_capabilities *caps_list)
 					smp_processor_id(), caps->desc);
 			cpu_die_early();
 		}
-		if (caps->enable)
-			caps->enable((void *)caps);
+		if (caps->cpu_enable)
+			caps->cpu_enable(caps);
 	}
 }
 
@@ -1544,10 +1552,8 @@ static int __init enable_mrs_emulation(void)
 
 core_initcall(enable_mrs_emulation);
 
-int cpu_clear_disr(void *__unused)
+void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused)
 {
 	/* Firmware may have left a deferred SError in this register. */
 	write_sysreg_s(0, SYS_DISR_EL1);
-
-	return 0;
 }