From: Arnd Bergmann <arnd@arndb.de>

The write_pmuacr() function is only defined on arm64, so building the
driver on 32-bit arm now fails:

drivers/perf/arm_pmuv3.c: In function 'armv8pmu_enable_user_access':
drivers/perf/arm_pmuv3.c:784:17: error: implicit declaration of function 'write_pmuacr'; did you mean 'write_pmcr'? [-Wimplicit-function-declaration]

Add a compile-time check around the newly added code, as it is never
needed on arm32.

Fixes: 0bbff9ed8165 ("perf/arm_pmuv3: Add PMUv3.9 per counter EL0 access control")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/perf/arm_pmuv3.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index b6315ce71f19..e67918e0bbda 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -775,6 +775,7 @@ static void armv8pmu_enable_user_access(struct arm_pmu *cpu_pmu)
 	int i;
 	struct pmu_hw_events *cpuc = this_cpu_ptr(cpu_pmu->hw_events);
 
+#ifdef CONFIG_ARM64
 	if (is_pmuv3p9(cpu_pmu->pmuver)) {
 		u64 mask = 0;
 		for_each_set_bit(i, cpuc->used_mask, ARMPMU_MAX_HWEVENTS) {
@@ -782,7 +783,9 @@ static void armv8pmu_enable_user_access(struct arm_pmu *cpu_pmu)
 				mask |= BIT(i);
 		}
 		write_pmuacr(mask);
-	} else {
+	} else
+#endif
+	{
 		/* Clear any unused counters to avoid leaking their contents */
 		for_each_andnot_bit(i, cpu_pmu->cntr_mask, cpuc->used_mask,
 				    ARMPMU_MAX_HWEVENTS) {
-- 
2.39.5

On Tue, Oct 29, 2024 at 03:24:10PM +0000, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The write_pmuacr() function is only defined on arm64, so building the
> driver on 32-bit arm now fails:
> 
> drivers/perf/arm_pmuv3.c: In function 'armv8pmu_enable_user_access':
> drivers/perf/arm_pmuv3.c:784:17: error: implicit declaration of function 'write_pmuacr'; did you mean 'write_pmcr'? [-Wimplicit-function-declaration]
> 
> Add a compile-time check around the newly added code, as it is never
> needed on arm32.
> 
> Fixes: 0bbff9ed8165 ("perf/arm_pmuv3: Add PMUv3.9 per counter EL0 access control")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/perf/arm_pmuv3.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Cheers, Arnd. Rob already sent a fix for this [1], which I'll push out
shortly.

Will

[1] https://lore.kernel.org/linux-arm-kernel/20241029120602.4061566-2-robh@kernel.org/