From 9f9f6fdd1dc6791bcfe251160a96a446199f85ce Mon Sep 17 00:00:00 2001 From: =?utf8?q?Cl=C3=A9ment=20L=C3=A9ger?= Date: Fri, 23 May 2025 12:19:24 +0200 Subject: [PATCH] riscv: misaligned: use on_each_cpu() for scalar misaligned access probing MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit schedule_on_each_cpu() was used without any good reason while documented as very slow. This call was in the boot path, so better use on_each_cpu() for scalar misaligned checking. Vector misaligned check still needs to use schedule_on_each_cpu() since it requires irqs to be enabled but that's less of a problem since this code is ran in a kthread. Add a comment to explicit that. Signed-off-by: Clément Léger Reviewed-by: Andrew Jones Reviewed-by: Charlie Jenkins Tested-by: Charlie Jenkins Link: https://lore.kernel.org/r/20250523101932.1594077-8-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/traps_misaligned.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index 592b1a28e897..34b4a4e9dfca 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -627,6 +627,10 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void) { int cpu; + /* + * While being documented as very slow, schedule_on_each_cpu() is used since + * kernel_vector_begin() expects irqs to be enabled or it will panic() + */ schedule_on_each_cpu(check_vector_unaligned_access_emulated); for_each_online_cpu(cpu) @@ -647,7 +651,7 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void) static bool unaligned_ctl __read_mostly; -static void check_unaligned_access_emulated(struct work_struct *work __always_unused) +static void check_unaligned_access_emulated(void *arg __always_unused) { int cpu = smp_processor_id(); long *mas_ptr = per_cpu_ptr(&misaligned_access_speed, cpu); @@ -688,7 +692,7 @@ bool __init check_unaligned_access_emulated_all_cpus(void) * accesses emulated since tasks requesting such control can run on any * CPU. */ - schedule_on_each_cpu(check_unaligned_access_emulated); + on_each_cpu(check_unaligned_access_emulated, NULL, 1); for_each_online_cpu(cpu) if (per_cpu(misaligned_access_speed, cpu) -- 2.25.1