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riscv: misaligned: use on_each_cpu() for scalar misaligned access probing

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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 <cleger@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20250523101932.1594077-8-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
This commit is contained in:
Clément Léger
2025-05-23 12:19:24 +02:00
committed by Palmer Dabbelt
parent cf5a8abc65
commit 9f9f6fdd1d
1 changed files with 6 additions and 2 deletions
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arch/riscv/kernel/traps_misaligned.c
+6 -2
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@@ -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)