Unverified Commit 9f9f6fdd authored by Clément Léger's avatar Clément Léger Committed by Palmer Dabbelt
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riscv: misaligned: use on_each_cpu() for scalar misaligned access probing 



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: default avatarClément Léger <cleger@rivosinc.com>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Reviewed-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Tested-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20250523101932.1594077-8-cleger@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@dabbelt.com>
parent cf5a8abc

arch/riscv/kernel/traps_misaligned.c

+6 −2
Original line number Diff line number Diff line
@@ -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)