Unverified Commit 8d20a739 authored by Jesse Taube's avatar Jesse Taube Committed by Palmer Dabbelt
Browse files

RISC-V: Check scalar unaligned access on all CPUs 



Originally, the check_unaligned_access_emulated_all_cpus function
only checked the boot hart. This fixes the function to check all
harts.

Fixes: 71c54b3d ("riscv: report misaligned accesses emulation to hwprobe")
Signed-off-by: default avatarJesse Taube <jesse@rivosinc.com>
Reviewed-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Reviewed-by: default avatarEvan Green <evan@rivosinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241017-jesse_unaligned_vector-v10-1-5b33500160f8@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 9852d85e

arch/riscv/include/asm/cpufeature.h

+2 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 


#include <linux/bitmap.h>

#include <linux/jump_label.h>

#include <linux/workqueue.h>

#include <asm/hwcap.h>

#include <asm/alternative-macros.h>

#include <asm/errno.h>
@@ -60,6 +61,7 @@ void riscv_user_isa_enable(void); 


#if defined(CONFIG_RISCV_MISALIGNED)

bool check_unaligned_access_emulated_all_cpus(void);

void check_unaligned_access_emulated(struct work_struct *work __always_unused);

void unaligned_emulation_finish(void);

bool unaligned_ctl_available(void);

DECLARE_PER_CPU(long, misaligned_access_speed);

arch/riscv/kernel/traps_misaligned.c

+7 −7
Original line number Diff line number Diff line
@@ -526,11 +526,11 @@ int handle_misaligned_store(struct pt_regs *regs) 
	return 0;

}



static bool check_unaligned_access_emulated(int cpu)

void check_unaligned_access_emulated(struct work_struct *work __always_unused)

{

	int cpu = smp_processor_id();

	long *mas_ptr = per_cpu_ptr(&misaligned_access_speed, cpu);

	unsigned long tmp_var, tmp_val;

	bool misaligned_emu_detected;



	*mas_ptr = RISCV_HWPROBE_MISALIGNED_SCALAR_UNKNOWN;
@@ -538,19 +538,16 @@ static bool check_unaligned_access_emulated(int cpu) 
		"       "REG_L" %[tmp], 1(%[ptr])\n"

		: [tmp] "=r" (tmp_val) : [ptr] "r" (&tmp_var) : "memory");



	misaligned_emu_detected = (*mas_ptr == RISCV_HWPROBE_MISALIGNED_SCALAR_EMULATED);

	/*

	 * If unaligned_ctl is already set, this means that we detected that all

	 * CPUS uses emulated misaligned access at boot time. If that changed

	 * when hotplugging the new cpu, this is something we don't handle.

	 */

	if (unlikely(unaligned_ctl && !misaligned_emu_detected)) {

	if (unlikely(unaligned_ctl && (*mas_ptr != RISCV_HWPROBE_MISALIGNED_SCALAR_EMULATED))) {

		pr_crit("CPU misaligned accesses non homogeneous (expected all emulated)\n");

		while (true)

			cpu_relax();

	}



	return misaligned_emu_detected;

}



bool check_unaligned_access_emulated_all_cpus(void)
@@ -562,8 +559,11 @@ bool 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);



	for_each_online_cpu(cpu)

		if (!check_unaligned_access_emulated(cpu))

		if (per_cpu(misaligned_access_speed, cpu)

		    != RISCV_HWPROBE_MISALIGNED_SCALAR_EMULATED)

			return false;



	unaligned_ctl = true;