Commit 87c021a8 authored by Dave Martin's avatar Dave Martin Committed by Catalin Marinas
Browse files

arm64/sve: Thin out initialisation sanity-checks for sve_max_vl 



Now that the kernel SVE support is reasonably mature, it is
excessive to default sve_max_vl to the invalid value -1 and then
sprinkle WARN_ON()s around the place to make sure it has been
initialised before use.  The cpufeatures code already runs pretty
early, and will ensure sve_max_vl gets initialised.

This patch initialises sve_max_vl to something sane that will be
supported by every SVE implementation, and removes most of the
sanity checks.

The checks in find_supported_vector_length() are retained for now.
If anything goes horribly wrong, we are likely to trip a check here
sooner or later.

Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent cb877710

arch/arm64/kernel/fpsimd.c

+4 −13
Original line number Diff line number Diff line
@@ -128,7 +128,7 @@ static int sve_default_vl = -1; 
#ifdef CONFIG_ARM64_SVE



/* Maximum supported vector length across all CPUs (initially poisoned) */

int __ro_after_init sve_max_vl = -1;

int __ro_after_init sve_max_vl = SVE_VL_MIN;

/* Set of available vector lengths, as vq_to_bit(vq): */

static __ro_after_init DECLARE_BITMAP(sve_vq_map, SVE_VQ_MAX);

static void __percpu *efi_sve_state;
@@ -359,22 +359,13 @@ static int sve_proc_do_default_vl(struct ctl_table *table, int write, 
		return ret;



	/* Writing -1 has the special meaning "set to max": */

	if (vl == -1) {

		/* Fail safe if sve_max_vl wasn't initialised */

		if (WARN_ON(!sve_vl_valid(sve_max_vl)))

			vl = SVE_VL_MIN;

		else

	if (vl == -1)

		vl = sve_max_vl;



		goto chosen;

	}



	if (!sve_vl_valid(vl))

		return -EINVAL;



	vl = find_supported_vector_length(vl);

chosen:

	sve_default_vl = vl;

	sve_default_vl = find_supported_vector_length(vl);

	return 0;

}

arch/arm64/kernel/ptrace.c

+0 −3
Original line number Diff line number Diff line
@@ -766,9 +766,6 @@ static void sve_init_header_from_task(struct user_sve_header *header, 
	vq = sve_vq_from_vl(header->vl);



	header->max_vl = sve_max_vl;

	if (WARN_ON(!sve_vl_valid(sve_max_vl)))

		header->max_vl = header->vl;



	header->size = SVE_PT_SIZE(vq, header->flags);

	header->max_size = SVE_PT_SIZE(sve_vq_from_vl(header->max_vl),

				      SVE_PT_REGS_SVE);

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