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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: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Dave Martin 2018-06-01 11:10:13 +01:00 committed by Catalin Marinas
parent cb877710e5
commit 87c021a814
2 changed files with 4 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
arch/arm64/kernel/fpsimd.c
View File

@ -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
vl = sve_max_vl;
goto chosen;
}
if (vl == -1)
vl = sve_max_vl;
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;
}

3
arch/arm64/kernel/ptrace.c
View File

@ -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);