diff mbox series

[RFC,v2,15/22] selinux: introduce ebitmap_highest_set_bit()

Message ID 20241216164055.96267-15-cgoettsche@seltendoof.de (mailing list archive)
State Under Review
Delegated to: Paul Moore
Headers show
Series [RFC,v2,01/22] selinux: supply missing field initializers | expand

Commit Message

Christian Göttsche Dec. 16, 2024, 4:40 p.m. UTC
From: Christian Göttsche <cgzones@googlemail.com>

Introduce an ebitmap function to calculate the highest set bit.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
 security/selinux/ss/ebitmap.c | 27 +++++++++++++++++++++++++++
 security/selinux/ss/ebitmap.h |  1 +
 2 files changed, 28 insertions(+)

Comments

Paul Moore Jan. 8, 2025, 3 a.m. UTC | #1
On Dec 16, 2024 =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgoettsche@seltendoof.de> wrote:
> 
> Introduce an ebitmap function to calculate the highest set bit.
> 
> Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
> ---
>  security/selinux/ss/ebitmap.c | 27 +++++++++++++++++++++++++++
>  security/selinux/ss/ebitmap.h |  1 +
>  2 files changed, 28 insertions(+)
> 
> diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
> index 43bc19e21960..5d6b5b72b3e5 100644
> --- a/security/selinux/ss/ebitmap.c
> +++ b/security/selinux/ss/ebitmap.c
> @@ -257,6 +257,33 @@ int ebitmap_contains(const struct ebitmap *e1, const struct ebitmap *e2,
>  	return 1;
>  }
>  
> +u32 ebitmap_highest_set_bit(const struct ebitmap *e)
> +{
> +	const struct ebitmap_node *n;
> +	unsigned long unit;
> +	u32 pos = 0;
> +
> +	n = e->node;
> +	if (!n)
> +		return 0;
> +
> +	while (n->next)
> +		n = n->next;
> +
> +	for (unsigned int i = EBITMAP_UNIT_NUMS; i > 0; i--) {
> +		unit = n->maps[i - 1];
> +		if (unit == 0)
> +			continue;
> +
> +		pos = (i - 1) * EBITMAP_UNIT_SIZE;
> +		while (unit >>= 1)
> +			pos++;
> +		break;
> +	}
> +
> +	return n->startbit + pos;
> +}

Squash this patch with 16/22.  We generally don't add code that isn't
used, so squashing this with the caller in 16/22 ensures we have at
least one caller.

--
paul-moore.com
diff mbox series

Patch

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index 43bc19e21960..5d6b5b72b3e5 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -257,6 +257,33 @@  int ebitmap_contains(const struct ebitmap *e1, const struct ebitmap *e2,
 	return 1;
 }
 
+u32 ebitmap_highest_set_bit(const struct ebitmap *e)
+{
+	const struct ebitmap_node *n;
+	unsigned long unit;
+	u32 pos = 0;
+
+	n = e->node;
+	if (!n)
+		return 0;
+
+	while (n->next)
+		n = n->next;
+
+	for (unsigned int i = EBITMAP_UNIT_NUMS; i > 0; i--) {
+		unit = n->maps[i - 1];
+		if (unit == 0)
+			continue;
+
+		pos = (i - 1) * EBITMAP_UNIT_SIZE;
+		while (unit >>= 1)
+			pos++;
+		break;
+	}
+
+	return n->startbit + pos;
+}
+
 int ebitmap_get_bit(const struct ebitmap *e, u32 bit)
 {
 	const struct ebitmap_node *n;
diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h
index c9569998f287..12bb359e83ff 100644
--- a/security/selinux/ss/ebitmap.h
+++ b/security/selinux/ss/ebitmap.h
@@ -126,6 +126,7 @@  int ebitmap_and(struct ebitmap *dst, const struct ebitmap *e1,
 		const struct ebitmap *e2);
 int ebitmap_contains(const struct ebitmap *e1, const struct ebitmap *e2,
 		     u32 last_e2bit);
+u32 ebitmap_highest_set_bit(const struct ebitmap *e);
 int ebitmap_get_bit(const struct ebitmap *e, u32 bit);
 int ebitmap_set_bit(struct ebitmap *e, u32 bit, int value);
 void ebitmap_destroy(struct ebitmap *e);