prepare_selector(), read_protection_region() and write_protection_region()
differ significantly between arm32 and arm64. Thus, move these functions
to their specific folders.
GENERATE_{WRITE/READ}_PR_REG_CASE are duplicated for arm32 and arm64 so
as to improve the code readability.
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
---
Changes from -
v1..v2 - New patch introduced in v3.
 xen/arch/arm/mpu/Makefile       |   1 +
 xen/arch/arm/mpu/arm64/Makefile |   1 +
 xen/arch/arm/mpu/arm64/mm.c     | 130 ++++++++++++++++++++++++++++++++
 xen/arch/arm/mpu/mm.c           | 117 ----------------------------
 4 files changed, 132 insertions(+), 117 deletions(-)
 create mode 100644 xen/arch/arm/mpu/arm64/Makefile
 create mode 100644 xen/arch/arm/mpu/arm64/mm.c
diff --git a/xen/arch/arm/mpu/Makefile b/xen/arch/arm/mpu/Makefile
index 9359d79332..4963c8b550 100644
--- a/xen/arch/arm/mpu/Makefile
+++ b/xen/arch/arm/mpu/Makefile
@@ -1,4 +1,5 @@
 obj-$(CONFIG_ARM_32) += arm32/
+obj-$(CONFIG_ARM_64) += arm64/
 obj-y += mm.o
 obj-y += p2m.o
 obj-y += setup.init.o
diff --git a/xen/arch/arm/mpu/arm64/Makefile b/xen/arch/arm/mpu/arm64/Makefile
new file mode 100644
index 0000000000..b18cec4836
--- /dev/null
+++ b/xen/arch/arm/mpu/arm64/Makefile
@@ -0,0 +1 @@
+obj-y += mm.o
diff --git a/xen/arch/arm/mpu/arm64/mm.c b/xen/arch/arm/mpu/arm64/mm.c
new file mode 100644
index 0000000000..a978c1fc6e
--- /dev/null
+++ b/xen/arch/arm/mpu/arm64/mm.c
@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <xen/bug.h>
+#include <xen/types.h>
+#include <asm/mpu.h>
+#include <asm/sysregs.h>
+#include <asm/system.h>
+
+/*
+ * The following are needed for the cases: GENERATE_WRITE_PR_REG_CASE
+ * and GENERATE_READ_PR_REG_CASE with num==0
+ */
+#define PRBAR0_EL2 PRBAR_EL2
+#define PRLAR0_EL2 PRLAR_EL2
+
+#define PRBAR_EL2_(n)   PRBAR##n##_EL2
+#define PRLAR_EL2_(n)   PRLAR##n##_EL2
+
+#define GENERATE_WRITE_PR_REG_CASE(num, pr)                                 \
+    case num:                                                               \
+    {                                                                       \
+        WRITE_SYSREG(pr->prbar.bits & ~MPU_REGION_RES0, PRBAR_EL2_(num));   \
+        WRITE_SYSREG(pr->prlar.bits & ~MPU_REGION_RES0, PRLAR_EL2_(num));   \
+        break;                                                              \
+    }
+
+#define GENERATE_READ_PR_REG_CASE(num, pr)                      \
+    case num:                                                   \
+    {                                                           \
+        pr->prbar.bits = READ_SYSREG(PRBAR_EL2_(num));          \
+        pr->prlar.bits = READ_SYSREG(PRLAR_EL2_(num));          \
+        break;                                                  \
+    }
+
+/*
+ * Armv8-R supports direct access and indirect access to the MPU regions through
+ * registers:
+ *  - indirect access involves changing the MPU region selector, issuing an isb
+ *    barrier and accessing the selected region through specific registers
+ *  - direct access involves accessing specific registers that point to
+ *    specific MPU regions, without changing the selector, avoiding the use of
+ *    a barrier.
+ * For Arm64 the PR{B,L}AR_ELx (for n=0) and PR{B,L}AR<n>_ELx (for n=1..15) are
+ * used for the direct access to the regions selected by
+ * PRSELR_EL2.REGION<7:4>:n, so 16 regions can be directly accessed when the
+ * selector is a multiple of 16, giving access to all the supported memory
+ * regions.
+ */
+static void prepare_selector(uint8_t *sel)
+{
+    uint8_t cur_sel = *sel;
+
+    /*
+     * {read,write}_protection_region works using the direct access to the 0..15
+     * regions, so in order to save the isb() overhead, change the PRSELR_EL2
+     * only when needed, so when the upper 4 bits of the selector will change.
+     */
+    cur_sel &= 0xF0U;
+    if ( READ_SYSREG(PRSELR_EL2) != cur_sel )
+    {
+        WRITE_SYSREG(cur_sel, PRSELR_EL2);
+        isb();
+    }
+    *sel = *sel & 0xFU;
+}
+
+void read_protection_region(pr_t *pr_read, uint8_t sel)
+{
+    prepare_selector(&sel);
+
+    switch ( sel )
+    {
+        GENERATE_READ_PR_REG_CASE(0, pr_read);
+        GENERATE_READ_PR_REG_CASE(1, pr_read);
+        GENERATE_READ_PR_REG_CASE(2, pr_read);
+        GENERATE_READ_PR_REG_CASE(3, pr_read);
+        GENERATE_READ_PR_REG_CASE(4, pr_read);
+        GENERATE_READ_PR_REG_CASE(5, pr_read);
+        GENERATE_READ_PR_REG_CASE(6, pr_read);
+        GENERATE_READ_PR_REG_CASE(7, pr_read);
+        GENERATE_READ_PR_REG_CASE(8, pr_read);
+        GENERATE_READ_PR_REG_CASE(9, pr_read);
+        GENERATE_READ_PR_REG_CASE(10, pr_read);
+        GENERATE_READ_PR_REG_CASE(11, pr_read);
+        GENERATE_READ_PR_REG_CASE(12, pr_read);
+        GENERATE_READ_PR_REG_CASE(13, pr_read);
+        GENERATE_READ_PR_REG_CASE(14, pr_read);
+        GENERATE_READ_PR_REG_CASE(15, pr_read);
+    default:
+        BUG(); /* Can't happen */
+        break;
+    }
+}
+
+void write_protection_region(const pr_t *pr_write, uint8_t sel)
+{
+    prepare_selector(&sel);
+
+    switch ( sel )
+    {
+        GENERATE_WRITE_PR_REG_CASE(0, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(1, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(2, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(3, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(4, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(5, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(6, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(7, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(8, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(9, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(10, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(11, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(12, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(13, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(14, pr_write);
+        GENERATE_WRITE_PR_REG_CASE(15, pr_write);
+    default:
+        BUG(); /* Can't happen */
+        break;
+    }
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c
index 3d37beab57..7ab68fc8c7 100644
--- a/xen/arch/arm/mpu/mm.c
+++ b/xen/arch/arm/mpu/mm.c
@@ -29,35 +29,6 @@ DECLARE_BITMAP(xen_mpumap_mask, MAX_MPU_REGION_NR) \
 /* EL2 Xen MPU memory region mapping table. */
 pr_t __cacheline_aligned __section(".data") xen_mpumap[MAX_MPU_REGION_NR];
 
-#ifdef CONFIG_ARM_64
-/*
- * The following are needed for the cases: GENERATE_WRITE_PR_REG_CASE
- * and GENERATE_READ_PR_REG_CASE with num==0
- */
-#define PRBAR0_EL2 PRBAR_EL2
-#define PRLAR0_EL2 PRLAR_EL2
-
-#define PRBAR_EL2_(n)   PRBAR##n##_EL2
-#define PRLAR_EL2_(n)   PRLAR##n##_EL2
-
-#endif /* CONFIG_ARM_64 */
-
-#define GENERATE_WRITE_PR_REG_CASE(num, pr)                                 \
-    case num:                                                               \
-    {                                                                       \
-        WRITE_SYSREG(pr->prbar.bits & ~MPU_REGION_RES0, PRBAR_EL2_(num));   \
-        WRITE_SYSREG(pr->prlar.bits & ~MPU_REGION_RES0, PRLAR_EL2_(num));   \
-        break;                                                              \
-    }
-
-#define GENERATE_READ_PR_REG_CASE(num, pr)                      \
-    case num:                                                   \
-    {                                                           \
-        pr->prbar.bits = READ_SYSREG(PRBAR_EL2_(num));          \
-        pr->prlar.bits = READ_SYSREG(PRLAR_EL2_(num));          \
-        break;                                                  \
-    }
-
 static void __init __maybe_unused build_assertions(void)
 {
     /*
@@ -69,94 +40,6 @@ static void __init __maybe_unused build_assertions(void)
 }
 
 #ifdef CONFIG_ARM_64
-/*
- * Armv8-R supports direct access and indirect access to the MPU regions through
- * registers:
- *  - indirect access involves changing the MPU region selector, issuing an isb
- *    barrier and accessing the selected region through specific registers
- *  - direct access involves accessing specific registers that point to
- *    specific MPU regions, without changing the selector, avoiding the use of
- *    a barrier.
- * For Arm64 the PR{B,L}AR_ELx (for n=0) and PR{B,L}AR<n>_ELx (for n=1..15) are
- * used for the direct access to the regions selected by
- * PRSELR_EL2.REGION<7:4>:n, so 16 regions can be directly accessed when the
- * selector is a multiple of 16, giving access to all the supported memory
- * regions.
- */
-static void prepare_selector(uint8_t *sel)
-{
-    uint8_t cur_sel = *sel;
-
-    /*
-     * {read,write}_protection_region works using the direct access to the 0..15
-     * regions, so in order to save the isb() overhead, change the PRSELR_EL2
-     * only when needed, so when the upper 4 bits of the selector will change.
-     */
-    cur_sel &= 0xF0U;
-    if ( READ_SYSREG(PRSELR_EL2) != cur_sel )
-    {
-        WRITE_SYSREG(cur_sel, PRSELR_EL2);
-        isb();
-    }
-    *sel &= 0xFU;
-}
-
-void read_protection_region(pr_t *pr_read, uint8_t sel)
-{
-    prepare_selector(&sel);
-
-    switch ( sel )
-    {
-        GENERATE_READ_PR_REG_CASE(0, pr_read);
-        GENERATE_READ_PR_REG_CASE(1, pr_read);
-        GENERATE_READ_PR_REG_CASE(2, pr_read);
-        GENERATE_READ_PR_REG_CASE(3, pr_read);
-        GENERATE_READ_PR_REG_CASE(4, pr_read);
-        GENERATE_READ_PR_REG_CASE(5, pr_read);
-        GENERATE_READ_PR_REG_CASE(6, pr_read);
-        GENERATE_READ_PR_REG_CASE(7, pr_read);
-        GENERATE_READ_PR_REG_CASE(8, pr_read);
-        GENERATE_READ_PR_REG_CASE(9, pr_read);
-        GENERATE_READ_PR_REG_CASE(10, pr_read);
-        GENERATE_READ_PR_REG_CASE(11, pr_read);
-        GENERATE_READ_PR_REG_CASE(12, pr_read);
-        GENERATE_READ_PR_REG_CASE(13, pr_read);
-        GENERATE_READ_PR_REG_CASE(14, pr_read);
-        GENERATE_READ_PR_REG_CASE(15, pr_read);
-    default:
-        BUG(); /* Can't happen */
-        break;
-    }
-}
-
-void write_protection_region(const pr_t *pr_write, uint8_t sel)
-{
-    prepare_selector(&sel);
-
-    switch ( sel )
-    {
-        GENERATE_WRITE_PR_REG_CASE(0, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(1, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(2, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(3, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(4, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(5, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(6, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(7, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(8, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(9, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(10, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(11, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(12, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(13, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(14, pr_write);
-        GENERATE_WRITE_PR_REG_CASE(15, pr_write);
-    default:
-        BUG(); /* Can't happen */
-        break;
-    }
-}
-
 pr_t pr_of_addr(paddr_t base, paddr_t limit, unsigned int flags)
 {
     unsigned int attr_idx = PAGE_AI_MASK(flags);
-- 
2.25.1Hi Ayan,
> On 11 Jun 2025, at 15:35, Ayan Kumar Halder <ayan.kumar.halder@amd.com> wrote:
> 
> prepare_selector(), read_protection_region() and write_protection_region()
> differ significantly between arm32 and arm64. Thus, move these functions
> to their specific folders.
   ^— NIT: “to sub-arch specific folder”? What do you think?
> 
> GENERATE_{WRITE/READ}_PR_REG_CASE are duplicated for arm32 and arm64 so
> as to improve the code readability.
It reads a bit hard in this way, what about:
“Also the macro GENERATE_{WRITE/READ}_PR_REG_CASE are moved, in order to
keep them in the same file of their usage and improve readability"
> 
> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
> ---
> Changes from -
> 
> v1..v2 - New patch introduced in v3.
> 
> xen/arch/arm/mpu/Makefile       |   1 +
> xen/arch/arm/mpu/arm64/Makefile |   1 +
> xen/arch/arm/mpu/arm64/mm.c     | 130 ++++++++++++++++++++++++++++++++
> xen/arch/arm/mpu/mm.c           | 117 ----------------------------
> 4 files changed, 132 insertions(+), 117 deletions(-)
> create mode 100644 xen/arch/arm/mpu/arm64/Makefile
> create mode 100644 xen/arch/arm/mpu/arm64/mm.c
> 
> diff --git a/xen/arch/arm/mpu/Makefile b/xen/arch/arm/mpu/Makefile
> index 9359d79332..4963c8b550 100644
> --- a/xen/arch/arm/mpu/Makefile
> +++ b/xen/arch/arm/mpu/Makefile
> @@ -1,4 +1,5 @@
> obj-$(CONFIG_ARM_32) += arm32/
> +obj-$(CONFIG_ARM_64) += arm64/
> obj-y += mm.o
> obj-y += p2m.o
> obj-y += setup.init.o
> diff --git a/xen/arch/arm/mpu/arm64/Makefile b/xen/arch/arm/mpu/arm64/Makefile
> new file mode 100644
> index 0000000000..b18cec4836
> --- /dev/null
> +++ b/xen/arch/arm/mpu/arm64/Makefile
> @@ -0,0 +1 @@
> +obj-y += mm.o
> diff --git a/xen/arch/arm/mpu/arm64/mm.c b/xen/arch/arm/mpu/arm64/mm.c
> new file mode 100644
> index 0000000000..a978c1fc6e
> --- /dev/null
> +++ b/xen/arch/arm/mpu/arm64/mm.c
> @@ -0,0 +1,130 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#include <xen/bug.h>
> +#include <xen/types.h>
> +#include <asm/mpu.h>
> +#include <asm/sysregs.h>
> +#include <asm/system.h>
> +
> +/*
> + * The following are needed for the cases: GENERATE_WRITE_PR_REG_CASE
> + * and GENERATE_READ_PR_REG_CASE with num==0
> + */
> +#define PRBAR0_EL2 PRBAR_EL2
> +#define PRLAR0_EL2 PRLAR_EL2
> +
> +#define PRBAR_EL2_(n)   PRBAR##n##_EL2
> +#define PRLAR_EL2_(n)   PRLAR##n##_EL2
> +
> +#define GENERATE_WRITE_PR_REG_CASE(num, pr)                                 \
> +    case num:                                                               \
> +    {                                                                       \
> +        WRITE_SYSREG(pr->prbar.bits & ~MPU_REGION_RES0, PRBAR_EL2_(num));   \
> +        WRITE_SYSREG(pr->prlar.bits & ~MPU_REGION_RES0, PRLAR_EL2_(num));   \
> +        break;                                                              \
> +    }
> +
> +#define GENERATE_READ_PR_REG_CASE(num, pr)                      \
> +    case num:                                                   \
> +    {                                                           \
> +        pr->prbar.bits = READ_SYSREG(PRBAR_EL2_(num));          \
> +        pr->prlar.bits = READ_SYSREG(PRLAR_EL2_(num));          \
> +        break;                                                  \
> +    }
> +
> +/*
> + * Armv8-R supports direct access and indirect access to the MPU regions through
> + * registers:
> + *  - indirect access involves changing the MPU region selector, issuing an isb
> + *    barrier and accessing the selected region through specific registers
> + *  - direct access involves accessing specific registers that point to
> + *    specific MPU regions, without changing the selector, avoiding the use of
> + *    a barrier.
> + * For Arm64 the PR{B,L}AR_ELx (for n=0) and PR{B,L}AR<n>_ELx (for n=1..15) are
> + * used for the direct access to the regions selected by
> + * PRSELR_EL2.REGION<7:4>:n, so 16 regions can be directly accessed when the
> + * selector is a multiple of 16, giving access to all the supported memory
> + * regions.
> + */
> +static void prepare_selector(uint8_t *sel)
> +{
> +    uint8_t cur_sel = *sel;
> +
> +    /*
> +     * {read,write}_protection_region works using the direct access to the 0..15
> +     * regions, so in order to save the isb() overhead, change the PRSELR_EL2
> +     * only when needed, so when the upper 4 bits of the selector will change.
> +     */
> +    cur_sel &= 0xF0U;
> +    if ( READ_SYSREG(PRSELR_EL2) != cur_sel )
> +    {
> +        WRITE_SYSREG(cur_sel, PRSELR_EL2);
> +        isb();
> +    }
> +    *sel = *sel & 0xFU;
This one is different in the original file (*sel &= 0xFU;)
The rest looks good to me!
With the above fixed:
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Cheers,
Luca
                
            
On 13/06/2025 16:08, Luca Fancellu wrote:
> Hi Ayan,
Hi Luca,
>
>> On 11 Jun 2025, at 15:35, Ayan Kumar Halder <ayan.kumar.halder@amd.com> wrote:
>>
>> prepare_selector(), read_protection_region() and write_protection_region()
>> differ significantly between arm32 and arm64. Thus, move these functions
>> to their specific folders.
>     ^— NIT: “to sub-arch specific folder”? What do you think?
yes
>
>> GENERATE_{WRITE/READ}_PR_REG_CASE are duplicated for arm32 and arm64 so
>> as to improve the code readability.
> It reads a bit hard in this way, what about:
>
> “Also the macro GENERATE_{WRITE/READ}_PR_REG_CASE are moved, in order to
> keep them in the same file of their usage and improve readability"
yes, this reads better.
>
>> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
>> ---
>> Changes from -
>>
>> v1..v2 - New patch introduced in v3.
>>
>> xen/arch/arm/mpu/Makefile       |   1 +
>> xen/arch/arm/mpu/arm64/Makefile |   1 +
>> xen/arch/arm/mpu/arm64/mm.c     | 130 ++++++++++++++++++++++++++++++++
>> xen/arch/arm/mpu/mm.c           | 117 ----------------------------
>> 4 files changed, 132 insertions(+), 117 deletions(-)
>> create mode 100644 xen/arch/arm/mpu/arm64/Makefile
>> create mode 100644 xen/arch/arm/mpu/arm64/mm.c
>>
>> diff --git a/xen/arch/arm/mpu/Makefile b/xen/arch/arm/mpu/Makefile
>> index 9359d79332..4963c8b550 100644
>> --- a/xen/arch/arm/mpu/Makefile
>> +++ b/xen/arch/arm/mpu/Makefile
>> @@ -1,4 +1,5 @@
>> obj-$(CONFIG_ARM_32) += arm32/
>> +obj-$(CONFIG_ARM_64) += arm64/
>> obj-y += mm.o
>> obj-y += p2m.o
>> obj-y += setup.init.o
>> diff --git a/xen/arch/arm/mpu/arm64/Makefile b/xen/arch/arm/mpu/arm64/Makefile
>> new file mode 100644
>> index 0000000000..b18cec4836
>> --- /dev/null
>> +++ b/xen/arch/arm/mpu/arm64/Makefile
>> @@ -0,0 +1 @@
>> +obj-y += mm.o
>> diff --git a/xen/arch/arm/mpu/arm64/mm.c b/xen/arch/arm/mpu/arm64/mm.c
>> new file mode 100644
>> index 0000000000..a978c1fc6e
>> --- /dev/null
>> +++ b/xen/arch/arm/mpu/arm64/mm.c
>> @@ -0,0 +1,130 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +
>> +#include <xen/bug.h>
>> +#include <xen/types.h>
>> +#include <asm/mpu.h>
>> +#include <asm/sysregs.h>
>> +#include <asm/system.h>
>> +
>> +/*
>> + * The following are needed for the cases: GENERATE_WRITE_PR_REG_CASE
>> + * and GENERATE_READ_PR_REG_CASE with num==0
>> + */
>> +#define PRBAR0_EL2 PRBAR_EL2
>> +#define PRLAR0_EL2 PRLAR_EL2
>> +
>> +#define PRBAR_EL2_(n)   PRBAR##n##_EL2
>> +#define PRLAR_EL2_(n)   PRLAR##n##_EL2
>> +
>> +#define GENERATE_WRITE_PR_REG_CASE(num, pr)                                 \
>> +    case num:                                                               \
>> +    {                                                                       \
>> +        WRITE_SYSREG(pr->prbar.bits & ~MPU_REGION_RES0, PRBAR_EL2_(num));   \
>> +        WRITE_SYSREG(pr->prlar.bits & ~MPU_REGION_RES0, PRLAR_EL2_(num));   \
>> +        break;                                                              \
>> +    }
>> +
>> +#define GENERATE_READ_PR_REG_CASE(num, pr)                      \
>> +    case num:                                                   \
>> +    {                                                           \
>> +        pr->prbar.bits = READ_SYSREG(PRBAR_EL2_(num));          \
>> +        pr->prlar.bits = READ_SYSREG(PRLAR_EL2_(num));          \
>> +        break;                                                  \
>> +    }
>> +
>> +/*
>> + * Armv8-R supports direct access and indirect access to the MPU regions through
>> + * registers:
>> + *  - indirect access involves changing the MPU region selector, issuing an isb
>> + *    barrier and accessing the selected region through specific registers
>> + *  - direct access involves accessing specific registers that point to
>> + *    specific MPU regions, without changing the selector, avoiding the use of
>> + *    a barrier.
>> + * For Arm64 the PR{B,L}AR_ELx (for n=0) and PR{B,L}AR<n>_ELx (for n=1..15) are
>> + * used for the direct access to the regions selected by
>> + * PRSELR_EL2.REGION<7:4>:n, so 16 regions can be directly accessed when the
>> + * selector is a multiple of 16, giving access to all the supported memory
>> + * regions.
>> + */
>> +static void prepare_selector(uint8_t *sel)
>> +{
>> +    uint8_t cur_sel = *sel;
>> +
>> +    /*
>> +     * {read,write}_protection_region works using the direct access to the 0..15
>> +     * regions, so in order to save the isb() overhead, change the PRSELR_EL2
>> +     * only when needed, so when the upper 4 bits of the selector will change.
>> +     */
>> +    cur_sel &= 0xF0U;
>> +    if ( READ_SYSREG(PRSELR_EL2) != cur_sel )
>> +    {
>> +        WRITE_SYSREG(cur_sel, PRSELR_EL2);
>> +        isb();
>> +    }
>> +    *sel = *sel & 0xFU;
> This one is different in the original file (*sel &= 0xFU;)
Agree with all of the suggested changes.
>
> The rest looks good to me!
> With the above fixed:
>
> Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
- Ayan
                
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