[PATCH] aarch64: Add FEAT_MPAMv2 system registers

[Alice Carlotti]

On Wed, Jan 14, 2026 at 04:47:40PM +0000, Ezra.Sitorus@arm.com wrote:
> From: Ezra Sitorus <ezra.sitorus@arm.com>
> 
> ---
> This patch adds the MPAMv2 sysregs. 
> Regression tested on aarch64-none-linux-gnu.
> 
> Ezra
> 
>  gas/testsuite/gas/aarch64/sysreg/mpamv2.d | 14 ++++++++++++++
>  gas/testsuite/gas/aarch64/sysreg/mpamv2.s |  5 +++++
>  opcodes/aarch64-sys-regs.def              |  3 +++
>  3 files changed, 22 insertions(+)
>  create mode 100644 gas/testsuite/gas/aarch64/sysreg/mpamv2.d
>  create mode 100644 gas/testsuite/gas/aarch64/sysreg/mpamv2.s
> 
> diff --git a/gas/testsuite/gas/aarch64/sysreg/mpamv2.d b/gas/testsuite/gas/aarch64/sysreg/mpamv2.d
> new file mode 100644
> index 00000000000..fee7d2b9f0e
> --- /dev/null
> +++ b/gas/testsuite/gas/aarch64/sysreg/mpamv2.d
> @@ -0,0 +1,14 @@
> +#as: -march=armv9.4-a -I$srcdir/$subdir
> +#objdump: -dr
> +
> +.*:     file format .*
> +
> +Disassembly of section \.text:
> +
> +0+ <.*>:
> +.*:	d51da540 	msr	mpamctl_el1, x0
> +.*:	d53da540 	mrs	x0, mpamctl_el1
> +.*:	d518a540 	msr	mpamctl_el2, x0
> +.*:	d538a540 	mrs	x0, mpamctl_el2
> +.*:	d51ea540 	msr	mpamctl_el3, x0
> +.*:	d53ea540 	mrs	x0, mpamctl_el3
> diff --git a/gas/testsuite/gas/aarch64/sysreg/mpamv2.s b/gas/testsuite/gas/aarch64/sysreg/mpamv2.s
> new file mode 100644
> index 00000000000..882ec40c5c5
> --- /dev/null
> +++ b/gas/testsuite/gas/aarch64/sysreg/mpamv2.s
> @@ -0,0 +1,5 @@
> +.include "sysreg-test-utils.inc"
> +
> +	rw_sys_reg mpamctl_el1
> +	rw_sys_reg mpamctl_el2
> +	rw_sys_reg mpamctl_el3
> diff --git a/opcodes/aarch64-sys-regs.def b/opcodes/aarch64-sys-regs.def
> index 818c2adbec7..f57e02cecdf 100644
> --- a/opcodes/aarch64-sys-regs.def
> +++ b/opcodes/aarch64-sys-regs.def
> @@ -922,6 +922,9 @@
>    SYSREG ("mpambwcap_el2",	CPENC (3,4,10,5,6),	0,		AARCH64_FEATURE (V9_3A)) /* MPAM_PE_BW_CTRL */
>    SYSREG ("mpambwidr_el1",	CPENC (3,0,10,4,5),	F_REG_READ,	AARCH64_FEATURE (V9_3A)) /* MPAM_PE_BW_CTRL */
>    SYSREG ("mpambwsm_el1",	CPENC (3,0,10,5,7),	0,		AARCH64_FEATURES (2, SME, V9_3A)) /* SME && MPAM_PE_BW_CTRL */
> +  SYSREG ("mpamctl_el1",	CPENC (3,5,10,5,2),	0,		AARCH64_FEATURE (V9_4A)) /* MPAMV2 */
> +  SYSREG ("mpamctl_el2",	CPENC (3,0,10,5,2),	0,		AARCH64_FEATURE (V9_4A)) /* MPAMV2 */
> +  SYSREG ("mpamctl_el3",	CPENC (3,6,10,5,2),	0,		AARCH64_FEATURE (V9_4A)) /* MPAMV2 */

This is missing mpamctl_el12.

Also, we've agreed (with LLVM developers) to add a +mpamv2 flag to gate the
system instructions, so that should also be used as the feature constraint here
(and for the FEAT_MPAMv2_VID system instructions and sysregs as well).

Thanks,
Alice

>    SYSREG ("mpamhcr_el2",	CPENC (3,4,10,4,0),	0,		AARCH64_FEATURE (V8_2A)) /* MPAM */
>    SYSREG ("mpamidr_el1",	CPENC (3,0,10,4,4),	F_REG_READ,	AARCH64_FEATURE (V8_2A)) /* MPAM */
>    SYSREG ("mpamsm_el1",		CPENC (3,0,10,5,3),	0,		AARCH64_FEATURES (2, SME, V8_2A)) /* SME && MPAM */
> -- 
> 2.43.0
>