Re: [RFC PATCH 02/11] arm64: Move arch-specific prctls out of core code

From: Will Deacon
Date: Mon May 21 2018 - 13:35:07 EST


On Mon, May 14, 2018 at 06:14:18PM +0100, Dave Martin wrote:
> This patch moves the arm64-specific prctl call implementations out
> of core code and removes redundant boilerplate associated with
> them.
>
> No functional change.
>
> Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> ---
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/processor.h | 4 ----
> arch/arm64/kernel/sys.c | 15 +++++++++++++++
> kernel/sys.c | 12 ------------
> 4 files changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index eb2cf49..6b706af 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -123,6 +123,7 @@ config ARM64
> select HAVE_PERF_EVENTS
> select HAVE_PERF_REGS
> select HAVE_PERF_USER_STACK_DUMP
> + select HAVE_PRCTL_ARCH
> select HAVE_REGS_AND_STACK_ACCESS_API
> select HAVE_RCU_TABLE_FREE
> select HAVE_SYSCALL_TRACEPOINTS
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index 7675989..b1d262f 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -244,9 +244,5 @@ void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused);
> void cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused);
> void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused);
>
> -/* Userspace interface for PR_SVE_{SET,GET}_VL prctl()s: */
> -#define SVE_SET_VL(arg) sve_set_current_vl(arg)
> -#define SVE_GET_VL() sve_get_current_vl()
> -
> #endif /* __ASSEMBLY__ */
> #endif /* __ASM_PROCESSOR_H */
> diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
> index 72981ba..597ff35 100644
> --- a/arch/arm64/kernel/sys.c
> +++ b/arch/arm64/kernel/sys.c
> @@ -22,10 +22,12 @@
> #include <linux/fs.h>
> #include <linux/mm.h>
> #include <linux/export.h>
> +#include <linux/prctl.h>
> #include <linux/sched.h>
> #include <linux/slab.h>
> #include <linux/syscalls.h>
> #include <asm/cpufeature.h>
> +#include <asm/fpsimd.h>
>
> asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
> unsigned long prot, unsigned long flags,
> @@ -45,6 +47,19 @@ SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
> return sys_personality(personality);
> }
>
> +int prctl_arch(int option, unsigned long arg2, unsigned long arg3,
> + unsigned long arg4, unsigned long arg5)
> +{
> + switch (option) {
> + case PR_SVE_SET_VL:
> + return sve_set_current_vl(arg2);
> + case PR_SVE_GET_VL:
> + return sve_get_current_vl();
> + default:
> + return -EINVAL;
> + }
> +}

If we think this might grow, then it might be worth adding a prctl.c to
collect these together. Anyhow:

Acked-by: Will Deacon <will.deacon@xxxxxxx>

Will