Re: [PATCH v4 13/29] arm64: convert protection key into vm_flags and pgprot values
From: Dave Martin <Dave.Martin@arm.com>
Date: 2024-08-01 11:01:27
Also in:
kvmarm, linux-fsdevel, linux-mm, linuxppc-dev
On Thu, Aug 01, 2024 at 11:55:02AM +0100, Joey Gouly wrote:
On Thu, Jul 25, 2024 at 04:49:50PM +0100, Dave Martin wrote:quoted
On Fri, May 03, 2024 at 02:01:31PM +0100, Joey Gouly wrote:quoted
Modify arch_calc_vm_prot_bits() and vm_get_page_prot() such that the pkey value is set in the vm_flags and then into the pgprot value. Signed-off-by: Joey Gouly <joey.gouly@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> --- arch/arm64/include/asm/mman.h | 8 +++++++- arch/arm64/mm/mmap.c | 9 +++++++++ 2 files changed, 16 insertions(+), 1 deletion(-)diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h index 5966ee4a6154..ecb2d18dc4d7 100644 --- a/arch/arm64/include/asm/mman.h +++ b/arch/arm64/include/asm/mman.h@@ -7,7 +7,7 @@ #include <uapi/asm/mman.h> static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, - unsigned long pkey __always_unused) + unsigned long pkey) { unsigned long ret = 0;@@ -17,6 +17,12 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, if (system_supports_mte() && (prot & PROT_MTE)) ret |= VM_MTE; +#if defined(CONFIG_ARCH_HAS_PKEYS) + ret |= pkey & 0x1 ? VM_PKEY_BIT0 : 0; + ret |= pkey & 0x2 ? VM_PKEY_BIT1 : 0; + ret |= pkey & 0x4 ? VM_PKEY_BIT2 : 0;Out of interest, is this as bad as it looks or does the compiler turn it into a shift and mask?Yeah, (gcc 13.2) produces good code here (this is do_mprotect_pkey after removing a lot of branching): and w0, w0, #0x7 orr x1, x1, x0, lsl #32
Neat, good ol' gcc! Cheers ---Dave