[patch 5/6] powerpc: Add Strong Access Ordering
From: <hidden>
Date: 2008-06-18 22:35:59
Also in:
linux-mm
Allow an application to enable Strong Access Ordering on specific pages of memory on Power 7 hardware. Currently, power has a weaker memory model than x86. Implementing a stronger memory model allows an emulator to more efficiently translate x86 code into power code, resulting in faster code execution. On Power 7 hardware, storing 0b1110 in the WIMG bits of the hpte enables strong access ordering mode for the memory page. This patchset allows a user to specify which pages are thus enabled by passing a new protection bit through mmap() and mprotect(). I have tentatively defined this bit, PROT_SAO, as 0x10. Signed-off-by: Dave Kleikamp <redacted> --- arch/powerpc/kernel/syscalls.c | 3 +++ include/asm-powerpc/mman.h | 28 ++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+) Index: linux-2.6.26-rc5/arch/powerpc/kernel/syscalls.c ===================================================================
--- linux-2.6.26-rc5.orig/arch/powerpc/kernel/syscalls.c
+++ linux-2.6.26-rc5/arch/powerpc/kernel/syscalls.c@@ -143,6 +143,9 @@ static inline unsigned long do_mmap2(uns struct file * file = NULL; unsigned long ret = -EINVAL; + if (!arch_validate_prot(prot)) + goto out; + if (shift) { if (off & ((1 << shift) - 1)) goto out;
Index: linux-2.6.26-rc5/include/asm-powerpc/mman.h ===================================================================
--- linux-2.6.26-rc5.orig/include/asm-powerpc/mman.h
+++ linux-2.6.26-rc5/include/asm-powerpc/mman.h@@ -1,7 +1,9 @@ #ifndef _ASM_POWERPC_MMAN_H #define _ASM_POWERPC_MMAN_H +#include <asm/cputable.h> #include <asm-generic/mman.h> +#include <linux/mm.h> /* * This program is free software; you can redistribute it and/or
@@ -26,4 +28,30 @@ #define MAP_POPULATE 0x8000 /* populate (prefault) pagetables */ #define MAP_NONBLOCK 0x10000 /* do not block on IO */ +/* + * This file is included by linux/mman.h, so we can't use cacl_vm_prot_bits() + * here. How important is the optimization? + */ +static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot) +{ + return (prot & PROT_SAO) ? VM_SAO : 0; +} +#define arch_calc_vm_prot_bits(prot) arch_calc_vm_prot_bits(prot) + +static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags) +{ + return (vm_flags & VM_SAO) ? __pgprot(_PAGE_SAO) : 0; +} +#define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags) + +static inline int arch_validate_prot(unsigned long prot) +{ + if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_SAO)) + return 0; + if ((prot & PROT_SAO) && !cpu_has_feature(CPU_FTR_SAO)) + return 0; + return 1; +} +#define arch_validate_prot(prot) arch_validate_prot(prot) + #endif /* _ASM_POWERPC_MMAN_H */
--