[PATCH 07/14] powerpc/mm: Update _PAGE_KERNEL_RO
From: Aneesh Kumar K.V <hidden>
Date: 2016-03-07 13:40:07
Subsystem:
linux for powerpc (32-bit and 64-bit), ps3 platform support, the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Geoff Levand, Linus Torvalds
PS3 had used PPP bit hack to implement a read only mapping in the kernel area. Since we are bolt mapping the ioremap area, it used the pte flags _PAGE_PRESENT | _PAGE_USER to get a PPP value of 0x3 there by resulting in a read only mapping. This means the area can be accessed by user space, but kernel will never return such an address to user space. Fix this by doing a read only kernel mapping using PPP bits 0b110 This also allows us to do read only kernel mapping for radix in later patches. Signed-off-by: Aneesh Kumar K.V <redacted> --- arch/powerpc/include/asm/book3s/64/hash.h | 4 ++-- arch/powerpc/mm/hash_utils_64.c | 17 +++++++++++------ arch/powerpc/platforms/ps3/spu.c | 2 +- 3 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index 8ccb2970f30f..c2b567456796 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h@@ -115,10 +115,10 @@ #endif /* CONFIG_PPC_MM_SLICES */ /* - * No separate kernel read-only, user access blocked by key + * user access blocked by key */ #define _PAGE_KERNEL_RW (_PAGE_PRIVILEGED | _PAGE_RW | _PAGE_DIRTY) -#define _PAGE_KERNEL_RO _PAGE_KERNEL_RW +#define _PAGE_KERNEL_RO (_PAGE_PRIVILEGED | _PAGE_READ) #define _PAGE_KERNEL_RWX (_PAGE_PRIVILEGED | _PAGE_DIRTY | \ _PAGE_RW | _PAGE_EXEC)
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 630603f74056..c81c08aaff0e 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c@@ -167,14 +167,19 @@ unsigned long htab_convert_pte_flags(unsigned long pteflags) if ((pteflags & _PAGE_EXEC) == 0) rflags |= HPTE_R_N; /* - * PP bits: + * PPP bits: * Linux uses slb key 0 for kernel and 1 for user. - * kernel areas are mapped with PP=00 - * and there is no kernel RO (_PAGE_KERNEL_RO). - * User area is mapped with PP=0x2 for read/write - * or PP=0x3 for read-only (including writeable but clean pages). + * kernel RW areas are mapped with PPP=0b000 + * User area is mapped with PPP=0b010 for read/write + * or PPP=0b011 for read-only (including writeable but clean pages). */ - if (!(pteflags & _PAGE_PRIVILEGED)) { + if (pteflags & _PAGE_PRIVILEGED) { + /* + * Kernel read only mapped with ppp bits 0b110 + */ + if (!(pteflags & _PAGE_WRITE)) + rflags |= (HPTE_R_PP0 | 0x2); + } else { if (pteflags & _PAGE_RWX) rflags |= 0x2; if (!((pteflags & _PAGE_WRITE) && (pteflags & _PAGE_DIRTY)))
diff --git a/arch/powerpc/platforms/ps3/spu.c b/arch/powerpc/platforms/ps3/spu.c
index a0bca05e26b0..5e8a40f9739f 100644
--- a/arch/powerpc/platforms/ps3/spu.c
+++ b/arch/powerpc/platforms/ps3/spu.c@@ -205,7 +205,7 @@ static void spu_unmap(struct spu *spu) static int __init setup_areas(struct spu *spu) { struct table {char* name; unsigned long addr; unsigned long size;}; - static const unsigned long shadow_flags = _PAGE_NO_CACHE | 3; + unsigned long shadow_flags = pgprot_val(pgprot_noncached_wc(PAGE_KERNEL_RO)); spu_pdata(spu)->shadow = __ioremap(spu_pdata(spu)->shadow_addr, sizeof(struct spe_shadow),
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2.5.0