diff options
| author |   Christophe Leroy <christophe.leroy@c-s.fr> | 2019-03-11 08:30:36 +0000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2019-04-21 23:11:46 +1000 |
| commit | f342adca3afc84c4ef648352440ed6331518d72d (patch) | |
| tree | 95f2708cfa6ece80e9f7f9cb9824fc7786907589 /arch/powerpc/mm | |
| parent | powerpc/32s: Implement Kernel Userspace Execution Prevention. (diff) | |
| download | linux-dev-f342adca3afc84c4ef648352440ed6331518d72d.tar.xz linux-dev-f342adca3afc84c4ef648352440ed6331518d72d.zip | |
powerpc/32s: Prepare Kernel Userspace Access Protection
This patch prepares Kernel Userspace Access Protection for
book3s/32.
Due to limitations of the processor page protection capabilities,
the protection is only against writing. read protection cannot be
achieved using page protection.
book3s/32 provides the following values for PP bits:
PP00 provides RW for Key 0 and NA for Key 1
PP01 provides RW for Key 0 and RO for Key 1
PP10 provides RW for all
PP11 provides RO for all
Today PP10 is used for RW pages and PP11 for RO pages, and user
segment register's Kp and Ks are set to 1. This patch modifies
page protection to use PP01 for RW pages and sets user segment
registers to Kp 0 and Ks 0.
This will allow to setup Userspace write access protection by
settng Ks to 1 in the following patch.
Kernel space segment registers remain unchanged.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/mm')
| -rw-r--r-- | arch/powerpc/mm/hash_low_32.S | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/powerpc/mm/hash_low_32.S b/arch/powerpc/mm/hash_low_32.S index a6c491f18a04..e27792d0b744 100644 --- a/arch/powerpc/mm/hash_low_32.S +++ b/arch/powerpc/mm/hash_low_32.S @@ -309,13 +309,13 @@ Hash_msk = (((1 << Hash_bits) - 1) * 64) _GLOBAL(create_hpte) /* Convert linux-style PTE (r5) to low word of PPC-style PTE (r8) */ - rlwinm r8,r5,32-10,31,31 /* _PAGE_RW -> PP lsb */ - rlwinm r0,r5,32-7,31,31 /* _PAGE_DIRTY -> PP lsb */ + rlwinm r8,r5,32-9,30,30 /* _PAGE_RW -> PP msb */ + rlwinm r0,r5,32-6,30,30 /* _PAGE_DIRTY -> PP msb */ and r8,r8,r0 /* writable if _RW & _DIRTY */ rlwimi r5,r5,32-1,30,30 /* _PAGE_USER -> PP msb */ rlwimi r5,r5,32-2,31,31 /* _PAGE_USER -> PP lsb */ ori r8,r8,0xe04 /* clear out reserved bits */ - andc r8,r5,r8 /* PP = user? (rw&dirty? 2: 3): 0 */ + andc r8,r5,r8 /* PP = user? (rw&dirty? 1: 3): 0 */ BEGIN_FTR_SECTION rlwinm r8,r8,0,~_PAGE_COHERENT /* clear M (coherence not required) */ END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT) |