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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2022-01-31 08:17:57 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-02-03 12:56:44 +0100 |
| commit | 4634bf4455fe26f07dabf97c3585c9ccb86353c4 (patch) | |
| tree | e1eb453b1256e1c876e6365c4ca0ff5e36037a1a /arch/powerpc/kernel | |
| parent | powerpc/603: Remove outdated comment (diff) | |
| download | linux-4634bf4455fe26f07dabf97c3585c9ccb86353c4.tar.xz linux-4634bf4455fe26f07dabf97c3585c9ccb86353c4.zip | |
powerpc/603: Clear C bit when PTE is read only
On book3s/32 MMU, PP bits don't offer kernel RO protection,
kernel pages are always RW.
However, on the 603 a page fault is always generated when the
C bit (change bit = dirty bit) is not set.
Enforce kernel RO protection by clearing C bit in TLB miss
handler when the page doesn't have _PAGE_RW flag.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bbb13848ff0100a76ee9ea95118058c30ae95f2c.1643613343.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/head_book3s_32.S | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S index 7e27b44c1d89..d489b965f9a6 100644 --- a/arch/powerpc/kernel/head_book3s_32.S +++ b/arch/powerpc/kernel/head_book3s_32.S @@ -507,7 +507,9 @@ DataLoadTLBMiss: /* Convert linux-style PTE to low word of PPC-style PTE */ rlwinm r1,r0,32-9,30,30 /* _PAGE_RW -> PP msb */ rlwimi r0,r0,32-1,30,30 /* _PAGE_USER -> PP msb */ + rlwimi r1,r0,32-3,24,24 /* _PAGE_RW -> _PAGE_DIRTY */ rlwimi r0,r0,32-1,31,31 /* _PAGE_USER -> PP lsb */ + xori r1,r1,_PAGE_DIRTY /* clear dirty when not rw */ ori r1,r1,0xe04 /* clear out reserved bits */ andc r1,r0,r1 /* PP = user? rw? 1: 3: 0 */ BEGIN_FTR_SECTION |