| Message ID | bbb13848ff0100a76ee9ea95118058c30ae95f2c.1643613343.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | powerpc/603: Clear C bit when PTE is read only | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 7 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 24 jobs. |
On Mon, 31 Jan 2022 07:17:57 +0000, Christophe Leroy wrote: > 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. > > [...] Applied to powerpc/next. [1/1] powerpc/603: Clear C bit when PTE is read only https://git.kernel.org/powerpc/c/4634bf4455fe26f07dabf97c3585c9ccb86353c4 cheers
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S index 7f4f3a52b730..6c739beb938c 100644 --- a/arch/powerpc/kernel/head_book3s_32.S +++ b/arch/powerpc/kernel/head_book3s_32.S @@ -504,7 +504,9 @@ 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
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> --- arch/powerpc/kernel/head_book3s_32.S | 2 ++ 1 file changed, 2 insertions(+)