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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2023-09-25 21:31:48 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-10-19 09:12:47 +0300 |
| commit | bac4cffc7c4a009cf0d16f1785a275e0a7715e8d (patch) | |
| tree | 4d93ecddaecbcf81540ca1c913095ec53ecffcfa /arch/powerpc/mm | |
| parent | 46ebef51fd92f52ba7dca21d3c4332e4127de515 (diff) | |
| download | linux-bac4cffc7c4a009cf0d16f1785a275e0a7715e8d.tar.xz | |
powerpc/32s: Introduce _PAGE_READ and remove _PAGE_USER
On 603 MMU, TLB missed are handled by SW and there are separated
DTLB and ITLB. It is therefore possible to implement execute-only
protection by not loading DTLB when read access is not permitted.
To do that, _PAGE_READ flag is needed but there is no bit available
for it in PTE. On the other hand the only real use of _PAGE_USER is
to implement PAGE_NONE by clearing _PAGE_USER.
As _PAGE_NONE can also be implemented by clearing _PAGE_READ, remove
_PAGE_USER and add _PAGE_READ. Then use the virtual address to know
whether user rights or kernel rights are to be used.
With that change, 603 MMU now honors execute-only protection.
For hash (604) MMU it is more tricky because hash table is common to
load/store and execute. Nevertheless it is still possible to check
whether _PAGE_READ is set before loading hash table for a load/store
access. At least it can't be read unless it is executed first.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/b7702dd5a041ec59055ed2880f4952e94c087a2e.1695659959.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/mm')
| -rw-r--r-- | arch/powerpc/mm/book3s32/hash_low.S | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/arch/powerpc/mm/book3s32/hash_low.S b/arch/powerpc/mm/book3s32/hash_low.S index acb0584c174c..4ed0efd03db5 100644 --- a/arch/powerpc/mm/book3s32/hash_low.S +++ b/arch/powerpc/mm/book3s32/hash_low.S @@ -36,8 +36,9 @@ /* * Load a PTE into the hash table, if possible. - * The address is in r4, and r3 contains an access flag: - * _PAGE_WRITE (0x400) if a write. + * The address is in r4, and r3 contains required access flags: + * - For ISI: _PAGE_PRESENT | _PAGE_EXEC + * - For DSI: _PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE if a write. * r9 contains the SRR1 value, from which we use the MSR_PR bit. * SPRG_THREAD contains the physical address of the current task's thread. * @@ -67,12 +68,16 @@ _GLOBAL(hash_page) lis r0, TASK_SIZE@h /* check if kernel address */ cmplw 0,r4,r0 mfspr r8,SPRN_SPRG_THREAD /* current task's THREAD (phys) */ - ori r3,r3,_PAGE_USER|_PAGE_PRESENT /* test low addresses as user */ lwz r5,PGDIR(r8) /* virt page-table root */ blt+ 112f /* assume user more likely */ lis r5,swapper_pg_dir@ha /* if kernel address, use */ + andi. r0,r9,MSR_PR /* Check usermode */ addi r5,r5,swapper_pg_dir@l /* kernel page table */ - rlwimi r3,r9,32-12,29,29 /* MSR_PR -> _PAGE_USER */ +#ifdef CONFIG_SMP + bne- .Lhash_page_out /* return if usermode */ +#else + bnelr- +#endif 112: tophys(r5, r5) #ifndef CONFIG_PTE_64BIT rlwimi r5,r4,12,20,29 /* insert top 10 bits of address */ @@ -307,12 +312,15 @@ Hash_msk = (((1 << Hash_bits) - 1) * 64) __REF _GLOBAL(create_hpte) /* Convert linux-style PTE (r5) to low word of PPC-style PTE (r8) */ + lis r0, TASK_SIZE@h + rlwinm r5,r5,0,~3 /* Clear PP bits */ + cmplw r4,r0 rlwinm r8,r5,32-9,30,30 /* _PAGE_WRITE -> 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 */ + bge- 1f /* Kernelspace ? Skip */ + ori r5,r5,3 /* Userspace ? PP = 3 */ +1: ori r8,r8,0xe04 /* clear out reserved bits */ 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) */ |