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author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2023-09-25 20:31:45 +0200 |
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committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-10-19 17:12:46 +1100 |
commit | 93820bfeefc4a125a6cedd1ee1a956eeb3eb2580 (patch) | |
tree | d6f5222c3333f431cd060c33ab70d446a71c40e6 /arch/powerpc/kernel | |
parent | 48cf93bb168d506a8278a6fb25c2f88c1c93ce6e (diff) | |
download | lwn-93820bfeefc4a125a6cedd1ee1a956eeb3eb2580.tar.gz lwn-93820bfeefc4a125a6cedd1ee1a956eeb3eb2580.zip |
powerpc/44x: Introduce _PAGE_READ and remove _PAGE_USER
44x MMU has 6 page protection bits:
- R, W, X for supervisor
- R, W, X for user
It means that it can support X without R.
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. In order to insert bits in
one go during TLB miss, move _PAGE_ACCESSED and put _PAGE_READ
just after _PAGE_DIRTY so that _PAGE_DIRTY is copied into SW and
_PAGE_READ into SR at once.
With that change, 44x now also honors execute-only protection.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/043e17987b260b99b45094138c6cb2e89e63d499.1695659959.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/kernel')
-rw-r--r-- | arch/powerpc/kernel/head_44x.S | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S index 858dabf84432..25642e802ed3 100644 --- a/arch/powerpc/kernel/head_44x.S +++ b/arch/powerpc/kernel/head_44x.S @@ -314,8 +314,8 @@ interrupt_base: * kernel page tables. */ lis r11, PAGE_OFFSET@h - cmplw r10, r11 - blt+ 3f + cmplw cr7, r10, r11 + blt+ cr7, 3f lis r11, swapper_pg_dir@h ori r11, r11, swapper_pg_dir@l @@ -355,7 +355,7 @@ interrupt_base: * place or can we save a couple of instructions here ? */ mfspr r12,SPRN_ESR - li r13,_PAGE_PRESENT|_PAGE_ACCESSED + li r13,_PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_READ rlwimi r13,r12,10,30,30 /* Load the PTE */ @@ -428,8 +428,8 @@ interrupt_base: * kernel page tables. */ lis r11, PAGE_OFFSET@h - cmplw r10, r11 - blt+ 3f + cmplw cr7, r10, r11 + blt+ cr7, 3f lis r11, swapper_pg_dir@h ori r11, r11, swapper_pg_dir@l @@ -515,6 +515,7 @@ interrupt_base: * r11 - PTE high word value * r12 - PTE low word value * r13 - TLB index + * cr7 - Result of comparison with PAGE_OFFSET * MMUCR - loaded with proper value when we get here * Upon exit, we reload everything and RFI. */ @@ -533,11 +534,10 @@ finish_tlb_load_44x: tlbwe r10,r13,PPC44x_TLB_PAGEID /* Write PAGEID */ /* And WS 2 */ - li r10,0xf85 /* Mask to apply from PTE */ - rlwimi r10,r12,29,30,30 /* DIRTY -> SW position */ + li r10,0xf84 /* Mask to apply from PTE */ + rlwimi r10,r12,29,30,31 /* DIRTY,READ -> SW,SR position */ and r11,r12,r10 /* Mask PTE bits to keep */ - andi. r10,r12,_PAGE_USER /* User page ? */ - beq 1f /* nope, leave U bits empty */ + bge cr7,1f /* User page ? no, leave U bits empty */ rlwimi r11,r11,3,26,28 /* yes, copy S bits to U */ rlwinm r11,r11,0,~PPC44x_TLB_SX /* Clear SX if User page */ 1: tlbwe r11,r13,PPC44x_TLB_ATTRIB /* Write ATTRIB */ @@ -568,8 +568,8 @@ finish_tlb_load_44x: * kernel page tables. */ lis r11,PAGE_OFFSET@h - cmplw cr0,r10,r11 - blt+ 3f + cmplw cr7,r10,r11 + blt+ cr7,3f lis r11,swapper_pg_dir@h ori r11,r11, swapper_pg_dir@l li r12,0 /* MMUCR = 0 */ @@ -599,7 +599,7 @@ finish_tlb_load_44x: * place or can we save a couple of instructions here ? */ mfspr r12,SPRN_ESR - li r13,_PAGE_PRESENT|_PAGE_ACCESSED + li r13,_PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_READ rlwimi r13,r12,10,30,30 /* Load the PTE */ @@ -669,8 +669,8 @@ finish_tlb_load_44x: * kernel page tables. */ lis r11,PAGE_OFFSET@h - cmplw cr0,r10,r11 - blt+ 3f + cmplw cr7,r10,r11 + blt+ cr7,3f lis r11,swapper_pg_dir@h ori r11,r11, swapper_pg_dir@l li r12,0 /* MMUCR = 0 */ @@ -744,6 +744,7 @@ finish_tlb_load_44x: * r11 - PTE high word value * r12 - PTE low word value * r13 - free to use + * cr7 - Result of comparison with PAGE_OFFSET * MMUCR - loaded with proper value when we get here * Upon exit, we reload everything and RFI. */ @@ -753,11 +754,10 @@ finish_tlb_load_47x: tlbwe r11,r13,1 /* And make up word 2 */ - li r10,0xf85 /* Mask to apply from PTE */ - rlwimi r10,r12,29,30,30 /* DIRTY -> SW position */ + li r10,0xf84 /* Mask to apply from PTE */ + rlwimi r10,r12,29,30,31 /* DIRTY,READ -> SW,SR position */ and r11,r12,r10 /* Mask PTE bits to keep */ - andi. r10,r12,_PAGE_USER /* User page ? */ - beq 1f /* nope, leave U bits empty */ + bge cr7,1f /* User page ? no, leave U bits empty */ rlwimi r11,r11,3,26,28 /* yes, copy S bits to U */ rlwinm r11,r11,0,~PPC47x_TLB2_SX /* Clear SX if User page */ 1: tlbwe r11,r13,2 |