linux/arch/powerpc/kernel/head_44x.S, branch master

powerpc/44x: Introduce _PAGE_READ and remove _PAGE_USER

2023-10-19T06:12:46Z

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 Signed-off-by: Michael Ellerman Link: https://msgid.link/043e17987b260b99b45094138c6cb2e89e63d499.1695659959.git.christophe.leroy@csgroup.eu

powerpc/nohash: Add _PAGE_WRITE to supplement _PAGE_RW

2023-10-19T06:12:46Z

Several places, _PAGE_RW maps to write permission and don't always imply read. To make it more clear, do as book3s/64 in commit c7d54842deb1 ("powerpc/mm: Use _PAGE_READ to indicate Read access") and use _PAGE_WRITE when more relevant. For the time being _PAGE_WRITE is equivalent to _PAGE_RW but that will change when _PAGE_READ gets added in following patches. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://msgid.link/1f79b88db54d030ada776dc9845e0e88345bfc28.1695659959.git.christophe.leroy@csgroup.eu

powerpc: remove unneeded #include

2023-08-16T13:54:48Z

There is no EXPORT_SYMBOL line there, hence #include is unneeded. Signed-off-by: Masahiro Yamada Signed-off-by: Michael Ellerman Link: https://msgid.link/20230806150954.394189-1-masahiroy@kernel.org

powerpc: allow minimum sized kernel stack frames

2022-12-02T06:54:09Z

This affects only 64-bit ELFv2 kernels, and reduces the minimum asm-created stack frame size from 112 to 32 byte on those kernels. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221127124942.1665522-16-npiggin@gmail.com

powerpc/32: Remove _ENTRY() macro

2022-02-07T10:03:10Z

_ENTRY() is now redundant with _GLOBAL(). Remove it. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/62a35f8dde2bb74c8d0d7a5430cce07a5a3a6fb6.1638273868.git.christophe.leroy@csgroup.eu

powerpc/kuap: Wire-up KUAP on 44x

2021-12-09T11:41:20Z

This adds KUAP support to 44x. This is done by checking the content of SPRN_PID at the time it is read and written into SPRN_MMUCR. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/7d6c3f1978a26feada74b084f651e8cf1e3b3a47.1634627931.git.christophe.leroy@csgroup.eu

powerpc/44x: Activate KUEP at all time

2021-12-09T11:41:17Z

On 44x, KUEP is implemented by clearing SX bit during TLB miss for user pages. The impact is minimal and not worth neither boot time nor build time selection. Activate it at all time. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/2414d662558e7fb27d1ed41c8e47c591d576acac.1634627931.git.christophe.leroy@csgroup.eu

powerpc/booke: Avoid link stack corruption in several places

2021-08-25T03:35:47Z

Use bcl 20,31,+4 instead of bl in order to preserve link stack. See commit c974809a26a1 ("powerpc/vdso: Avoid link stack corruption in __get_datapage()") for details. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/e9fbc285eceb720e6c0e032ef47fe8b05f669b48.1629791751.git.christophe.leroy@csgroup.eu

powerpc: Define swapper_pg_dir[] in C

2021-06-16T14:09:10Z

Don't duplicate swapper_pg_dir[] in each platform's head.S Define it in mm/pgtable.c Define MAX_PTRS_PER_PGD because on book3s/64 PTRS_PER_PGD is not a constant. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/5e3f1b8a4695c33ccc80aa3870e016bef32b85e1.1623063174.git.christophe.leroy@csgroup.eu

powerpc: Define empty_zero_page[] in C

2021-06-16T14:09:10Z

At the time being, empty_zero_page[] is defined in each platform head.S. Define it in mm/mem.c instead, and put it in BSS section instead of the DATA section. Commit 5227cfa71f9e ("arm64: mm: place empty_zero_page in bss") explains why it is interesting to have it in BSS. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/5838caffa269e0957c5a50cc85477876220298b0.1623063174.git.christophe.leroy@csgroup.eu