- 26 May, 2020 38 commits
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Michael Ellerman authored
Merge Christophe's large series to use huge pages for the linear mapping on 8xx. From his cover letter: The main purpose of this big series is to: - reorganise huge page handling to avoid using mm_slices. - use huge pages to map kernel memory on the 8xx. The 8xx supports 4 page sizes: 4k, 16k, 512k and 8M. It uses 2 Level page tables, PGD having 1024 entries, each entry covering 4M address space. Then each page table has 1024 entries. At the time being, page sizes are managed in PGD entries, implying the use of mm_slices as it can't mix several pages of the same size in one page table. The first purpose of this series is to reorganise things so that standard page tables can also handle 512k pages. This is done by adding a new _PAGE_HUGE flag which will be copied into the Level 1 entry in the TLB miss handler. That done, we have 2 types of pages: - PGD entries to regular page tables handling 4k/16k and 512k pages - PGD entries to hugepd tables handling 8M pages. There is no need to mix 8M pages with other sizes, because a 8M page will use more than what a single PGD covers. Then comes the second purpose of this series. At the time being, the 8xx has implemented special handling in the TLB miss handlers in order to transparently map kernel linear address space and the IMMR using huge pages by building the TLB entries in assembly at the time of the exception. As mm_slices is only for user space pages, and also because it would anyway not be convenient to slice kernel address space, it was not possible to use huge pages for kernel address space. But after step one of the series, it is now more flexible to use huge pages. This series drop all assembly 'just in time' handling of huge pages and use huge pages in page tables instead. Once the above is done, then comes icing on the cake: - Use huge pages for KASAN shadow mapping - Allow pinned TLBs with strict kernel rwx - Allow pinned TLBs with debug pagealloc Then, last but not least, those modifications for the 8xx allows the following improvement on book3s/32: - Mapping KASAN shadow with BATs - Allowing BATs with debug pagealloc All this allows to considerably simplify TLB miss handlers and associated initialisation. The overhead of reading page tables is negligible compared to the reduction of the miss handlers. While we were at touching pte_update(), some cleanup was done there too. Tested widely on 8xx and 832x. Boot tested on QEMU MAC99.
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Christophe Leroy authored
Implement a kasan_init_region() dedicated to book3s/32 that allocates KASAN regions using BATs. Signed-off-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/709e821602b48a1d7c211a9b156da26db98c3e9d.1589866984.git.christophe.leroy@csgroup.eu
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Christophe Leroy authored
DEBUG_PAGEALLOC only manages RW data. Text and RO data can still be mapped with BATs. In order to map with BATs, also enforce data alignment. Set by default to 256M which is a good compromise for keeping enough BATs for also KASAN and IMMR. Signed-off-by:
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Christophe Leroy authored
Implement a kasan_init_region() dedicated to 8xx that allocates KASAN regions using huge pages. Signed-off-by:
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Christophe Leroy authored
DEBUG_PAGEALLOC only manages RW data. Text and RO data can still be mapped with hugepages and pinned TLB. In order to map with hugepages, also enforce a 512kB data alignment minimum. That's a trade-off between size of speed, taking into account that DEBUG_PAGEALLOC is a debug option. Anyway the alignment is still tunable. We also allow tuning of alignment for book3s to limit the complexity of the test in Kconfig that will anyway disappear in the following patches once DEBUG_PAGEALLOC is handled together with BATs. Signed-off-by:
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Christophe Leroy authored
Pinned TLB are 8M. Now that there is no strict boundary anymore between text and RO data, it is possible to use 8M pinned executable TLB that covers both text and RO data. When PIN_TLB_DATA or PIN_TLB_TEXT is selected, enforce 8M RW data alignment and allow STRICT_KERNEL_RWX. Signed-off-by:
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Christophe Leroy authored
Map linear memory space with 512k and 8M pages whenever possible. Three mappings are performed: - One for kernel text - One for RO data - One for the rest Separating the mappings is done to be able to update the protection later when using STRICT_KERNEL_RWX. The ITLB miss handler now need to also handle huge TLBs unless kernel text in pinned. Signed-off-by:
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Christophe Leroy authored
Map the IMMR area with a single 512k huge page. Signed-off-by:
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Christophe Leroy authored
Add a function to early map kernel memory using huge pages. For 512k pages, just use standard page table and map in using 512k pages. For 8M pages, create a hugepd table and populate the two PGD entries with it. This function can only be used to create page tables at startup. Once the regular SLAB allocation functions replace memblock functions, this function cannot allocate new pages anymore. However it can still update existing mappings with new protections. hugepd_none() macro is moved into asm/hugetlb.h to be usable outside of mm/hugetlbpage.c early_pte_alloc_kernel() is made visible. _PAGE_HUGE flag is now displayed by ptdump. Signed-off-by:
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Christophe Leroy authored
Now that linear and IMMR dedicated TLB handling is gone, kernel boundary address comparison is similar in ITLB miss handler and in DTLB miss handler. Create a macro named compare_to_kernel_boundary. When TASK_SIZE is strictly below 0x80000000 and PAGE_OFFSET is above 0x80000000, it is enough to compare to 0x8000000, and this can be done with a single instruction. Using not. instruction, we get to use 'blt' conditional branch as when doing a regular comparison: 0x00000000 <= addr <= 0x7fffffff ==> 0xffffffff >= NOT(addr) >= 0x80000000 The above test corresponds to a 'blt' Otherwise, do a regular comparison using two instructions. Signed-off-by:
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Christophe Leroy authored
Similar to PPC64, accept to map RO data as ROX as a trade off between between security and memory usage. Having RO data executable is not a high risk as RO data can't be modified to forge an exploit. Signed-off-by:
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Christophe Leroy authored
Now that space have been freed next to the DTLB miss handler, it's associated DTLB perf handling can be brought back in the same place. Signed-off-by:
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Christophe Leroy authored
The code to setup linear and IMMR mapping via huge TLB entries is not called anymore. Remove it. Also remove the handling of removed code exits in the perf driver. Signed-off-by:
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Christophe Leroy authored
Up to now, linear and IMMR mappings are managed via huge TLB entries through specific code directly in TLB miss handlers. This implies some patching of the TLB miss handlers at startup, and a lot of dedicated code. Remove all this specific dedicated code. For now we are back to normal handling via standard 4k pages. In the next patches, linear memory mapping and IMMR mapping will be managed through huge pages. Signed-off-by:
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Christophe Leroy authored
At startup, map 32 Mbytes of memory through 4 pages of 8M, and PIN them inconditionnaly. They need to be pinned because KASAN is using page tables early and the TLBs might be dynamically replaced otherwise. Remove RSV4I flag after installing mappings unless CONFIG_PIN_TLB_XXXX is selected. Signed-off-by:
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Christophe Leroy authored
Only early debug requires IMMR to be mapped early. No need to set it up and pin it in assembly. Map it through page tables at udbg init when necessary. If CONFIG_PIN_TLB_IMMR is selected, pin it once we don't need the 32 Mb pinned RAM anymore. Signed-off-by:
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Christophe Leroy authored
Pinned TLBs cannot be modified when the MMU is enabled. Create a function to rewrite the pinned TLB entries with MMU off. To set pinned TLB, we have to turn off MMU, disable pinning, do a TLB flush (Either with tlbie and tlbia) then reprogam the TLB entries, enable pinning and turn on MMU. If using tlbie, it cleared entries in both instruction and data TLB regardless whether pinning is disabled or not. If using tlbia, it clears all entries of the TLB which has disabled pinning. To make it easy, just clear all entries in both TLBs, and reprogram them. The function takes two arguments, the top of the memory to consider and whether data is RO under _sinittext. When DEBUG_PAGEALLOC is set, the top is the end of kernel rodata. Otherwise, that's the top of physical RAM. Everything below _sinittext is set RX, over _sinittext that's RW. Signed-off-by:
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Christophe Leroy authored
PPC_PIN_TLB options are dedicated to the 8xx, move them into the 8xx Kconfig. While we are at it, add some text to explain what it does. Signed-off-by:
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Christophe Leroy authored
As the 8xx now manages 512k pages in standard page tables, it doesn't need CONFIG_PPC_MM_SLICES anymore. Don't select it anymore and remove all related code. Signed-off-by:
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Christophe Leroy authored
512k pages are now standard pages, so only 8M pages are hugepte. No more handling of normal page tables through hugepd allocation and freeing, and hugepte helpers can also be simplified. Signed-off-by:
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Christophe Leroy authored
At the time being, 512k huge pages are handled through hugepd page tables. The PMD entry is flagged as a hugepd pointer and it means that only 512k hugepages can be managed in that 4M block. However, the hugepd table has the same size as a normal page table, and 512k entries can therefore be nested with normal pages. On the 8xx, TLB loading is performed by software and allthough the page tables are organised to match the L1 and L2 level defined by the HW, all TLB entries have both L1 and L2 independent entries. It means that even if two TLB entries are associated with the same PMD entry, they can be loaded with different values in L1 part. The L1 entry contains the page size (PS field): - 00 for 4k and 16 pages - 01 for 512k pages - 11 for 8M pages By adding a flag for hugepages in the PTE (_PAGE_HUGE) and copying it into the lower bit of PS, we can then manage 512k pages with normal page tables: - PMD entry has PS=11 for 8M pages - PMD entry has PS=00 for other pages. As a PMD entry covers 4M areas, a PMD will either point to a hugepd table having a single entry to an 8M page, or the PMD will point to a standard page table which will have either entries to 4k or 16k or 512k pages. For 512k pages, as the L1 entry will not know it is a 512k page before the PTE is read, there will be 128 entries in the PTE as if it was 4k pages. But when loading the TLB, it will be flagged as a 512k page. Note that we can't use pmd_ptr() in asm/nohash/32/pgtable.h because it is not defined yet. In ITLB miss, we keep the possibility to opt it out as when kernel text is pinned and no user hugepages are used, we can save several instruction by not using r11. In DTLB miss, that's just one instruction so it's not worth bothering with it. Signed-off-by:
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Christophe Leroy authored
Prepare ITLB handler to handle _PAGE_HUGE when CONFIG_HUGETLBFS is enabled. This means that the L1 entry has to be kept in r11 until L2 entry is read, in order to insert _PAGE_HUGE into it. Also move pgd_offset helpers before pte_update() as they will be needed there in next patch. Signed-off-by:
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Christophe Leroy authored
CONFIG_8xx_COPYBACK was there to help disabling copyback cache mode for debuging hardware. But nobody will design new boards with 8xx now. All 8xx platforms select it, so make it the default and remove the option. Also remove the Mx_RESETVAL values which are pretty useless and hide the real value while reading code. Signed-off-by:
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Christophe Leroy authored
Commit 55c8fc3f ("powerpc/8xx: reintroduce 16K pages with HW assistance") redefined pte_t as a struct of 4 pte_basic_t, because in 16K pages mode there are four identical entries in the page table. But hugepd entries for 8M pages require only one entry of size pte_basic_t. So there is no point in creating a cache for 4 entries page tables. Calculate PTE_T_ORDER using the size of pte_basic_t instead of pte_t. Define specific huge_pte helpers (set_huge_pte_at(), huge_pte_clear(), huge_ptep_set_wrprotect()) to write the pte in a single entry instead of using set_pte_at() which writes 4 identical entries in 16k pages mode. Also make sure that __ptep_set_access_flags() properly handle the huge_pte case. Define set_pte_filter() inline otherwise GCC doesn't inline it anymore because it is now used twice, and that gives a pretty suboptimal code because of pte_t being a struct of 4 entries. Those functions are also used for 512k pages which only require one entry as well allthough replicating it four times was harmless as 512k pages entries are spread every 128 bytes in the table. Signed-off-by:
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Christophe Leroy authored
pte_update() is a bit special for the 8xx. At the time being, that's an #ifdef inside the nohash/32 pte_update(). As we are going to make it even more special in the coming patches, create a dedicated version for pte_update() for 8xx. Signed-off-by:
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Christophe Leroy authored
PPC64 takes 3 additional parameters compared to PPC32: - mm - address - huge These 3 parameters will be needed in order to perform different action depending on the page size on the 8xx. Make pte_update() prototype identical for PPC32 and PPC64. This allows dropping an #ifdef in huge_ptep_get_and_clear(). Signed-off-by:
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Christophe Leroy authored
On PPC32, __ptep_test_and_clear_young() takes the mm->context.id In preparation of standardising pte_update() params between PPC32 and PPC64, __ptep_test_and_clear_young() need mm instead of mm->context.id Replace context param by mm. Signed-off-by:
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Christophe Leroy authored
When CONFIG_PTE_64BIT is set, pte_update() operates on 'unsigned long long' When CONFIG_PTE_64BIT is not set, pte_update() operates on 'unsigned long' In asm/page.h, we have pte_basic_t which is 'unsigned long long' when CONFIG_PTE_64BIT is set and 'unsigned long' otherwise. Refactor pte_update() using pte_basic_t. While we are at it, drop the comment on 44x which is not applicable to book3s version of pte_update(). Signed-off-by:
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Christophe Leroy authored
When CONFIG_PTE_64BIT is set, pte_update() operates on 'unsigned long long' When CONFIG_PTE_64BIT is not set, pte_update() operates on 'unsigned long' In asm/page.h, we have pte_basic_t which is 'unsigned long long' when CONFIG_PTE_64BIT is set and 'unsigned long' otherwise. Refactor pte_update() using pte_basic_t. Signed-off-by:
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Christophe Leroy authored
Only 40x still uses PTE_ATOMIC_UPDATES. 40x cannot not select CONFIG_PTE64_BIT. Drop handling of PTE_ATOMIC_UPDATES: - In nohash/64 - In nohash/32 for CONFIG_PTE_64BIT Keep PTE_ATOMIC_UPDATES only for nohash/32 for !CONFIG_PTE_64BIT Signed-off-by:
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Christophe Leroy authored
Setting init mem to NX shall depend on sinittext being mapped by block, not on stext being mapped by block. Setting text and rodata to RO shall depend on stext being mapped by block, not on sinittext being mapped by block. Fixes: 63b2bc61 ("powerpc/mm/32s: Use BATs for STRICT_KERNEL_RWX") Cc: stable@vger.kernel.org Signed-off-by:
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Christophe Leroy authored
Allocate static page tables for the fixmap area. This allows setting mappings through page tables before memblock is ready. That's needed to use early_ioremap() early and to use standard page mappings with fixmap. Signed-off-by:
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Christophe Leroy authored
Mapping RO data as ROX is not an issue since that data cannot be modified to introduce an exploit. PPC64 accepts to have RO data mapped ROX, as a trade off between kernel size and strictness of protection. On PPC32, kernel size is even more critical as amount of memory is usually small. Depending on the number of available IBATs, the last IBATs might overflow the end of text. Only warn if it crosses the end of RO data. Signed-off-by:
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Christophe Leroy authored
The 8xx is about to map kernel linear space and IMMR using huge pages. In order to display those pages properly, ptdump needs to handle hugepd tables at PGD level. For the time being do it only at PGD level. Further patches may add handling of hugepd tables at lower level for other platforms when needed in the future. Signed-off-by:
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Christophe Leroy authored
In order to properly display information regardless of the page size, it is necessary to take into account real page size. Fixes: cabe8138 ("powerpc: dump as a single line areas mapping a single physical page.") Cc: stable@vger.kernel.org Signed-off-by:
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Christophe Leroy authored
Display BAT flags the same way as page flags: rwx and wimg Signed-off-by:
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Christophe Leroy authored
Display the size of areas mapped with BATs. For that, the size display for pages is refactorised. Signed-off-by:
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Christophe Leroy authored
For platforms using shared.c (4xx, Book3e, Book3s/32), also handle the _PAGE_COHERENT flag which corresponds to the M bit of the WIMG flags. Signed-off-by:
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- 20 May, 2020 2 commits
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Christophe Leroy authored
In order to alloc sub-arches to alloc KASAN regions using optimised methods (Huge pages on 8xx, BATs on BOOK3S, ...), declare kasan_init_region() weak. Also make kasan_init_shadow_page_tables() accessible from outside, so that it can be called from the specific kasan_init_region() functions if needed. And populate remaining KASAN address space only once performed the region mapping, to allow 8xx to allocate hugepd instead of standard page tables for mapping via 8M hugepages. Signed-off-by:
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Christophe Leroy authored
kasan_remap_early_shadow_ro() and kasan_unmap_early_shadow_vmalloc() are both updating the early shadow mapping: the first one sets the mapping read-only while the other clears the mapping. Refactor and create kasan_update_early_region() Signed-off-by:
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