kernel.git/arch/mips/mm, branch linux-4.1.y

MIPS: mm: fixed mappings: correct initialisation

2018-05-23T01:36:28Z

[ Upstream commit 71eb989ab5a110df8bcbb9609bacde73feacbedd ] fixrange_init operates at PMD-granularity and expects the addresses to be PMD-size aligned, but currently that might not be the case for PKMAP_BASE unless it is defined properly, so ensure a correct alignment is used before passing the address to fixrange_init. fixed mappings: only align the start address that is passed to fixrange_init rather than the value before adding the size, as we may end up with uninitialised upper part of the range. Signed-off-by: Marcin Nowakowski Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/15948/ Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

MIPS: IP22: Reformat inline assembler code to modern standards.

2018-01-17T17:25:48Z

[ Upstream commit f9f1c8db1c37253805eaa32265e1e1af3ae7d0a4 ] Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

MIPS: microMIPS: Fix incorrect mask in insn_table_MM

2017-12-07T02:20:01Z

[ Upstream commit 77238e76b9156d28d86c1e31c00ed2960df0e4de ] It seems that this is a typo error and the proper bit masking is "RT | RS" instead of "RS | RS". This issue was detected with the help of Coccinelle. Fixes: d6b3314b49e1 ("MIPS: uasm: Add lh uam instruction") Reported-by: Julia Lawall Signed-off-by: Gustavo A. R. Silva Reviewed-by: James Hogan Cc: # 3.16+ Patchwork: https://patchwork.linux-mips.org/patch/17551/ Signed-off-by: James Hogan Signed-off-by: Sasha Levin

mm: larger stack guard gap, between vmas

2017-06-28T22:57:15Z

[ Upstream commit 1be7107fbe18eed3e319a6c3e83c78254b693acb ] Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

MIPS: mm: Fix definition of R6 cache instruction

2016-08-20T03:08:34Z

[ Upstream commit 4f53989b0652ffe2605221c81ca8ffcfc90aed2a ] Commit a168b8f1cde6 ("MIPS: mm: Add MIPS R6 instruction encodings") added an incorrect definition of the redefined MIPSr6 cache instruction. Executing any kernel code including this instuction results in a reserved instruction exception and kernel panic. Fix the instruction definition. Fixes: a168b8f1cde6588ff7a67699fa11e01bc77a5ddd Signed-off-by: Matt Redfearn Cc: # 4.x- Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/13663/ Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

MIPS: Sync icache & dcache in set_pte_at

2016-06-06T23:12:19Z

[ Upstream commit 37d22a0d798b5c938b277d32cfd86dc231381342 ] It's possible for pages to become visible prior to update_mmu_cache running if a thread within the same address space preempts the current thread or runs simultaneously on another CPU. That is, the following scenario is possible: CPU0 CPU1 write to page flush_dcache_page flush_icache_page set_pte_at map page update_mmu_cache If CPU1 maps the page in between CPU0's set_pte_at, which marks it valid & visible, and update_mmu_cache where the dcache flush occurs then CPU1s icache will fill from stale data (unless it fills from the dcache, in which case all is good, but most MIPS CPUs don't have this property). Commit 4d46a67a3eb8 ("MIPS: Fix race condition in lazy cache flushing.") attempted to fix that by performing the dcache flush in flush_icache_page such that it occurs before the set_pte_at call makes the page visible. However it has the problem that not all code that writes to pages exposed to userland call flush_icache_page. There are many callers of set_pte_at under mm/ and only 2 of them do call flush_icache_page. Thus the race window between a page becoming visible & being coherent between the icache & dcache remains open in some cases. To illustrate some of the cases, a WARN was added to __update_cache with this patch applied that triggered in cases where a page about to be flushed from the dcache was not the last page provided to flush_icache_page. That is, backtraces were obtained for cases in which the race window is left open without this patch. The 2 standout examples follow. When forking a process: [ 15.271842] [<80417630>] __update_cache+0xcc/0x188 [ 15.277274] [<80530394>] copy_page_range+0x56c/0x6ac [ 15.282861] [<8042936c>] copy_process.part.54+0xd40/0x17ac [ 15.289028] [<80429f80>] do_fork+0xe4/0x420 [ 15.293747] [<80413808>] handle_sys+0x128/0x14c When exec'ing an ELF binary: [ 14.445964] [<80417630>] __update_cache+0xcc/0x188 [ 14.451369] [<80538d88>] move_page_tables+0x414/0x498 [ 14.457075] [<8055d848>] setup_arg_pages+0x220/0x318 [ 14.462685] [<805b0f38>] load_elf_binary+0x530/0x12a0 [ 14.468374] [<8055ec3c>] search_binary_handler+0xbc/0x214 [ 14.474444] [<8055f6c0>] do_execveat_common+0x43c/0x67c [ 14.480324] [<8055f938>] do_execve+0x38/0x44 [ 14.485137] [<80413808>] handle_sys+0x128/0x14c These code paths write into a page, call flush_dcache_page then call set_pte_at without flush_icache_page inbetween. The end result is that the icache can become corrupted & userland processes may execute unexpected or invalid code, typically resulting in a reserved instruction exception, a trap or a segfault. Fix this race condition fully by performing any cache maintenance required to keep the icache & dcache in sync in set_pte_at, before the page is made valid. This has the added bonus of ensuring the cache maintenance always happens in one location, rather than being duplicated in flush_icache_page & update_mmu_cache. It also matches the way other architectures solve the same problem (see arm, ia64 & powerpc). Signed-off-by: Paul Burton Reported-by: Ionela Voinescu Cc: Lars Persson Fixes: 4d46a67a3eb8 ("MIPS: Fix race condition in lazy cache flushing.") Cc: Steven J. Hill Cc: David Daney Cc: Huacai Chen Cc: Aneesh Kumar K.V Cc: Andrew Morton Cc: Jerome Marchand Cc: Kirill A. Shutemov Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: stable # v4.1+ Patchwork: https://patchwork.linux-mips.org/patch/12722/ Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

MIPS: Handle highmem pages in __update_cache

2016-06-06T23:12:19Z

[ Upstream commit f4281bba818105c7c91799abe40bc05c0dbdaa25 ] The following patch will expose __update_cache to highmem pages. Handle them by mapping them in for the duration of the cache maintenance, just like in __flush_dcache_page. The code for that isn't shared because we need the page address in __update_cache so sharing became messy. Given that the entirity is an extra 5 lines, just duplicate it. Signed-off-by: Paul Burton Cc: Lars Persson Cc: Andrew Morton Cc: Jerome Marchand Cc: Kirill A. Shutemov Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: stable # v4.1+ Patchwork: https://patchwork.linux-mips.org/patch/12721/ Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

MIPS: Flush highmem pages in __flush_dcache_page

2016-06-06T23:12:19Z

[ Upstream commit 234859e49a15323cf1b2331bdde7f658c4cb45fb ] When flush_dcache_page is called on an executable page, that page is about to be provided to userland & we can presume that the icache contains no valid entries for its address range. However if the icache does not fill from the dcache then we cannot presume that the pages content has been written back as far as the memories that the dcache will fill from (ie. L2 or further out). This was being done for lowmem pages, but not for highmem which can lead to icache corruption. Fix this by mapping highmem pages & flushing their content from the dcache in __flush_dcache_page before providing the page to userland, just as is done for lowmem pages. Signed-off-by: Paul Burton Cc: Lars Persson Cc: Andrew Morton Cc: Kirill A. Shutemov Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/12720/ Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

MIPS: Fix some missing CONFIG_CPU_MIPSR6 #ifdefs

2016-02-15T20:45:26Z

[ Upstream commit 4f33f6c522948fffc345261896042b58dea23754 ] Commit be0c37c985eddc4 (MIPS: Rearrange PTE bits into fixed positions.) defines fixed PTE bits for MIPS R2. Then, commit d7b631419b3d230a4d383 (MIPS: pgtable-bits: Fix XPA damage to R6 definitions.) adds the MIPS R6 definitions in the same way as MIPS R2. But some R6 #ifdefs in the later commit are missing, so in this patch I fix that. Signed-off-by: Huacai Chen Cc: Aurelien Jarno Cc: Steven J. Hill Cc: Fuxin Zhang Cc: Zhangjin Wu Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/12164/ Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

MIPS: dma-default: Fix 32-bit fall back to GFP_DMA

2015-10-22T21:43:23Z

commit 53960059d56ecef67d4ddd546731623641a3d2d1 upstream. If there is a DMA zone (usually 24bit = 16MB I believe), but no DMA32 zone, as is the case for some 32-bit kernels, then massage_gfp_flags() will cause DMA memory allocated for devices with a 32..63-bit coherent_dma_mask to fall back to using __GFP_DMA, even though there may only be 32-bits of physical address available anyway. Correct that case to compare against a mask the size of phys_addr_t instead of always using a 64-bit mask. Signed-off-by: James Hogan Fixes: a2e715a86c6d ("MIPS: DMA: Fix computation of DMA flags from device's coherent_dma_mask.") Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9610/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman