From dd1f6308b28edf0452dd5dc7877992903ec61e69 Mon Sep 17 00:00:00 2001 From: Vincenzo Frascino Date: Tue, 18 Feb 2020 16:49:06 +0000 Subject: arm64: lse: Fix LSE atomics with LLVM Commit e0d5896bd356 ("arm64: lse: fix LSE atomics with LLVM's integrated assembler") broke the build when clang is used in connjunction with the binutils assembler ("-no-integrated-as"). This happens because __LSE_PREAMBLE is defined as ".arch armv8-a+lse", which overrides the version of the CPU architecture passed via the "-march" paramter to gas: $ aarch64-none-linux-gnu-as -EL -I ./arch/arm64/include -I ./arch/arm64/include/generated -I ./include -I ./include -I ./arch/arm64/include/uapi -I ./arch/arm64/include/generated/uapi -I ./include/uapi -I ./include/generated/uapi -I ./init -I ./init -march=armv8.3-a -o init/do_mounts.o /tmp/do_mounts-d7992a.s /tmp/do_mounts-d7992a.s: Assembler messages: /tmp/do_mounts-d7992a.s:1959: Error: selected processor does not support `autiasp' /tmp/do_mounts-d7992a.s:2021: Error: selected processor does not support `paciasp' /tmp/do_mounts-d7992a.s:2157: Error: selected processor does not support `autiasp' /tmp/do_mounts-d7992a.s:2175: Error: selected processor does not support `paciasp' /tmp/do_mounts-d7992a.s:2494: Error: selected processor does not support `autiasp' Fix the issue by replacing ".arch armv8-a+lse" with ".arch_extension lse". Sami confirms that the clang integrated assembler does now support the '.arch_extension' directive, so this change will be fine even for LTO builds in future. Fixes: e0d5896bd356cd ("arm64: lse: fix LSE atomics with LLVM's integrated assembler") Cc: Catalin Marinas Cc: Will Deacon Reported-by: Amit Kachhap Tested-by: Sami Tolvanen Signed-off-by: Vincenzo Frascino Signed-off-by: Will Deacon --- arch/arm64/include/asm/lse.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h index d429f7701c36..5d10051c3e62 100644 --- a/arch/arm64/include/asm/lse.h +++ b/arch/arm64/include/asm/lse.h @@ -6,7 +6,7 @@ #ifdef CONFIG_ARM64_LSE_ATOMICS -#define __LSE_PREAMBLE ".arch armv8-a+lse\n" +#define __LSE_PREAMBLE ".arch_extension lse\n" #include #include -- cgit v1.2.3 From d0022c0ef29b78bcbe8a5c5894bd2307143afce1 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 19 Feb 2020 10:19:13 +0000 Subject: arm64: memory: Add missing brackets to untagged_addr() macro Add brackets around the evaluation of the 'addr' parameter to the untagged_addr() macro so that the cast to 'u64' applies to the result of the expression. Cc: Fixes: 597399d0cb91 ("arm64: tags: Preserve tags for addresses translated via TTBR1") Reported-by: Linus Torvalds Signed-off-by: Will Deacon --- arch/arm64/include/asm/memory.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index a4f9ca5479b0..4d94676e5a8b 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -213,7 +213,7 @@ static inline unsigned long kaslr_offset(void) ((__force __typeof__(addr))sign_extend64((__force u64)(addr), 55)) #define untagged_addr(addr) ({ \ - u64 __addr = (__force u64)addr; \ + u64 __addr = (__force u64)(addr); \ __addr &= __untagged_addr(__addr); \ (__force __typeof__(addr))__addr; \ }) -- cgit v1.2.3 From ce4a64e1f656138e2a1481049ea554720f86b43a Mon Sep 17 00:00:00 2001 From: Scott Branden Date: Wed, 19 Feb 2020 14:14:03 -0800 Subject: docs: arm64: fix trivial spelling enought to enough in memory.rst Fix trivial spelling error enought to enough in memory.rst. Cc: trivial@kernel.org Signed-off-by: Scott Branden Signed-off-by: Will Deacon --- Documentation/arm64/memory.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/arm64/memory.rst b/Documentation/arm64/memory.rst index 02e02175e6f5..cf03b3290800 100644 --- a/Documentation/arm64/memory.rst +++ b/Documentation/arm64/memory.rst @@ -129,7 +129,7 @@ this logic. As a single binary will need to support both 48-bit and 52-bit VA spaces, the VMEMMAP must be sized large enough for 52-bit VAs and -also must be sized large enought to accommodate a fixed PAGE_OFFSET. +also must be sized large enough to accommodate a fixed PAGE_OFFSET. Most code in the kernel should not need to consider the VA_BITS, for code that does need to know the VA size the variables are -- cgit v1.2.3 From dcde237319e626d1ec3c9d8b7613032f0fd4663a Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Wed, 19 Feb 2020 12:31:56 +0000 Subject: mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() Currently the arm64 kernel ignores the top address byte passed to brk(), mmap() and mremap(). When the user is not aware of the 56-bit address limit or relies on the kernel to return an error, untagging such pointers has the potential to create address aliases in user-space. Passing a tagged address to munmap(), madvise() is permitted since the tagged pointer is expected to be inside an existing mapping. The current behaviour breaks the existing glibc malloc() implementation which relies on brk() with an address beyond 56-bit to be rejected by the kernel. Remove untagging in the above functions by partially reverting commit ce18d171cb73 ("mm: untag user pointers in mmap/munmap/mremap/brk"). In addition, update the arm64 tagged-address-abi.rst document accordingly. Link: https://bugzilla.redhat.com/1797052 Fixes: ce18d171cb73 ("mm: untag user pointers in mmap/munmap/mremap/brk") Cc: # 5.4.x- Cc: Florian Weimer Reviewed-by: Andrew Morton Reported-by: Victor Stinner Acked-by: Will Deacon Acked-by: Andrey Konovalov Signed-off-by: Catalin Marinas Signed-off-by: Will Deacon --- Documentation/arm64/tagged-address-abi.rst | 11 +++++++++-- mm/mmap.c | 4 ---- mm/mremap.c | 1 - 3 files changed, 9 insertions(+), 7 deletions(-) diff --git a/Documentation/arm64/tagged-address-abi.rst b/Documentation/arm64/tagged-address-abi.rst index d4a85d535bf9..4a9d9c794ee5 100644 --- a/Documentation/arm64/tagged-address-abi.rst +++ b/Documentation/arm64/tagged-address-abi.rst @@ -44,8 +44,15 @@ The AArch64 Tagged Address ABI has two stages of relaxation depending how the user addresses are used by the kernel: 1. User addresses not accessed by the kernel but used for address space - management (e.g. ``mmap()``, ``mprotect()``, ``madvise()``). The use - of valid tagged pointers in this context is always allowed. + management (e.g. ``mprotect()``, ``madvise()``). The use of valid + tagged pointers in this context is allowed with the exception of + ``brk()``, ``mmap()`` and the ``new_address`` argument to + ``mremap()`` as these have the potential to alias with existing + user addresses. + + NOTE: This behaviour changed in v5.6 and so some earlier kernels may + incorrectly accept valid tagged pointers for the ``brk()``, + ``mmap()`` and ``mremap()`` system calls. 2. User addresses accessed by the kernel (e.g. ``write()``). This ABI relaxation is disabled by default and the application thread needs to diff --git a/mm/mmap.c b/mm/mmap.c index 6756b8bb0033..d681a20eb4ea 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -195,8 +195,6 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) bool downgraded = false; LIST_HEAD(uf); - brk = untagged_addr(brk); - if (down_write_killable(&mm->mmap_sem)) return -EINTR; @@ -1557,8 +1555,6 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, struct file *file = NULL; unsigned long retval; - addr = untagged_addr(addr); - if (!(flags & MAP_ANONYMOUS)) { audit_mmap_fd(fd, flags); file = fget(fd); diff --git a/mm/mremap.c b/mm/mremap.c index 122938dcec15..af363063ea23 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -607,7 +607,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, LIST_HEAD(uf_unmap); addr = untagged_addr(addr); - new_addr = untagged_addr(new_addr); if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) return ret; -- cgit v1.2.3