Pull arm64 fixes from Will Deacon: "It's all straightforward apart from the changes to mmap()/mremap() in relation to their handling of address arguments from userspace with non-zero tag bits in the upper byte. The change to brk() is necessary to fix a nasty user-visible regression in malloc(), but we tightened up mmap() and mremap() at the same time because they also allow the user to create virtual aliases by accident. It's much less likely than brk() to matter in practice, but enforcing the principle of "don't permit the creation of mappings using tagged addresses" leads to a straightforward ABI without having to worry about the "but what if a crazy program did foo?" aspect of things. Summary: - Fix regression in malloc() caused by ignored address tags in brk() - Add missing brackets around argument to untagged_addr() macro - Fix clang build when using binutils assembler - Fix silly typo in virtual memory map documentation" * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() docs: arm64: fix trivial spelling enought to enough in memory.rst arm64: memory: Add missing brackets to untagged_addr() macro arm64: lse: Fix LSE atomics with LLVM
Unified · Split
| @@ -129,7 +129,7 @@ this logic. · 128 unmodified lines | |||
| 129 | 129 | ||
| 130 | As a single binary will need to support both 48-bit and 52-bit VA | 130 | As a single binary will need to support both 48-bit and 52-bit VA |
| 131 | spaces, the VMEMMAP must be sized large enough for 52-bit VAs and | 131 | spaces, the VMEMMAP must be sized large enough for 52-bit VAs and |
| 132 | also must be sized large enought to accommodate a fixed PAGE_OFFSET. | 132 | also must be sized large enough to accommodate a fixed PAGE_OFFSET. |
| 133 | 133 | ||
| 134 | Most code in the kernel should not need to consider the VA_BITS, for | 134 | Most code in the kernel should not need to consider the VA_BITS, for |
| 135 | code that does need to know the VA size the variables are | 135 | code that does need to know the VA size the variables are |
| @@ -44,8 +44,15 @@ The AArch64 Tagged Address ABI has two stages of relaxation depending · 43 unmodified lines | |||
| 44 | how the user addresses are used by the kernel: | 44 | how the user addresses are used by the kernel: |
| 45 | 45 | ||
| 46 | 1. User addresses not accessed by the kernel but used for address space | 46 | 1. User addresses not accessed by the kernel but used for address space |
| 47 | management (e.g. ``mmap()``, ``mprotect()``, ``madvise()``). The use | 47 | management (e.g. ``mprotect()``, ``madvise()``). The use of valid |
| 48 | of valid tagged pointers in this context is always allowed. | 48 | tagged pointers in this context is allowed with the exception of |
| 49 | ``brk()``, ``mmap()`` and the ``new_address`` argument to | ||
| 50 | ``mremap()`` as these have the potential to alias with existing | ||
| 51 | user addresses. | ||
| 52 | |||
| 53 | NOTE: This behaviour changed in v5.6 and so some earlier kernels may | ||
| 54 | incorrectly accept valid tagged pointers for the ``brk()``, | ||
| 55 | ``mmap()`` and ``mremap()`` system calls. | ||
| 49 | 56 | ||
| 50 | 2. User addresses accessed by the kernel (e.g. ``write()``). This ABI | 57 | 2. User addresses accessed by the kernel (e.g. ``write()``). This ABI |
| 51 | relaxation is disabled by default and the application thread needs to | 58 | relaxation is disabled by default and the application thread needs to |
| @@ -6,7 +6,7 @@ · 5 unmodified lines | |||
| 6 | 6 | ||
| 7 | #ifdef CONFIG_ARM64_LSE_ATOMICS | 7 | #ifdef CONFIG_ARM64_LSE_ATOMICS |
| 8 | 8 | ||
| 9 | #define __LSE_PREAMBLE ".arch armv8-a+lse\n" | 9 | #define __LSE_PREAMBLE ".arch_extension lse\n" |
| 10 | 10 | ||
| 11 | #include <linux/compiler_types.h> | 11 | #include <linux/compiler_types.h> |
| 12 | #include <linux/export.h> | 12 | #include <linux/export.h> |
| @@ -213,7 +213,7 @@ static inline unsigned long kaslr_offset(void) · 212 unmodified lines | |||
| 213 | ((__force __typeof__(addr))sign_extend64((__force u64)(addr), 55)) | 213 | ((__force __typeof__(addr))sign_extend64((__force u64)(addr), 55)) |
| 214 | 214 | ||
| 215 | #define untagged_addr(addr) ({ \ | 215 | #define untagged_addr(addr) ({ \ |
| 216 | u64 __addr = (__force u64)addr; \ | 216 | u64 __addr = (__force u64)(addr); \ |
| 217 | __addr &= __untagged_addr(__addr); \ | 217 | __addr &= __untagged_addr(__addr); \ |
| 218 | (__force __typeof__(addr))__addr; \ | 218 | (__force __typeof__(addr))__addr; \ |
| 219 | }) | 219 | }) |
| @@ -195,8 +195,6 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) · 194 unmodified lines | |||
| 195 | bool downgraded = false; | 195 | bool downgraded = false; |
| 196 | LIST_HEAD(uf); | 196 | LIST_HEAD(uf); |
| 197 | 197 | ||
| 198 | brk = untagged_addr(brk); | ||
| 199 | |||
| 200 | if (down_write_killable(&mm->mmap_sem)) | 198 | if (down_write_killable(&mm->mmap_sem)) |
| 201 | return -EINTR; | 199 | return -EINTR; |
| 202 | 200 | ||
| @@ -1557,8 +1555,6 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, · 1354 unmodified lines | |||
| 1557 | struct file *file = NULL; | 1555 | struct file *file = NULL; |
| 1558 | unsigned long retval; | 1556 | unsigned long retval; |
| 1559 | 1557 | ||
| 1560 | addr = untagged_addr(addr); | ||
| 1561 | |||
| 1562 | if (!(flags & MAP_ANONYMOUS)) { | 1558 | if (!(flags & MAP_ANONYMOUS)) { |
| 1563 | audit_mmap_fd(fd, flags); | 1559 | audit_mmap_fd(fd, flags); |
| 1564 | file = fget(fd); | 1560 | file = fget(fd); |
| @@ -607,7 +607,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, · 606 unmodified lines | |||
| 607 | LIST_HEAD(uf_unmap); | 607 | LIST_HEAD(uf_unmap); |
| 608 | 608 | ||
| 609 | addr = untagged_addr(addr); | 609 | addr = untagged_addr(addr); |
| 610 | new_addr = untagged_addr(new_addr); | ||
| 611 | 610 | ||
| 612 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) | 611 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) |
| 613 | return ret; | 612 | return ret; |