Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

63f01d85 · Linus Torvalds <[email protected]> · 2020-02-21 16:03:36 -08:00

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

Commit: 63f01d852c75366fb4d15ce217d12c48b69a4bcc
Parents: 28659362 · dcde2373

Merge commit. Changes below are compared with the first parent: 28659362.

Changes

6 files changed · +12 −10

File	Status	Add	Del	Content
Documentation/arm64/memory.rst	modified	+1	−1	View file
Documentation/arm64/tagged-address-abi.rst	modified	+9	−2	View file
arch/arm64/include/asm/lse.h	modified	+1	−1	View file
arch/arm64/include/asm/memory.h	modified	+1	−1	View file
mm/mmap.c	modified	+0	−4	View file
mm/mremap.c	modified	+0	−1	View file

Documentation/arm64/memory.rst

View file

diff --git a/Documentation/arm64/memory.rst b/Documentation/arm64/memory.rst
index 02e0217..cf03b32 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

Documentation/arm64/tagged-address-abi.rst

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diff --git a/Documentation/arm64/tagged-address-abi.rst b/Documentation/arm64/tagged-address-abi.rst
index d4a85d5..4a9d9c7 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

arch/arm64/include/asm/lse.h

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diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h
index d429f77..5d10051 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 <linux/compiler_types.h>
 #include <linux/export.h>

arch/arm64/include/asm/memory.h

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diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index a4f9ca5..4d94676 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;				\
 })

mm/mmap.c

View file

diff --git a/mm/mmap.c b/mm/mmap.c
index 6756b8b..d681a20 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);

mm/mremap.c

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diff --git a/mm/mremap.c b/mm/mremap.c
index 122938d..af36306 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;