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Message-ID: <fb0aeea7eb024efb92c512a873f40aa6ab27898a.1731946386.git.lorenzo.stoakes@oracle.com>
Date: Mon, 18 Nov 2024 16:17:27 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: stable@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Xu <peterx@...hat.com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Mark Brown <broonie@...nel.org>,
"David S . Miller" <davem@...emloft.net>,
Andreas Larsson <andreas@...sler.com>,
"James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>
Subject: [PATCH 6.1.y v2 3/4] mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling
[ Upstream commit 5baf8b037debf4ec60108ccfeccb8636d1dbad81 ]
Currently MTE is permitted in two circumstances (desiring to use MTE
having been specified by the VM_MTE flag) - where MAP_ANONYMOUS is
specified, as checked by arch_calc_vm_flag_bits() and actualised by
setting the VM_MTE_ALLOWED flag, or if the file backing the mapping is
shmem, in which case we set VM_MTE_ALLOWED in shmem_mmap() when the mmap
hook is activated in mmap_region().
The function that checks that, if VM_MTE is set, VM_MTE_ALLOWED is also
set is the arm64 implementation of arch_validate_flags().
Unfortunately, we intend to refactor mmap_region() to perform this check
earlier, meaning that in the case of a shmem backing we will not have
invoked shmem_mmap() yet, causing the mapping to fail spuriously.
It is inappropriate to set this architecture-specific flag in general mm
code anyway, so a sensible resolution of this issue is to instead move the
check somewhere else.
We resolve this by setting VM_MTE_ALLOWED much earlier in do_mmap(), via
the arch_calc_vm_flag_bits() call.
This is an appropriate place to do this as we already check for the
MAP_ANONYMOUS case here, and the shmem file case is simply a variant of
the same idea - we permit RAM-backed memory.
This requires a modification to the arch_calc_vm_flag_bits() signature to
pass in a pointer to the struct file associated with the mapping, however
this is not too egregious as this is only used by two architectures anyway
- arm64 and parisc.
So this patch performs this adjustment and removes the unnecessary
assignment of VM_MTE_ALLOWED in shmem_mmap().
[akpm@...ux-foundation.org: fix whitespace, per Catalin]
Link: https://lkml.kernel.org/r/ec251b20ba1964fb64cf1607d2ad80c47f3873df.1730224667.git.lorenzo.stoakes@oracle.com
Fixes: deb0f6562884 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Suggested-by: Catalin Marinas <catalin.marinas@....com>
Reported-by: Jann Horn <jannh@...gle.com>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
Cc: Andreas Larsson <andreas@...sler.com>
Cc: David S. Miller <davem@...emloft.net>
Cc: Helge Deller <deller@....de>
Cc: James E.J. Bottomley <James.Bottomley@...senPartnership.com>
Cc: Liam R. Howlett <Liam.Howlett@...cle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mark Brown <broonie@...nel.org>
Cc: Peter Xu <peterx@...hat.com>
Cc: Will Deacon <will@...nel.org>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
arch/arm64/include/asm/mman.h | 10 +++++++---
include/linux/mman.h | 7 ++++---
mm/mmap.c | 2 +-
mm/nommu.c | 2 +-
mm/shmem.c | 3 ---
5 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h
index 5966ee4a6154..ef35c52aabd6 100644
--- a/arch/arm64/include/asm/mman.h
+++ b/arch/arm64/include/asm/mman.h
@@ -3,6 +3,8 @@
#define __ASM_MMAN_H__
#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/shmem_fs.h>
#include <linux/types.h>
#include <uapi/asm/mman.h>
@@ -21,19 +23,21 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
}
#define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
-static inline unsigned long arch_calc_vm_flag_bits(unsigned long flags)
+static inline unsigned long arch_calc_vm_flag_bits(struct file *file,
+ unsigned long flags)
{
/*
* Only allow MTE on anonymous mappings as these are guaranteed to be
* backed by tags-capable memory. The vm_flags may be overridden by a
* filesystem supporting MTE (RAM-based).
*/
- if (system_supports_mte() && (flags & MAP_ANONYMOUS))
+ if (system_supports_mte() &&
+ ((flags & MAP_ANONYMOUS) || shmem_file(file)))
return VM_MTE_ALLOWED;
return 0;
}
-#define arch_calc_vm_flag_bits(flags) arch_calc_vm_flag_bits(flags)
+#define arch_calc_vm_flag_bits(file, flags) arch_calc_vm_flag_bits(file, flags)
static inline bool arch_validate_prot(unsigned long prot,
unsigned long addr __always_unused)
diff --git a/include/linux/mman.h b/include/linux/mman.h
index 58b3abd457a3..21ea08b919d9 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -2,6 +2,7 @@
#ifndef _LINUX_MMAN_H
#define _LINUX_MMAN_H
+#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/percpu_counter.h>
@@ -90,7 +91,7 @@ static inline void vm_unacct_memory(long pages)
#endif
#ifndef arch_calc_vm_flag_bits
-#define arch_calc_vm_flag_bits(flags) 0
+#define arch_calc_vm_flag_bits(file, flags) 0
#endif
#ifndef arch_validate_prot
@@ -147,12 +148,12 @@ calc_vm_prot_bits(unsigned long prot, unsigned long pkey)
* Combine the mmap "flags" argument into "vm_flags" used internally.
*/
static inline unsigned long
-calc_vm_flag_bits(unsigned long flags)
+calc_vm_flag_bits(struct file *file, unsigned long flags)
{
return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) |
_calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) |
_calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) |
- arch_calc_vm_flag_bits(flags);
+ arch_calc_vm_flag_bits(file, flags);
}
unsigned long vm_commit_limit(void);
diff --git a/mm/mmap.c b/mm/mmap.c
index 4bfec4df51c2..322677f61d30 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1316,7 +1316,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
* to. we assume access permissions have been handled by the open
* of the memory object, so we don't do any here.
*/
- vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
+ vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(file, flags) |
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
if (flags & MAP_LOCKED)
diff --git a/mm/nommu.c b/mm/nommu.c
index e0428fa57526..859ba6bdeb9c 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -903,7 +903,7 @@ static unsigned long determine_vm_flags(struct file *file,
{
unsigned long vm_flags;
- vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
+ vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(file, flags);
/* vm_flags |= mm->def_flags; */
if (!(capabilities & NOMMU_MAP_DIRECT)) {
diff --git a/mm/shmem.c b/mm/shmem.c
index 0e1fbc53717d..d1a33f66cc7f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2308,9 +2308,6 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
if (ret)
return ret;
- /* arm64 - allow memory tagging on RAM-based files */
- vma->vm_flags |= VM_MTE_ALLOWED;
-
file_accessed(file);
vma->vm_ops = &shmem_vm_ops;
return 0;
--
2.47.0
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