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Message-Id: <20250624-anon_name_cleanup-v2-2-600075462a11@suse.cz>
Date: Tue, 24 Jun 2025 15:03:46 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Andrew Morton <akpm@...ux-foundation.org>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
David Hildenbrand <david@...hat.com>, Jann Horn <jannh@...gle.com>,
Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>,
Michal Hocko <mhocko@...e.com>, Colin Cross <ccross@...gle.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH v2 2/4] mm, madvise: extract mm code from prctl_set_vma()
to mm/madvise.c
Setting anon_name is done via madvise_set_anon_name() and behaves a lot
of like other madvise operations. However, apparently because madvise()
has lacked the 4th argument and prctl() not, the userspace entry point
has been implemented via prctl(PR_SET_VMA, ...) and handled first by
prctl_set_vma().
Currently prctl_set_vma() lives in kernel/sys.c but setting the
vma->anon_name is mm-specific code so extract it to a new
set_anon_vma_name() function under mm. mm/madvise.c seems to be the most
straightforward place as that's where madvise_set_anon_name() lives.
Stop declaring the latter in mm.h and instead declare
set_anon_vma_name().
Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
include/linux/mm.h | 14 +++++++-------
kernel/sys.c | 50 +-------------------------------------------------
mm/madvise.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 58 insertions(+), 58 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e0549f3d681f6c7a78e8dfa341a810e5a8f96c1..ef40f68c1183d4c95016575a4ee0171e12df9ba4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4059,14 +4059,14 @@ unsigned long wp_shared_mapping_range(struct address_space *mapping,
#endif
#ifdef CONFIG_ANON_VMA_NAME
-int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
- unsigned long len_in,
- struct anon_vma_name *anon_name);
+int set_anon_vma_name(unsigned long addr, unsigned long size,
+ const char __user *uname);
#else
-static inline int
-madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
- unsigned long len_in, struct anon_vma_name *anon_name) {
- return 0;
+static inline
+int set_anon_vma_name(unsigned long addr, unsigned long size,
+ const char __user *uname)
+{
+ return -EINVAL;
}
#endif
diff --git a/kernel/sys.c b/kernel/sys.c
index adc0de0aa364aebb23999f621717a5d32599921c..b153fb345ada28ea1a33386a32bcce9cb1b23475 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2343,54 +2343,14 @@ int __weak arch_lock_shadow_stack_status(struct task_struct *t, unsigned long st
#define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE)
-#ifdef CONFIG_ANON_VMA_NAME
-
-#define ANON_VMA_NAME_MAX_LEN 80
-#define ANON_VMA_NAME_INVALID_CHARS "\\`$[]"
-
-static inline bool is_valid_name_char(char ch)
-{
- /* printable ascii characters, excluding ANON_VMA_NAME_INVALID_CHARS */
- return ch > 0x1f && ch < 0x7f &&
- !strchr(ANON_VMA_NAME_INVALID_CHARS, ch);
-}
-
static int prctl_set_vma(unsigned long opt, unsigned long addr,
unsigned long size, unsigned long arg)
{
- struct mm_struct *mm = current->mm;
- const char __user *uname;
- struct anon_vma_name *anon_name = NULL;
int error;
switch (opt) {
case PR_SET_VMA_ANON_NAME:
- uname = (const char __user *)arg;
- if (uname) {
- char *name, *pch;
-
- name = strndup_user(uname, ANON_VMA_NAME_MAX_LEN);
- if (IS_ERR(name))
- return PTR_ERR(name);
-
- for (pch = name; *pch != '\0'; pch++) {
- if (!is_valid_name_char(*pch)) {
- kfree(name);
- return -EINVAL;
- }
- }
- /* anon_vma has its own copy */
- anon_name = anon_vma_name_alloc(name);
- kfree(name);
- if (!anon_name)
- return -ENOMEM;
-
- }
-
- mmap_write_lock(mm);
- error = madvise_set_anon_name(mm, addr, size, anon_name);
- mmap_write_unlock(mm);
- anon_vma_name_put(anon_name);
+ error = set_anon_vma_name(addr, size, (const char __user *)arg);
break;
default:
error = -EINVAL;
@@ -2399,14 +2359,6 @@ static int prctl_set_vma(unsigned long opt, unsigned long addr,
return error;
}
-#else /* CONFIG_ANON_VMA_NAME */
-static int prctl_set_vma(unsigned long opt, unsigned long start,
- unsigned long size, unsigned long arg)
-{
- return -EINVAL;
-}
-#endif /* CONFIG_ANON_VMA_NAME */
-
static inline unsigned long get_current_mdwe(void)
{
unsigned long ret = 0;
diff --git a/mm/madvise.c b/mm/madvise.c
index fca0e9b3e844ad766e83ac04cc0d7f4099c74005..7e8819b5e9a0f183213ffe19d7e52bd5fda5f49d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -134,8 +134,8 @@ static int replace_anon_vma_name(struct vm_area_struct *vma,
return 0;
}
-int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
- unsigned long len_in, struct anon_vma_name *anon_name)
+static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
+ unsigned long len_in, struct anon_vma_name *anon_name)
{
unsigned long end;
unsigned long len;
@@ -2096,3 +2096,51 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
out:
return ret;
}
+
+#ifdef CONFIG_ANON_VMA_NAME
+
+#define ANON_VMA_NAME_MAX_LEN 80
+#define ANON_VMA_NAME_INVALID_CHARS "\\`$[]"
+
+static inline bool is_valid_name_char(char ch)
+{
+ /* printable ascii characters, excluding ANON_VMA_NAME_INVALID_CHARS */
+ return ch > 0x1f && ch < 0x7f &&
+ !strchr(ANON_VMA_NAME_INVALID_CHARS, ch);
+}
+
+int set_anon_vma_name(unsigned long addr, unsigned long size,
+ const char __user *uname)
+{
+ struct anon_vma_name *anon_name = NULL;
+ struct mm_struct *mm = current->mm;
+ int error;
+
+ if (uname) {
+ char *name, *pch;
+
+ name = strndup_user(uname, ANON_VMA_NAME_MAX_LEN);
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+
+ for (pch = name; *pch != '\0'; pch++) {
+ if (!is_valid_name_char(*pch)) {
+ kfree(name);
+ return -EINVAL;
+ }
+ }
+ /* anon_vma has its own copy */
+ anon_name = anon_vma_name_alloc(name);
+ kfree(name);
+ if (!anon_name)
+ return -ENOMEM;
+ }
+
+ mmap_write_lock(mm);
+ error = madvise_set_anon_name(mm, addr, size, anon_name);
+ mmap_write_unlock(mm);
+ anon_vma_name_put(anon_name);
+
+ return error;
+}
+#endif
--
2.50.0
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