Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping

From: Linus Torvalds
Date: Mon Aug 19 2024 - 16:17:05 EST

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In reply to: Linus Torvalds: "Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping"
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On Mon, 19 Aug 2024 at 13:15, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Ok, I did a quick hack-job to remove that disgusting
> install_special_mapping() legacy case.
>
> With this [..]

I forgot to actually attach that "this". Here it is. For real, this time.

Linus
arch/csky/kernel/vdso.c | 28 +++++++++++++++++++++-------
arch/hexagon/kernel/vdso.c | 14 ++++++++++----
arch/nios2/mm/init.c | 12 ++++++++----
arch/sh/kernel/vsyscall/vsyscall.c | 14 +++++++++++---
arch/x86/um/vdso/vma.c | 12 ++++++++----
include/linux/mm.h | 4 ----
mm/mmap.c | 32 +++++---------------------------
7 files changed, 63 insertions(+), 53 deletions(-)

diff --git a/arch/csky/kernel/vdso.c b/arch/csky/kernel/vdso.c
index 2ca886e4a458..1cd13a2b34eb 100644
--- a/arch/csky/kernel/vdso.c
+++ b/arch/csky/kernel/vdso.c
@@ -45,9 +45,16 @@ arch_initcall(vdso_init);
int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long vdso_base, vdso_len;
int ret;
+ static struct vm_special_mapping vdso_mapping = {
+ .name = "[vdso]",
+ };
+ static struct vm_special_mapping vvar_mapping = {
+ .name = "[vvar]",
+ };

vdso_len = (vdso_pages + 1) << PAGE_SHIFT;

@@ -65,22 +72,29 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
*/
mm->context.vdso = (void *)vdso_base;

- ret =
- install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
+ vdso_mapping.pages = vdso_pagelist;
+ vma =
+ _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
- vdso_pagelist);
+ &vdso_mapping);

- if (unlikely(ret)) {
+ if (unlikely(IS_ERR(vma))) {
+ ret = PTR_ERR(vma);
mm->context.vdso = NULL;
goto end;
}

vdso_base += (vdso_pages << PAGE_SHIFT);
- ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
- (VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
+ vvar_mapping.pages = &vdso_pagelist[vdso_pages];
+ vma = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
+ (VM_READ | VM_MAYREAD), &vvar_mapping);

- if (unlikely(ret))
+ if (unlikely(IS_ERR(vma))) {
+ ret = PTR_ERR(vma);
mm->context.vdso = NULL;
+ goto end;
+ }
+ ret = 0;
end:
mmap_write_unlock(mm);
return ret;
diff --git a/arch/hexagon/kernel/vdso.c b/arch/hexagon/kernel/vdso.c
index 2e4872d62124..f1eb2cd2fd29 100644
--- a/arch/hexagon/kernel/vdso.c
+++ b/arch/hexagon/kernel/vdso.c
@@ -51,7 +51,11 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
int ret;
unsigned long vdso_base;
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
+ static struct vm_special_mapping vdso_mapping = {
+ name = "[vdso]",
+ };

if (mmap_write_lock_killable(mm))
return -EINTR;
@@ -66,16 +70,18 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
}

/* MAYWRITE to allow gdb to COW and set breakpoints. */
- ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
+ vdso_mapping.pages = &&vdso_page;
+ vma = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- &vdso_page);
+ &vdso_mapping);

- if (ret)
+ ret = PTR_ERR(vma);
+ if (IS_ERR(vma))
goto up_fail;

mm->context.vdso = (void *)vdso_base;
-
+ ret = 0;
up_fail:
mmap_write_unlock(mm);
return ret;
diff --git a/arch/nios2/mm/init.c b/arch/nios2/mm/init.c
index 3459df28afee..a2278485de19 100644
--- a/arch/nios2/mm/init.c
+++ b/arch/nios2/mm/init.c
@@ -82,6 +82,10 @@ void __init mmu_init(void)
pgd_t swapper_pg_dir[PTRS_PER_PGD] __aligned(PAGE_SIZE);
pte_t invalid_pte_table[PTRS_PER_PTE] __aligned(PAGE_SIZE);
static struct page *kuser_page[1];
+static struct vm_special_mapping vdso_mapping = {
+ .name = "[vdso]",
+ .pages = kuser_page,
+};

static int alloc_kuser_page(void)
{
@@ -106,18 +110,18 @@ arch_initcall(alloc_kuser_page);
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
- int ret;
+ struct vm_area_struct *vma;

mmap_write_lock(mm);

/* Map kuser helpers to user space address */
- ret = install_special_mapping(mm, KUSER_BASE, KUSER_SIZE,
+ vma = _install_special_mapping(mm, KUSER_BASE, KUSER_SIZE,
VM_READ | VM_EXEC | VM_MAYREAD |
- VM_MAYEXEC, kuser_page);
+ VM_MAYEXEC, &vdso_mapping);

mmap_write_unlock(mm);

- return ret;
+ return IS_ERR(vma) ? PTR_ERR(vma) : 0;
}

const char *arch_vma_name(struct vm_area_struct *vma)
diff --git a/arch/sh/kernel/vsyscall/vsyscall.c b/arch/sh/kernel/vsyscall/vsyscall.c
index 1bd85a6949c4..5e68ab7a8898 100644
--- a/arch/sh/kernel/vsyscall/vsyscall.c
+++ b/arch/sh/kernel/vsyscall/vsyscall.c
@@ -36,6 +36,10 @@ __setup("vdso=", vdso_setup);
*/
extern const char vsyscall_trapa_start, vsyscall_trapa_end;
static struct page *syscall_pages[1];
+static struct vm_special_mapping vdso_mapping = {
+ .name = "[vdso]",
+ .pages = syscall_pages;
+};

int __init vsyscall_init(void)
{
@@ -58,6 +62,7 @@ int __init vsyscall_init(void)
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
unsigned long addr;
int ret;

@@ -70,14 +75,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
goto up_fail;
}

- ret = install_special_mapping(mm, addr, PAGE_SIZE,
+ vdso_mapping.pages = syscall_pages;
+ vma = _install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_EXEC |
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
- syscall_pages);
- if (unlikely(ret))
+ &vdso_mapping);
+ ret = PTR_ERR(vma);
+ if (unlikely(IS_ERR(vma)))
goto up_fail;

current->mm->context.vdso = (void *)addr;
+ ret = 0;

up_fail:
mmap_write_unlock(mm);
diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c
index 76d9f6ce7a3d..f238f7b33cdd 100644
--- a/arch/x86/um/vdso/vma.c
+++ b/arch/x86/um/vdso/vma.c
@@ -52,8 +52,11 @@ subsys_initcall(init_vdso);

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
- int err;
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
+ static struct vm_special_mapping vdso_mapping = {
+ .name = "[vdso]",
+ };

if (!vdso_enabled)
return 0;
@@ -61,12 +64,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (mmap_write_lock_killable(mm))
return -EINTR;

- err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
+ vdso_mapping.pages = vdsop;
+ vma = _install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- vdsop);
+ &vdso_mapping);

mmap_write_unlock(mm);

- return err;
+ return IS_ERR(vma) ? PTR_ERR(vma) : 0;
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6549d0979b28..7b7e4797c0fd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3381,10 +3381,6 @@ extern struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
unsigned long flags,
const struct vm_special_mapping *spec);
-/* This is an obsolete alternative to _install_special_mapping. */
-extern int install_special_mapping(struct mm_struct *mm,
- unsigned long addr, unsigned long len,
- unsigned long flags, struct page **pages);

unsigned long randomize_stack_top(unsigned long stack_top);
unsigned long randomize_page(unsigned long start, unsigned long range);
diff --git a/mm/mmap.c b/mm/mmap.c
index d0dfc85b209b..ece92e6c3ead 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3665,27 +3665,17 @@ static const struct vm_operations_struct special_mapping_vmops = {
.may_split = special_mapping_split,
};

-static const struct vm_operations_struct legacy_special_mapping_vmops = {
- .close = special_mapping_close,
- .fault = special_mapping_fault,
-};
-
static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
pgoff_t pgoff;
struct page **pages;
+ struct vm_special_mapping *sm = vma->vm_private_data;

- if (vma->vm_ops == &legacy_special_mapping_vmops) {
- pages = vma->vm_private_data;
- } else {
- struct vm_special_mapping *sm = vma->vm_private_data;
+ if (sm->fault)
+ return sm->fault(sm, vmf->vma, vmf);

- if (sm->fault)
- return sm->fault(sm, vmf->vma, vmf);
-
- pages = sm->pages;
- }
+ pages = sm->pages;

for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
pgoff--;
@@ -3740,8 +3730,7 @@ bool vma_is_special_mapping(const struct vm_area_struct *vma,
const struct vm_special_mapping *sm)
{
return vma->vm_private_data == sm &&
- (vma->vm_ops == &special_mapping_vmops ||
- vma->vm_ops == &legacy_special_mapping_vmops);
+ vma->vm_ops == &special_mapping_vmops;
}

/*
@@ -3762,17 +3751,6 @@ struct vm_area_struct *_install_special_mapping(
&special_mapping_vmops);
}

-int install_special_mapping(struct mm_struct *mm,
- unsigned long addr, unsigned long len,
- unsigned long vm_flags, struct page **pages)
-{
- struct vm_area_struct *vma = __install_special_mapping(
- mm, addr, len, vm_flags, (void *)pages,
- &legacy_special_mapping_vmops);
-
- return PTR_ERR_OR_ZERO(vma);
-}
-
static DEFINE_MUTEX(mm_all_locks_mutex);

static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)

Next message: Moger, Babu: "Re: [PATCH 1/7] x86/cpufeatures: Add support for L3 Smart Data Cache Injection Allocation Enforcement"
Previous message: Usama Arif: "Re: [PATCH v4 4/6] mm: Introduce a pageflag for partially mapped folios"
In reply to: Linus Torvalds: "Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping"
Next in thread: Andrew Morton: "Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping"
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