[PATCH v7 11/25] arm64: Refactor vDSO code

Vincenzo Frascino
2019-06-21T09:54:58Z

Most of the code for initializing the vDSOs in arm64 and compat will
be in common, hence a refactor of the current code is required to avoid
duplication and simplify maintainability.

Refactor vdso.c to simplify the implementation of arm64 vDSO compat
(which will be pushed with a future patch).

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
---
arch/arm64/kernel/vdso.c | 215 ++++++++++++++++++++++++++-------------
1 file changed, 144 insertions(+), 71 deletions(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 23c38303a52a..aa1fb25a9fe4 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -40,7 +40,31 @@
#include <asm/vdso.h>

extern char vdso_start[], vdso_end[];
-static unsigned long vdso_pages __ro_after_init;
+
+/* vdso_lookup arch_index */
+enum arch_vdso_type {
+ ARM64_VDSO = 0,
+};
+#define VDSO_TYPES (ARM64_VDSO + 1)
+
+struct __vdso_abi {
+ const char *name;
+ const char *vdso_code_start;
+ const char *vdso_code_end;
+ unsigned long vdso_pages;
+ /* Data Mapping */
+ struct vm_special_mapping *dm;
+ /* Code Mapping */
+ struct vm_special_mapping *cm;
+};
+
+static struct __vdso_abi vdso_lookup[VDSO_TYPES] __ro_after_init = {
+ {
+ .name = "vdso",
+ .vdso_code_start = vdso_start,
+ .vdso_code_end = vdso_end,
+ },
+};

/*
* The vDSO data page.
@@ -51,10 +75,110 @@ static union {
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = vdso_data_store.data;

+static int __vdso_remap(enum arch_vdso_type arch_index,
+ const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+ unsigned long vdso_size = vdso_lookup[arch_index].vdso_code_end -
+ vdso_lookup[arch_index].vdso_code_start;
+
+ if (vdso_size != new_size)
+ return -EINVAL;
+
+ current->mm->context.vdso = (void *)new_vma->vm_start;
+
+ return 0;
+}
+
+static int __vdso_init(enum arch_vdso_type arch_index)
+{
+ int i;
+ struct page **vdso_pagelist;
+ unsigned long pfn;
+
+ if (memcmp(vdso_lookup[arch_index].vdso_code_start, "\177ELF", 4)) {
+ pr_err("vDSO is not a valid ELF object!\n");
+ return -EINVAL;
+ }
+
+ vdso_lookup[arch_index].vdso_pages = (
+ vdso_lookup[arch_index].vdso_code_end -
+ vdso_lookup[arch_index].vdso_code_start) >>
+ PAGE_SHIFT;
+
+ /* Allocate the vDSO pagelist, plus a page for the data. */
+ vdso_pagelist = kcalloc(vdso_lookup[arch_index].vdso_pages + 1,
+ sizeof(struct page *),
+ GFP_KERNEL);
+ if (vdso_pagelist == NULL)
+ return -ENOMEM;
+
+ /* Grab the vDSO data page. */
+ vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
+
+
+ /* Grab the vDSO code pages. */
+ pfn = sym_to_pfn(vdso_lookup[arch_index].vdso_code_start);
+
+ for (i = 0; i < vdso_lookup[arch_index].vdso_pages; i++)
+ vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
+
+ vdso_lookup[arch_index].dm->pages = &vdso_pagelist[0];
+ vdso_lookup[arch_index].cm->pages = &vdso_pagelist[1];
+
+ return 0;
+}
+
+static int __setup_additional_pages(enum arch_vdso_type arch_index,
+ struct mm_struct *mm,
+ struct linux_binprm *bprm,
+ int uses_interp)
+{
+ unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
+ void *ret;
+
+ vdso_text_len = vdso_lookup[arch_index].vdso_pages << PAGE_SHIFT;
+ /* Be sure to map the data page */
+ vdso_mapping_len = vdso_text_len + PAGE_SIZE;
+
+ vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
+ if (IS_ERR_VALUE(vdso_base)) {
+ ret = ERR_PTR(vdso_base);
+ goto up_fail;
+ }
+
+ ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
+ VM_READ|VM_MAYREAD,
+ vdso_lookup[arch_index].dm);
+ if (IS_ERR(ret))
+ goto up_fail;
+
+ vdso_base += PAGE_SIZE;
+ mm->context.vdso = (void *)vdso_base;
+ ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+ vdso_lookup[arch_index].cm);
+ if (IS_ERR(ret))
+ goto up_fail;
+
+ return 0;
+
+up_fail:
+ mm->context.vdso = NULL;
+ return PTR_ERR(ret);
+}
+
#ifdef CONFIG_COMPAT
/*
* Create and map the vectors page for AArch32 tasks.
*/
+/*
+ * aarch32_vdso_pages:
+ * 0 - kuser helpers
+ * 1 - sigreturn code
+ */
#define C_VECTORS 0
#define C_SIGPAGE 1
#define C_PAGES (C_SIGPAGE + 1)
@@ -183,18 +307,18 @@ int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
static int vdso_mremap(const struct vm_special_mapping *sm,
struct vm_area_struct *new_vma)
{
- unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
- unsigned long vdso_size = vdso_end - vdso_start;
-
- if (vdso_size != new_size)
- return -EINVAL;
-
- current->mm->context.vdso = (void *)new_vma->vm_start;
-
- return 0;
+ return __vdso_remap(ARM64_VDSO, sm, new_vma);
}

-static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
+/*
+ * aarch64_vdso_pages:
+ * 0 - vvar
+ * 1 - vdso
+ */
+#define A_VVAR 0
+#define A_VDSO 1
+#define A_PAGES (A_VDSO + 1)
+static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = {
{
.name = "[vvar]",
},
@@ -206,37 +330,10 @@ static struct vm_special_mapping vdso_spec[2] __ro_after_init = {

static int __init vdso_init(void)
{
- int i;
- struct page **vdso_pagelist;
- unsigned long pfn;
-
- if (memcmp(vdso_start, "\177ELF", 4)) {
- pr_err("vDSO is not a valid ELF object!\n");
- return -EINVAL;
- }
-
- vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
-
- /* Allocate the vDSO pagelist, plus a page for the data. */
- vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
- GFP_KERNEL);
- if (vdso_pagelist == NULL)
- return -ENOMEM;
-
- /* Grab the vDSO data page. */
- vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
-
+ vdso_lookup[ARM64_VDSO].dm = &vdso_spec[A_VVAR];
+ vdso_lookup[ARM64_VDSO].cm = &vdso_spec[A_VDSO];

- /* Grab the vDSO code pages. */
- pfn = sym_to_pfn(vdso_start);
-
- for (i = 0; i < vdso_pages; i++)
- vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
-
- vdso_spec[0].pages = &vdso_pagelist[0];
- vdso_spec[1].pages = &vdso_pagelist[1];
-
- return 0;
+ return __vdso_init(ARM64_VDSO);
}
arch_initcall(vdso_init);

@@ -244,41 +341,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
struct mm_struct *mm = current->mm;
- unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
- void *ret;
-
- vdso_text_len = vdso_pages << PAGE_SHIFT;
- /* Be sure to map the data page */
- vdso_mapping_len = vdso_text_len + PAGE_SIZE;
+ int ret;

if (down_write_killable(&mm->mmap_sem))
return -EINTR;
- vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
- if (IS_ERR_VALUE(vdso_base)) {
- ret = ERR_PTR(vdso_base);
- goto up_fail;
- }
- ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
- VM_READ|VM_MAYREAD,
- &vdso_spec[0]);
- if (IS_ERR(ret))
- goto up_fail;
-
- vdso_base += PAGE_SIZE;
- mm->context.vdso = (void *)vdso_base;
- ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- &vdso_spec[1]);
- if (IS_ERR(ret))
- goto up_fail;

+ ret = __setup_additional_pages(ARM64_VDSO,
+ mm,
+ bprm,
+ uses_interp);

up_write(&mm->mmap_sem);
- return 0;

-up_fail:
- mm->context.vdso = NULL;
- up_write(&mm->mmap_sem);
- return PTR_ERR(ret);
+ return ret;
}
--
2.21.0