[RFC PATCH v2 1/8] arm64: Refactor vDSO setup
Kevin Brodsky
kevin.brodsky at arm.com
Thu Oct 27 09:30:51 PDT 2016
Move the logic for setting up mappings and pages for the vDSO into
static functions with a clear interface. This will allow to reuse the
setup code for the future compat vDSO.
Signed-off-by: Kevin Brodsky <kevin.brodsky at arm.com>
---
arch/arm64/kernel/vdso.c | 177 ++++++++++++++++++++++++++---------------------
1 file changed, 98 insertions(+), 79 deletions(-)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index a2c2478e7d78..c239b1c15eb3 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -37,8 +37,10 @@
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>
-extern char vdso_start, vdso_end;
-static unsigned long vdso_pages __ro_after_init;
+struct vdso_mappings {
+ unsigned long num_pages;
+ struct vm_special_mapping data_mapping, code_mapping;
+};
/*
* The vDSO data page.
@@ -49,6 +51,92 @@ static union {
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = &vdso_data_store.data;
+static int __init setup_vdso_mappings(const char *name,
+ const char *code_start,
+ const char *code_end,
+ struct vdso_mappings *mappings)
+{
+ unsigned long i, num_pages;
+ struct page **pages;
+
+ if (memcmp(code_start, "\177ELF", 4)) {
+ pr_err("%s is not a valid ELF object!\n", name);
+ return -EINVAL;
+ }
+
+ num_pages = (code_end - code_start) >> PAGE_SHIFT;
+ pr_info("%s: %ld pages (%ld code @ %p, %ld data @ %p)\n",
+ name, num_pages + 1, num_pages, code_start, 1L, vdso_data);
+
+ /* Allocate the vDSO code pages, plus a page for the data. */
+ pages = kcalloc(num_pages + 1, sizeof(struct page *), GFP_KERNEL);
+ if (pages == NULL)
+ return -ENOMEM;
+
+ /* Grab the vDSO data page. */
+ pages[0] = pfn_to_page(PHYS_PFN(__pa(vdso_data)));
+
+ /* Grab the vDSO code pages. */
+ for (i = 0; i < num_pages; i++)
+ pages[i + 1] = pfn_to_page(PHYS_PFN(__pa(code_start)) + i);
+
+ /* Populate the special mapping structures */
+ mappings->data_mapping = (struct vm_special_mapping) {
+ .name = "[vvar]",
+ .pages = &pages[0],
+ };
+
+ mappings->code_mapping = (struct vm_special_mapping) {
+ .name = "[vdso]",
+ .pages = &pages[1],
+ };
+
+ mappings->num_pages = num_pages;
+ return 0;
+}
+
+static int setup_vdso_pages(const struct vdso_mappings *mappings)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
+ void *ret;
+
+ vdso_text_len = mappings->num_pages << PAGE_SHIFT;
+ /* Be sure to map the data page */
+ vdso_mapping_len = vdso_text_len + PAGE_SIZE;
+
+ 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,
+ &mappings->data_mapping);
+ 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,
+ &mappings->code_mapping);
+ if (IS_ERR(ret))
+ goto up_fail;
+
+
+ up_write(&mm->mmap_sem);
+ return 0;
+
+up_fail:
+ mm->context.vdso = NULL;
+ up_write(&mm->mmap_sem);
+ return PTR_ERR(ret);
+}
+
#ifdef CONFIG_COMPAT
/*
* Create and map the vectors page for AArch32 tasks.
@@ -71,11 +159,11 @@ static int __init alloc_vectors_page(void)
/* kuser helpers */
memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start,
- kuser_sz);
+ kuser_sz);
/* sigreturn code */
memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,
- __aarch32_sigret_code_start, sigret_sz);
+ __aarch32_sigret_code_start, sigret_sz);
flush_icache_range(vpage, vpage + PAGE_SIZE);
vectors_page[0] = virt_to_page(vpage);
@@ -110,90 +198,21 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
}
#endif /* CONFIG_COMPAT */
-static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
- {
- .name = "[vvar]",
- },
- {
- .name = "[vdso]",
- },
-};
+extern char vdso_start, vdso_end;
+
+static struct vdso_mappings vdso_mappings __ro_after_init;
static int __init vdso_init(void)
{
- int i;
- struct page **vdso_pagelist;
-
- 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;
- pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
- vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data);
-
- /* 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] = pfn_to_page(PHYS_PFN(__pa(vdso_data)));
-
- /* Grab the vDSO code pages. */
- for (i = 0; i < vdso_pages; i++)
- vdso_pagelist[i + 1] = pfn_to_page(PHYS_PFN(__pa(&vdso_start)) + i);
-
- vdso_spec[0].pages = &vdso_pagelist[0];
- vdso_spec[1].pages = &vdso_pagelist[1];
-
- return 0;
+ return setup_vdso_mappings("vdso", &vdso_start, &vdso_end,
+ &vdso_mappings);
}
arch_initcall(vdso_init);
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;
-
- 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;
-
-
- up_write(&mm->mmap_sem);
- return 0;
-
-up_fail:
- mm->context.vdso = NULL;
- up_write(&mm->mmap_sem);
- return PTR_ERR(ret);
+ return setup_vdso_pages(&vdso_mappings);
}
/*
--
2.10.0
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