From 62a2f00d140b300a2608fe7322f087c4268c45ec Mon Sep 17 00:00:00 2001 From: Kevin Brodsky Date: Tue, 10 May 2016 13:51:54 +0100 Subject: [PATCH] FROMLIST: BACKPORT: [PATCH 3/6] arm64: Refactor vDSO init/setup (cherry pick from url https://patchwork.kernel.org/patch/10060439/) Move the logic for setting up mappings and pages for the vDSO into static functions. This makes the vDSO setup code more consistent with the compat side and will allow to reuse it for the future compat vDSO. Signed-off-by: Kevin Brodsky Signed-off-by: Mark Salyzyn Cc: Catalin Marinas Cc: Will Deacon Cc: Dave Martin Cc: "Eric W. Biederman" Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Bug: 63737556 Bug: 20045882 Change-Id: I13e84479591091669190360f2a7f4d04462e6344 --- arch/arm64/kernel/vdso.c | 110 ++++++++++++++++++++++++--------------- 1 file changed, 67 insertions(+), 43 deletions(-) diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index 13fc2f68d5af..4a75e8cbd3ed 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -39,8 +39,11 @@ #include #include -extern char vdso_start[], vdso_end[]; -static unsigned long vdso_pages __ro_after_init; +struct vdso_mappings { + unsigned long num_code_pages; + struct vm_special_mapping data_mapping; + struct vm_special_mapping code_mapping; +}; /* * The vDSO data page. @@ -150,92 +153,113 @@ out: } #endif /* CONFIG_COMPAT */ -static struct vm_special_mapping vdso_spec[2] __ro_after_init = { - { - .name = "[vvar]", - }, - { - .name = "[vdso]", - }, -}; - -static int __init vdso_init(void) +static int __init vdso_mappings_init(const char *name, + const char *code_start, + const char *code_end, + struct vdso_mappings *mappings) { - int i; + unsigned long i, vdso_pages; struct page **vdso_pagelist; unsigned long pfn; - if (memcmp(vdso_start, "\177ELF", 4)) { - pr_err("vDSO is not a valid ELF object!\n"); + if (memcmp(code_start, "\177ELF", 4)) { + pr_err("%sis not a valid ELF object!\n", name); return -EINVAL; } - vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; + vdso_pages = (code_end - code_start) >> PAGE_SHIFT; /* Allocate the vDSO pagelist, plus a page for the data. */ - vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *), - GFP_KERNEL); + /* + * Allocate space for storing pointers to the vDSO code pages + the + * data page. The pointers must have the same lifetime as the mappings, + * which are static, so there is no need to keep track of the pointer + * array to free it. + */ + vdso_pagelist = kmalloc_array(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_start); + pfn = sym_to_pfn(code_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]; + /* Populate the special mapping structures */ + mappings->data_mapping = (struct vm_special_mapping) { + .name = "[vvar]", + .pages = &vdso_pagelist[0], + }; + + mappings->code_mapping = (struct vm_special_mapping) { + .name = "[vdso]", + .pages = &vdso_pagelist[1], + }; + + mappings->num_code_pages = vdso_pages; return 0; } + +static struct vdso_mappings vdso_mappings __ro_after_init; + +static int __init vdso_init(void) +{ + extern char vdso_start[], vdso_end[]; + + return vdso_mappings_init("vdso", vdso_start, vdso_end, + &vdso_mappings); +} arch_initcall(vdso_init); -int arch_setup_additional_pages(struct linux_binprm *bprm, - int uses_interp) +static int vdso_setup(struct mm_struct *mm, + 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 = vdso_pages << PAGE_SHIFT; + vdso_text_len = mappings->num_code_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; - } + if (IS_ERR_VALUE(vdso_base)) + return PTR_ERR_OR_ZERO(ERR_PTR(vdso_base)); + ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, VM_READ|VM_MAYREAD, - &vdso_spec[0]); + &mappings->data_mapping); if (IS_ERR(ret)) - goto up_fail; + return PTR_ERR_OR_ZERO(ret); 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; + &mappings->code_mapping); + if (!IS_ERR(ret)) + mm->context.vdso = (void *)vdso_base; + + return PTR_ERR_OR_ZERO(ret); +} +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +{ + struct mm_struct *mm = current->mm; + int ret; - up_write(&mm->mmap_sem); - return 0; + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + + ret = vdso_setup(mm, &vdso_mappings); -up_fail: - mm->context.vdso = NULL; up_write(&mm->mmap_sem); - return PTR_ERR(ret); + return ret; } /* -- 2.20.1