FROMLIST: BACKPORT: [PATCH 5/6] arm64: compat: 32-bit vDSO setup

(cherry pick from url https://patchwork.kernel.org/patch/10060459/)

If the compat vDSO is enabled, install it in compat processes. In this
case, the compat vDSO replaces the sigreturn page (it provides its own
sigreturn trampolines).

Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Bug: 63737556
Bug: 20045882
Change-Id: Ia6acf4c3ffea636bc750ac00853ea762c182e5b5

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 17697320ce29c0d977cf8fa18884963687919871..cac59b9b7d744b915f6112e2392e6b4dfeaad93b 100644 (file)
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -57,6 +57,7 @@ struct vdso_data *vdso_data = &vdso_data_store.data;
 /*
  * Create and map the vectors page for AArch32 tasks.
  */
+#if !defined(CONFIG_VDSO32) || defined(CONFIG_KUSER_HELPERS)
 static struct page *vectors_page[] __ro_after_init;
 static const struct vm_special_mapping compat_vdso_spec[] = {
        {
@@ -72,6 +73,7 @@ static const struct vm_special_mapping compat_vdso_spec[] = {
 #endif
 };
 static struct page *vectors_page[ARRAY_SIZE(compat_vdso_spec)] __ro_after_init;
+#endif
 
 static int __init alloc_vectors_page(void)
 {
@@ -81,6 +83,7 @@ static int __init alloc_vectors_page(void)
        unsigned long kuser_vpage;
 #endif
 
+#ifndef CONFIG_VDSO32
        extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
        size_t sigret_sz =
                __aarch32_sigret_code_end - __aarch32_sigret_code_start;
@@ -89,19 +92,24 @@ static int __init alloc_vectors_page(void)
        sigret_vpage = get_zeroed_page(GFP_ATOMIC);
        if (!sigret_vpage)
                return -ENOMEM;
+#endif
 
 #ifdef CONFIG_KUSER_HELPERS
        kuser_vpage = get_zeroed_page(GFP_ATOMIC);
        if (!kuser_vpage) {
+#ifndef CONFIG_VDSO32
                free_page(sigret_vpage);
+#endif
                return -ENOMEM;
        }
 #endif
 
+#ifndef CONFIG_VDSO32
        /* sigreturn code */
        memcpy((void *)sigret_vpage, __aarch32_sigret_code_start, sigret_sz);
        flush_icache_range(sigret_vpage, sigret_vpage + PAGE_SIZE);
        vectors_page[0] = virt_to_page(sigret_vpage);
+#endif
 
 #ifdef CONFIG_KUSER_HELPERS
        /* kuser helpers */
@@ -115,6 +123,7 @@ static int __init alloc_vectors_page(void)
 }
 arch_initcall(alloc_vectors_page);
 
+#ifndef CONFIG_VDSO32
 int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 {
        struct mm_struct *mm = current->mm;
@@ -149,6 +158,7 @@ out:
 
        return PTR_ERR_OR_ZERO(ret);
 }
+#endif /* !CONFIG_VDSO32 */
 #endif /* CONFIG_COMPAT */
 
 static int __init vdso_mappings_init(const char *name,
@@ -205,6 +215,23 @@ static int __init vdso_mappings_init(const char *name,
        return 0;
 }
 
+#ifdef CONFIG_COMPAT
+#ifdef CONFIG_VDSO32
+
+static struct vdso_mappings vdso32_mappings __ro_after_init;
+
+static int __init vdso32_init(void)
+{
+       extern char vdso32_start[], vdso32_end[];
+
+       return vdso_mappings_init("vdso32", vdso32_start, vdso32_end,
+                                 &vdso32_mappings);
+}
+arch_initcall(vdso32_init);
+
+#endif /* CONFIG_VDSO32 */
+#endif /* CONFIG_COMPAT */
+
 static struct vdso_mappings vdso_mappings __ro_after_init;
 
 static int __init vdso_init(void)
@@ -246,6 +273,33 @@ static int vdso_setup(struct mm_struct *mm,
        return PTR_ERR_OR_ZERO(ret);
 }
 
+#ifdef CONFIG_COMPAT
+#ifdef CONFIG_VDSO32
+int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
+{
+       struct mm_struct *mm = current->mm;
+       void *ret;
+
+       down_write(&mm->mmap_sem);
+
+       ret = ERR_PTR(vdso_setup(mm, &vdso32_mappings));
+#ifdef CONFIG_KUSER_HELPERS
+       if (!IS_ERR(ret))
+               /* Map the kuser helpers at the ABI-defined high address. */
+               ret = _install_special_mapping(mm, AARCH32_KUSER_HELPERS_BASE,
+                                              PAGE_SIZE,
+                                              VM_READ|VM_EXEC|
+                                              VM_MAYREAD|VM_MAYEXEC,
+                                              &compat_vdso_spec[1]);
+#endif
+
+       up_write(&mm->mmap_sem);
+
+       return PTR_ERR_OR_ZERO(ret);
+}
+#endif /* CONFIG_VDSO32 */
+#endif /* CONFIG_COMPAT */
+
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
        struct mm_struct *mm = current->mm;