[PATCH v2 19/28] arm64: compat: vDSO setup for compat layer

Vincenzo Frascino
2018-11-29T17:10:46Z

If CONFIG_GENERIC_COMPAT_VDSO is enabled, compat vDSO are installed in a
compat (32 bit) process instead of sigpage.

This patch adds the necessary code to setup the vDSO required pages.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
arch/arm64/kernel/vdso.c | 60 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 59 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index f8020db654db..c36290b46e84 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -40,10 +40,16 @@
#include <asm/vdso.h>

extern char vdso_start[], vdso_end[];
+#ifdef CONFIG_COMPAT_VDSO
+extern char vdso32_start[], vdso32_end[];
+#endif /* CONFIG_COMPAT_VDSO */

/* vdso_lookup arch_index */
enum arch_vdso_type {
ARM64_VDSO = 0,
+#ifdef CONFIG_COMPAT_VDSO
+ ARM64_VDSO32 = 1,
+#endif /* CONFIG_COMPAT_VDSO */
};

struct __vdso_lookup_t {
@@ -63,6 +69,13 @@ static struct __vdso_lookup_t vdso_lookup[2] __ro_after_init = {
.vdso_code_start = vdso_start,
.vdso_code_end = vdso_end,
},
+#ifdef CONFIG_COMPAT_VDSO
+ {
+ .name = "vdso32",
+ .vdso_code_start = vdso32_start,
+ .vdso_code_end = vdso32_end,
+ },
+#endif /* CONFIG_COMPAT_VDSO */
};

/*
@@ -178,23 +191,45 @@ static int __setup_additional_pages(enum arch_vdso_type arch_index,
/*
* Create and map the vectors page for AArch32 tasks.
*/
+#ifdef CONFIG_COMPAT_VDSO
+static int aarch32_vdso_mremap(const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ return __vdso_remap(ARM64_VDSO32, sm, new_vma);
+}
+#endif /* CONFIG_COMPAT_VDSO */
+
/*
* aarch32_vdso_pages:
* 0 - kuser helpers
* 1 - sigreturn code
+ * or (CONFIG_COMPAT_VDSO):
+ * 0 - kuser helpers
+ * 1 - vdso data
+ * 2 - vdso code
*/
static struct page *aarch32_vdso_pages[2] __ro_after_init;
-static struct vm_special_mapping aarch32_vdso_spec[2] __ro_after_init = {
+static struct vm_special_mapping aarch32_vdso_spec[3] __ro_after_init = {
{
/* Must be named [vectors] for compatibility with arm. */
.name = "[vectors]",
.pages = &aarch32_vdso_pages[0],
},
+#ifdef CONFIG_COMPAT_VDSO
+ {
+ .name = "[vvar]",
+ },
+ {
+ .name = "[vdso]",
+ .mremap = aarch32_vdso_mremap,
+ },
+#else
{
/* Must be named [sigpage] for compatibility with arm. */
.name = "[sigpage]",
.pages = &aarch32_vdso_pages[1],
},
+#endif /* CONFIG_COMPAT_VDSO */
};

#ifdef CONFIG_KUSER_HELPERS
@@ -226,6 +261,15 @@ static int aarch32_alloc_kuser_vdso_page(void)
}
#endif /* CONFIG_KUSER_HELPER */

+#ifdef CONFIG_COMPAT_VDSO
+static int aarch32_vdso_init(void)
+{
+ vdso_lookup[ARM64_VDSO32].dm = &aarch32_vdso_spec[1];
+ vdso_lookup[ARM64_VDSO32].cm = &aarch32_vdso_spec[2];
+
+ return __vdso_init(ARM64_VDSO32);
+}
+#else
static int aarch32_alloc_sigreturn_vdso_page(void)
{
extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
@@ -248,11 +292,16 @@ static int aarch32_alloc_sigreturn_vdso_page(void)
return 0;

}
+#endif /* CONFIG_COMPAT_VDSO */

static int __init aarch32_alloc_vdso_pages(void)
{
return aarch32_alloc_kuser_vdso_page() &
+#ifdef CONFIG_COMPAT_VDSO
+ aarch32_vdso_init();
+#else
aarch32_alloc_sigreturn_vdso_page();
+#endif /* CONFIG_COMPAT_VDSO */
}
arch_initcall(aarch32_alloc_vdso_pages);

@@ -277,6 +326,7 @@ static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
}
#endif /* CONFIG_KUSER_HELPERS */

+#ifndef CONFIG_COMPAT_VDSO
static int aarch32_sigreturn_setup(struct mm_struct *mm)
{
unsigned long addr;
@@ -300,6 +350,7 @@ static int aarch32_sigreturn_setup(struct mm_struct *mm)
out:
return PTR_ERR_OR_ZERO(ret);
}
+#endif /* !CONFIG_COMPAT_VDSO */

int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
@@ -313,7 +364,14 @@ int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (ret)
goto out;

+#ifdef CONFIG_COMPAT_VDSO
+ ret = __setup_additional_pages(ARM64_VDSO32,
+ mm,
+ bprm,
+ uses_interp);
+#else
ret = aarch32_sigreturn_setup(mm);
+#endif /* CONFIG_COMPAT_VDSO */

out:
up_write(&mm->mmap_sem);