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Subject[PATCH v7 12/25] arm64: compat: vDSO setup for compat layer
Date
If CONFIG_GENERIC_COMPAT_VDSO is enabled, compat vDSO are installed in a
compat (32 bit) process instead of sigpage.

Add 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>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
---
arch/arm64/kernel/vdso.c | 90 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 88 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index aa1fb25a9fe4..ad3a81b2c7ce 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -40,12 +40,22 @@
#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 */
};
+#ifdef CONFIG_COMPAT_VDSO
+#define VDSO_TYPES (ARM64_VDSO32 + 1)
+#else
#define VDSO_TYPES (ARM64_VDSO + 1)
+#endif /* CONFIG_COMPAT_VDSO */

struct __vdso_abi {
const char *name;
@@ -64,6 +74,13 @@ static struct __vdso_abi vdso_lookup[VDSO_TYPES] __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 */
};

/*
@@ -174,24 +191,52 @@ 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
*/
#define C_VECTORS 0
+#ifdef CONFIG_COMPAT_VDSO
+#define C_VVAR 1
+#define C_VDSO 2
+#define C_PAGES (C_VDSO + 1)
+#else
#define C_SIGPAGE 1
#define C_PAGES (C_SIGPAGE + 1)
+#endif /* CONFIG_COMPAT_VDSO */
static struct page *aarch32_vdso_pages[C_PAGES] __ro_after_init;
-static const struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
+static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
{
.name = "[vectors]", /* ABI */
.pages = &aarch32_vdso_pages[C_VECTORS],
},
+#ifdef CONFIG_COMPAT_VDSO
+ {
+ .name = "[vvar]",
+ },
+ {
+ .name = "[vdso]",
+ .mremap = aarch32_vdso_mremap,
+ },
+#else
{
.name = "[sigpage]", /* ABI */
.pages = &aarch32_vdso_pages[C_SIGPAGE],
},
+#endif /* CONFIG_COMPAT_VDSO */
};

static int aarch32_alloc_kuser_vdso_page(void)
@@ -214,7 +259,33 @@ static int aarch32_alloc_kuser_vdso_page(void)
return 0;
}

-static int __init aarch32_alloc_vdso_pages(void)
+#ifdef CONFIG_COMPAT_VDSO
+static int __aarch32_alloc_vdso_pages(void)
+{
+ int ret;
+
+ vdso_lookup[ARM64_VDSO32].dm = &aarch32_vdso_spec[C_VVAR];
+ vdso_lookup[ARM64_VDSO32].cm = &aarch32_vdso_spec[C_VDSO];
+
+ ret = __vdso_init(ARM64_VDSO32);
+ if (ret)
+ return ret;
+
+ ret = aarch32_alloc_kuser_vdso_page();
+ if (ret) {
+ unsigned long c_vvar =
+ (unsigned long)page_to_virt(aarch32_vdso_pages[C_VVAR]);
+ unsigned long c_vdso =
+ (unsigned long)page_to_virt(aarch32_vdso_pages[C_VDSO]);
+
+ free_page(c_vvar);
+ free_page(c_vdso);
+ }
+
+ return ret;
+}
+#else
+static int __aarch32_alloc_vdso_pages(void)
{
extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
@@ -235,6 +306,12 @@ static int __init aarch32_alloc_vdso_pages(void)

return ret;
}
+#endif /* CONFIG_COMPAT_VDSO */
+
+static int __init aarch32_alloc_vdso_pages(void)
+{
+ return __aarch32_alloc_vdso_pages();
+}
arch_initcall(aarch32_alloc_vdso_pages);

static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
@@ -256,6 +333,7 @@ static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
return PTR_ERR_OR_ZERO(ret);
}

+#ifndef CONFIG_COMPAT_VDSO
static int aarch32_sigreturn_setup(struct mm_struct *mm)
{
unsigned long addr;
@@ -283,6 +361,7 @@ 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)
{
@@ -296,7 +375,14 @@ 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);
--
2.21.0
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