[PATCH v6 3/6] ARM: miscellaneous vdso infrastructure, preparation
Nathan Lynch
nathan_lynch at mentor.com
Tue Apr 22 17:48:54 PDT 2014
Define the layout of the data structure shared between kernel and
userspace.
Track the vdso address in the mm_context; needed for reporting [vdso]
via /proc/pid/maps and communicating AT_SYSINFO_EHDR to the ELF
loader.
Add declarations for vma_is_vdso, arm_install_vdso, and !CONFIG_VDSO
implementations of same. The CONFIG_VDSO=y implementations of these
come later.
Make arch_vma_name recognize a vdso VMA, using vma_is_vdso to return
"[vdso]" when appropriate.
Define AT_SYSINFO_EHDR, and, if CONFIG_VDSO=y, report the vdso shared
object address via the ELF auxiliary vector.
Note - this adds the AT_SYSINFO_EHDR in a new user-visible header
asm/auxvec.h; this is consistent with other architectures.
Signed-off-by: Nathan Lynch <nathan_lynch at mentor.com>
---
arch/arm/include/asm/Kbuild | 1 -
arch/arm/include/asm/elf.h | 11 +++++++
arch/arm/include/asm/mmu.h | 3 ++
arch/arm/include/asm/vdso.h | 47 ++++++++++++++++++++++++++++
arch/arm/include/asm/vdso_datapage.h | 60 ++++++++++++++++++++++++++++++++++++
arch/arm/include/uapi/asm/Kbuild | 1 +
arch/arm/include/uapi/asm/auxvec.h | 7 +++++
arch/arm/kernel/process.c | 14 +++++++--
8 files changed, 140 insertions(+), 4 deletions(-)
create mode 100644 arch/arm/include/asm/vdso.h
create mode 100644 arch/arm/include/asm/vdso_datapage.h
create mode 100644 arch/arm/include/uapi/asm/auxvec.h
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index 23e728ecf8ab..a0b3a7486488 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -1,6 +1,5 @@
-generic-y += auxvec.h
generic-y += bitsperlong.h
generic-y += cputime.h
generic-y += current.h
diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
index f4b46d39b9cf..45d2ddff662a 100644
--- a/arch/arm/include/asm/elf.h
+++ b/arch/arm/include/asm/elf.h
@@ -1,7 +1,9 @@
#ifndef __ASMARM_ELF_H
#define __ASMARM_ELF_H
+#include <asm/auxvec.h>
#include <asm/hwcap.h>
+#include <asm/vdso_datapage.h>
/*
* ELF register definitions..
@@ -129,6 +131,15 @@ extern unsigned long arch_randomize_brk(struct mm_struct *mm);
#define arch_randomize_brk arch_randomize_brk
#ifdef CONFIG_MMU
+#ifdef CONFIG_VDSO
+#define ARCH_DLINFO \
+do { \
+ /* Account for the data page at the beginning of the [vdso] VMA. */ \
+ NEW_AUX_ENT(AT_SYSINFO_EHDR, \
+ (elf_addr_t)current->mm->context.vdso + \
+ sizeof(union vdso_data_store)); \
+} while (0)
+#endif
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
struct linux_binprm;
int arch_setup_additional_pages(struct linux_binprm *, int);
diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h
index 64fd15159b7d..a5b47421059d 100644
--- a/arch/arm/include/asm/mmu.h
+++ b/arch/arm/include/asm/mmu.h
@@ -11,6 +11,9 @@ typedef struct {
#endif
unsigned int vmalloc_seq;
unsigned long sigpage;
+#ifdef CONFIG_VDSO
+ unsigned long vdso;
+#endif
} mm_context_t;
#ifdef CONFIG_CPU_HAS_ASID
diff --git a/arch/arm/include/asm/vdso.h b/arch/arm/include/asm/vdso.h
new file mode 100644
index 000000000000..0e2a6154eceb
--- /dev/null
+++ b/arch/arm/include/asm/vdso.h
@@ -0,0 +1,47 @@
+#ifndef __ASM_VDSO_H
+#define __ASM_VDSO_H
+
+#ifdef __KERNEL__
+
+#ifndef __ASSEMBLY__
+
+#include <linux/mm_types.h>
+#include <asm/mmu.h>
+
+#ifdef CONFIG_VDSO
+
+static inline bool vma_is_vdso(struct vm_area_struct *vma)
+{
+ if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso)
+ return true;
+ return false;
+}
+
+void arm_install_vdso(struct mm_struct *mm, unsigned long addr);
+
+extern char vdso_start, vdso_end;
+
+extern unsigned long vdso_mapping_len;
+
+#else /* CONFIG_VDSO */
+
+static inline bool vma_is_vdso(struct vm_area_struct *vma)
+{
+ return false;
+}
+
+static inline void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
+{
+}
+
+#define vdso_mapping_len 0
+
+#endif /* CONFIG_VDSO */
+
+#endif /* __ASSEMBLY__ */
+
+#define VDSO_LBASE 0x0
+
+#endif /* __KERNEL__ */
+
+#endif /* __ASM_VDSO_H */
diff --git a/arch/arm/include/asm/vdso_datapage.h b/arch/arm/include/asm/vdso_datapage.h
new file mode 100644
index 000000000000..f08bdb73d3f4
--- /dev/null
+++ b/arch/arm/include/asm/vdso_datapage.h
@@ -0,0 +1,60 @@
+/*
+ * Adapted from arm64 version.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_VDSO_DATAPAGE_H
+#define __ASM_VDSO_DATAPAGE_H
+
+#ifdef __KERNEL__
+
+#ifndef __ASSEMBLY__
+
+#include <asm/page.h>
+
+/* Try to be cache-friendly on systems that don't implement the
+ * generic timer: fit the unconditionally updated fields in the first
+ * 32 bytes.
+ */
+struct vdso_data {
+ u32 seq_count; /* sequence count - odd during updates */
+ u16 use_syscall; /* whether to fall back to syscalls */
+ u16 cs_shift; /* clocksource shift */
+ u32 xtime_coarse_sec; /* coarse time */
+ u32 xtime_coarse_nsec;
+
+ u32 wtm_clock_sec; /* wall to monotonic offset */
+ u32 wtm_clock_nsec;
+ u32 xtime_clock_sec; /* CLOCK_REALTIME - seconds */
+ u32 cs_mult; /* clocksource multiplier */
+
+ u64 cs_cycle_last; /* last cycle value */
+ u64 cs_mask; /* clocksource mask */
+
+ u64 xtime_clock_snsec; /* CLOCK_REALTIME sub-ns base */
+ u32 tz_minuteswest; /* timezone info for gettimeofday(2) */
+ u32 tz_dsttime;
+};
+
+union vdso_data_store {
+ struct vdso_data data;
+ u8 page[PAGE_SIZE];
+};
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __KERNEL__ */
+
+#endif /* __ASM_VDSO_DATAPAGE_H */
diff --git a/arch/arm/include/uapi/asm/Kbuild b/arch/arm/include/uapi/asm/Kbuild
index 70a1c9da30ca..a1c05f93d920 100644
--- a/arch/arm/include/uapi/asm/Kbuild
+++ b/arch/arm/include/uapi/asm/Kbuild
@@ -1,6 +1,7 @@
# UAPI Header export list
include include/uapi/asm-generic/Kbuild.asm
+header-y += auxvec.h
header-y += byteorder.h
header-y += fcntl.h
header-y += hwcap.h
diff --git a/arch/arm/include/uapi/asm/auxvec.h b/arch/arm/include/uapi/asm/auxvec.h
new file mode 100644
index 000000000000..f56936b97ec2
--- /dev/null
+++ b/arch/arm/include/uapi/asm/auxvec.h
@@ -0,0 +1,7 @@
+#ifndef __ASM_AUXVEC_H
+#define __ASM_AUXVEC_H
+
+/* vDSO location */
+#define AT_SYSINFO_EHDR 33
+
+#endif
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 219a0d1d10fc..40445fb71ac9 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -41,6 +41,7 @@
#include <asm/system_misc.h>
#include <asm/mach/time.h>
#include <asm/tls.h>
+#include <asm/vdso.h>
#ifdef CONFIG_CC_STACKPROTECTOR
#include <linux/stackprotector.h>
@@ -472,9 +473,16 @@ int in_gate_area_no_mm(unsigned long addr)
const char *arch_vma_name(struct vm_area_struct *vma)
{
- return is_gate_vma(vma) ? "[vectors]" :
- (vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage) ?
- "[sigpage]" : NULL;
+ if (is_gate_vma(vma))
+ return "[vectors]";
+
+ if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage)
+ return "[sigpage]";
+
+ if (vma_is_vdso(vma))
+ return "[vdso]";
+
+ return NULL;
}
static unsigned long vdso_addr(const struct mm_struct *mm, unsigned int npages)
--
1.8.3.1
More information about the linux-arm-kernel
mailing list