tile: implement gettimeofday() via vDSO
This change creates the framework for vDSO calls, makes the existing
rt_sigreturn() mechanism use it, and adds a fast gettimeofday().
Now that we need to expose the vDSO address to userspace, we add
AT_SYSINFO_EHDR to the set of aux entries provided to userspace.
(You can disable any extra vDSO support by booting with vdso=0,
but the rt_sigreturn vDSO page will still be provided.)
Note that glibc has supported the tile vDSO since release 2.17.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/include/asm/elf.h b/arch/tile/include/asm/elf.h
index ff8a934..31d854f 100644
--- a/arch/tile/include/asm/elf.h
+++ b/arch/tile/include/asm/elf.h
@@ -132,6 +132,11 @@
struct linux_binprm;
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
int executable_stack);
+#define ARCH_DLINFO \
+do { \
+ NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_BASE); \
+} while (0)
+
#ifdef CONFIG_COMPAT
#define COMPAT_ELF_PLATFORM "tilegx-m32"
diff --git a/arch/tile/include/asm/mmu.h b/arch/tile/include/asm/mmu.h
index e2c7890..0cab118 100644
--- a/arch/tile/include/asm/mmu.h
+++ b/arch/tile/include/asm/mmu.h
@@ -22,6 +22,7 @@
* semaphore but atomically, but it is conservatively set.
*/
unsigned long priority_cached;
+ unsigned long vdso_base;
};
typedef struct mm_context mm_context_t;
diff --git a/arch/tile/include/asm/page.h b/arch/tile/include/asm/page.h
index dd033a4..b4f96c0 100644
--- a/arch/tile/include/asm/page.h
+++ b/arch/tile/include/asm/page.h
@@ -39,6 +39,12 @@
#define HPAGE_MASK (~(HPAGE_SIZE - 1))
/*
+ * We do define AT_SYSINFO_EHDR to support vDSO,
+ * but don't use the gate mechanism.
+ */
+#define __HAVE_ARCH_GATE_AREA 1
+
+/*
* If the Kconfig doesn't specify, set a maximum zone order that
* is enough so that we can create huge pages from small pages given
* the respective sizes of the two page types. See <linux/mmzone.h>.
@@ -246,7 +252,7 @@
#endif /* __tilegx__ */
-#ifndef __ASSEMBLY__
+#if !defined(__ASSEMBLY__) && !defined(VDSO_BUILD)
#ifdef CONFIG_HIGHMEM
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index fed1c04..461322b 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -180,10 +180,10 @@
#define TASK_SIZE TASK_SIZE_MAX
#endif
-/* We provide a minimal "vdso" a la x86; just the sigreturn code for now. */
-#define VDSO_BASE (TASK_SIZE - PAGE_SIZE)
+#define VDSO_BASE ((unsigned long)current->active_mm->context.vdso_base)
+#define VDSO_SYM(x) (VDSO_BASE + (unsigned long)(x))
-#define STACK_TOP VDSO_BASE
+#define STACK_TOP TASK_SIZE
/* STACK_TOP_MAX is used temporarily in execve and should not check COMPAT. */
#define STACK_TOP_MAX TASK_SIZE_MAX
diff --git a/arch/tile/include/asm/sections.h b/arch/tile/include/asm/sections.h
index cc95276..5d5d3b7 100644
--- a/arch/tile/include/asm/sections.h
+++ b/arch/tile/include/asm/sections.h
@@ -25,6 +25,10 @@
/* Write-once data is writable only till the end of initialization. */
extern char __w1data_begin[], __w1data_end[];
+extern char vdso_start[], vdso_end[];
+#ifdef CONFIG_COMPAT
+extern char vdso32_start[], vdso32_end[];
+#endif
/* Not exactly sections, but PC comparison points in the code. */
extern char __rt_sigreturn[], __rt_sigreturn_end[];
diff --git a/arch/tile/include/asm/vdso.h b/arch/tile/include/asm/vdso.h
new file mode 100644
index 0000000..9f6a78d
--- /dev/null
+++ b/arch/tile/include/asm/vdso.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * 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, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef __TILE_VDSO_H__
+#define __TILE_VDSO_H__
+
+#include <linux/types.h>
+
+/*
+ * Note about the vdso_data structure:
+ *
+ * NEVER USE THEM IN USERSPACE CODE DIRECTLY. The layout of the
+ * structure is supposed to be known only to the function in the vdso
+ * itself and may change without notice.
+ */
+
+struct vdso_data {
+ __u64 tz_update_count; /* Timezone atomicity ctr */
+ __u64 tb_update_count; /* Timebase atomicity ctr */
+ __u64 xtime_tod_stamp; /* TOD clock for xtime */
+ __u64 xtime_clock_sec; /* Kernel time second */
+ __u64 xtime_clock_nsec; /* Kernel time nanosecond */
+ __u64 wtom_clock_sec; /* Wall to monotonic clock second */
+ __u64 wtom_clock_nsec; /* Wall to monotonic clock nanosecond */
+ __u32 mult; /* Cycle to nanosecond multiplier */
+ __u32 shift; /* Cycle to nanosecond divisor (power of two) */
+ __u32 tz_minuteswest; /* Minutes west of Greenwich */
+ __u32 tz_dsttime; /* Type of dst correction */
+};
+
+extern struct vdso_data *vdso_data;
+
+/* __vdso_rt_sigreturn is defined with the addresses in the vdso page. */
+extern void __vdso_rt_sigreturn(void);
+
+extern int setup_vdso_pages(void);
+
+#endif /* __TILE_VDSO_H__ */
diff --git a/arch/tile/include/uapi/asm/auxvec.h b/arch/tile/include/uapi/asm/auxvec.h
index 1d393ed..c93e927 100644
--- a/arch/tile/include/uapi/asm/auxvec.h
+++ b/arch/tile/include/uapi/asm/auxvec.h
@@ -15,6 +15,7 @@
#ifndef _ASM_TILE_AUXVEC_H
#define _ASM_TILE_AUXVEC_H
-/* No extensions to auxvec */
+/* The vDSO location. */
+#define AT_SYSINFO_EHDR 33
#endif /* _ASM_TILE_AUXVEC_H */