[PATCH v9 4/6] ARM: add vdso user-space code
Nathan Lynch
nathan_lynch at mentor.com
Fri Aug 22 14:52:29 PDT 2014
Place vdso-related user-space code in arch/arm/kernel/vdso/.
It is almost completely written in C with some assembly helpers to
load the data page address, sample the counter, and fall back to
system calls when necessary.
If CONFIG_ARM_ARCH_TIMER is not enabled, the vdso cannot service
high-resolution clocks and falls back to syscalls. Low-resolution
clocks e.g. CLOCK_REALTIME_COARSE can be serviced regardless.
Of particular note is that a post-processing step ("vdsomunge") is
necessary to produce a shared object which is architecturally allowed
to be used by both soft- and hard-float EABI programs.
The 2012 edition of the ARM ABI defines Tag_ABI_VFP_args = 3 "Code is
compatible with both the base and VFP variants; the user did not
permit non-variadic functions to pass FP parameters/results."
Unfortunately current toolchains do not support this tag, which is
ideally what we would use.
The best available option is to ensure that both EF_ARM_ABI_FLOAT_SOFT
and EF_ARM_ABI_FLOAT_HARD are unset in the ELF header's e_flags,
indicating that the shared object is "old" and should be accepted for
backward compatibility's sake. While binutils < 2.24 appear to
produce a vdso.so with both flags clear, 2.24 always sets
EF_ARM_ABI_FLOAT_SOFT, with no way to inhibit this behavior. So we
have to fix things up with a custom post-processing step.
In fact, the VDSO code in glibc does much less validation (including
checking these flags) than the code for handling conventional
file-backed shared libraries, so this is a bit moot unless glibc's
VDSO code becomes more strict.
Signed-off-by: Nathan Lynch <nathan_lynch at mentor.com>
---
arch/arm/kernel/asm-offsets.c | 5 +
arch/arm/vdso/.gitignore | 1 +
arch/arm/vdso/Makefile | 74 ++++++++++
arch/arm/vdso/datapage.S | 15 ++
arch/arm/vdso/vdso.S | 35 +++++
arch/arm/vdso/vdso.lds.S | 88 ++++++++++++
arch/arm/vdso/vdsomunge.c | 208 +++++++++++++++++++++++++++
arch/arm/vdso/vgettimeofday.c | 320 ++++++++++++++++++++++++++++++++++++++++++
8 files changed, 746 insertions(+)
create mode 100644 arch/arm/vdso/.gitignore
create mode 100644 arch/arm/vdso/Makefile
create mode 100644 arch/arm/vdso/datapage.S
create mode 100644 arch/arm/vdso/vdso.S
create mode 100644 arch/arm/vdso/vdso.lds.S
create mode 100644 arch/arm/vdso/vdsomunge.c
create mode 100644 arch/arm/vdso/vgettimeofday.c
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 713e807621d2..72b4c3873dc8 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -24,6 +24,7 @@
#include <asm/memory.h>
#include <asm/procinfo.h>
#include <asm/suspend.h>
+#include <asm/vdso_datapage.h>
#include <asm/hardware/cache-l2x0.h>
#include <linux/kbuild.h>
@@ -200,5 +201,9 @@ int main(void)
#endif
DEFINE(KVM_VTTBR, offsetof(struct kvm, arch.vttbr));
#endif
+ BLANK();
+#ifdef CONFIG_VDSO
+ DEFINE(VDSO_DATA_SIZE, sizeof(union vdso_data_store));
+#endif
return 0;
}
diff --git a/arch/arm/vdso/.gitignore b/arch/arm/vdso/.gitignore
new file mode 100644
index 000000000000..f8b69d84238e
--- /dev/null
+++ b/arch/arm/vdso/.gitignore
@@ -0,0 +1 @@
+vdso.lds
diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
new file mode 100644
index 000000000000..bab0a8be7924
--- /dev/null
+++ b/arch/arm/vdso/Makefile
@@ -0,0 +1,74 @@
+hostprogs-y := vdsomunge
+
+obj-vdso := vgettimeofday.o datapage.o
+
+# Build rules
+targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.so.raw vdso.lds
+obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
+
+ccflags-y := -shared -fPIC -fno-common -fno-builtin -fno-stack-protector
+ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 -DDISABLE_BRANCH_PROFILING
+ccflags-y += -Wl,--no-undefined $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
+
+obj-y += vdso.o
+extra-y += vdso.lds
+CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
+
+CFLAGS_REMOVE_vdso.o = -pg
+
+# Force -O2 to avoid libgcc dependencies
+CFLAGS_REMOVE_vgettimeofday.o = -pg -Os
+CFLAGS_vgettimeofday.o = -O2
+
+# Disable gcov profiling for VDSO code
+GCOV_PROFILE := n
+
+# Force dependency
+$(obj)/vdso.o : $(obj)/vdso.so
+
+# Link rule for the .so file
+$(obj)/vdso.so.raw: $(src)/vdso.lds $(obj-vdso) FORCE
+ $(call if_changed,vdsold)
+
+$(obj)/vdso.so.dbg: $(obj)/vdso.so.raw $(obj)/vdsomunge FORCE
+ $(call if_changed,vdsomunge)
+
+# Strip rule for the .so file
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg FORCE
+ $(call if_changed,objcopy)
+
+# Actual build commands
+quiet_cmd_vdsold = VDSO $@
+ cmd_vdsold = $(CC) $(c_flags) -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) \
+ $(call cc-ldoption, -Wl$(comma)--build-id) \
+ -Wl,-Bsymbolic -Wl,-z,max-page-size=4096 \
+ -Wl,-z,common-page-size=4096 -o $@
+
+quiet_cmd_vdsomunge = MUNGE $@
+ cmd_vdsomunge = $(objtree)/$(obj)/vdsomunge $< $@
+
+#
+# Install the unstripped copy of vdso.so.dbg. If our toolchain
+# supports build-id, install .build-id links as well.
+#
+# Cribbed from arch/x86/vdso/Makefile.
+#
+quiet_cmd_vdso_install = INSTALL $<
+define cmd_vdso_install
+ cp $< "$(MODLIB)/vdso/vdso.so"; \
+ if readelf -n $< | grep -q 'Build ID'; then \
+ buildid=`readelf -n $< |grep 'Build ID' |sed -e 's/^.*Build ID: \(.*\)$$/\1/'`; \
+ first=`echo $$buildid | cut -b-2`; \
+ last=`echo $$buildid | cut -b3-`; \
+ mkdir -p "$(MODLIB)/vdso/.build-id/$$first"; \
+ ln -sf "../../vdso.so" "$(MODLIB)/vdso/.build-id/$$first/$$last.debug"; \
+ fi
+endef
+
+$(MODLIB)/vdso: FORCE
+ @mkdir -p $(MODLIB)/vdso
+
+PHONY += vdso_install
+vdso_install: $(obj)/vdso.so.dbg $(MODLIB)/vdso FORCE
+ $(call cmd,vdso_install)
diff --git a/arch/arm/vdso/datapage.S b/arch/arm/vdso/datapage.S
new file mode 100644
index 000000000000..a2e60367931b
--- /dev/null
+++ b/arch/arm/vdso/datapage.S
@@ -0,0 +1,15 @@
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+
+ .align 2
+.L_vdso_data_ptr:
+ .long _start - . - VDSO_DATA_SIZE
+
+ENTRY(__get_datapage)
+ .fnstart
+ adr r0, .L_vdso_data_ptr
+ ldr r1, [r0]
+ add r0, r0, r1
+ bx lr
+ .fnend
+ENDPROC(__get_datapage)
diff --git a/arch/arm/vdso/vdso.S b/arch/arm/vdso/vdso.S
new file mode 100644
index 000000000000..b2b97e3e7bab
--- /dev/null
+++ b/arch/arm/vdso/vdso.S
@@ -0,0 +1,35 @@
+/*
+ * 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/>.
+ *
+ * Author: Will Deacon <will.deacon at arm.com>
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <linux/const.h>
+#include <asm/page.h>
+
+ __PAGE_ALIGNED_DATA
+
+ .globl vdso_start, vdso_end
+ .balign PAGE_SIZE
+vdso_start:
+ .incbin "arch/arm/vdso/vdso.so"
+ .balign PAGE_SIZE
+vdso_end:
+
+ .previous
diff --git a/arch/arm/vdso/vdso.lds.S b/arch/arm/vdso/vdso.lds.S
new file mode 100644
index 000000000000..dabdebcab17e
--- /dev/null
+++ b/arch/arm/vdso/vdso.lds.S
@@ -0,0 +1,88 @@
+/*
+ * Adapted from arm64 version.
+ *
+ * GNU linker script for the VDSO library.
+ *
+ * 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/>.
+ *
+ * Author: Will Deacon <will.deacon at arm.com>
+ * Heavily based on the vDSO linker scripts for other archs.
+ */
+
+#include <linux/const.h>
+#include <asm/page.h>
+#include <asm/vdso.h>
+
+OUTPUT_FORMAT("elf32-littlearm", "elf32-bigarm", "elf32-littlearm")
+OUTPUT_ARCH(arm)
+
+SECTIONS
+{
+ PROVIDE(_start = .);
+
+ . = VDSO_LBASE + SIZEOF_HEADERS;
+
+ .hash : { *(.hash) } :text
+ .gnu.hash : { *(.gnu.hash) }
+ .dynsym : { *(.dynsym) }
+ .dynstr : { *(.dynstr) }
+ .gnu.version : { *(.gnu.version) }
+ .gnu.version_d : { *(.gnu.version_d) }
+ .gnu.version_r : { *(.gnu.version_r) }
+
+ .note : { *(.note.*) } :text :note
+
+
+ .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
+ .eh_frame : { KEEP (*(.eh_frame)) } :text
+
+ .dynamic : { *(.dynamic) } :text :dynamic
+
+ .rodata : { *(.rodata*) } :text
+
+ .text : { *(.text*) } :text =0xe7f001f2
+
+ .got : { *(.got) }
+ .rel.plt : { *(.rel.plt) }
+
+ /DISCARD/ : {
+ *(.note.GNU-stack)
+ *(.data .data.* .gnu.linkonce.d.* .sdata*)
+ *(.bss .sbss .dynbss .dynsbss)
+ }
+}
+
+/*
+ * We must supply the ELF program headers explicitly to get just one
+ * PT_LOAD segment, and set the flags explicitly to make segments read-only.
+ */
+PHDRS
+{
+ text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
+ dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
+ note PT_NOTE FLAGS(4); /* PF_R */
+ eh_frame_hdr PT_GNU_EH_FRAME;
+}
+
+VERSION
+{
+ LINUX_2.6 {
+ global:
+ __vdso_clock_getres;
+ __vdso_clock_gettime;
+ __vdso_gettimeofday;
+ local: *;
+ };
+}
diff --git a/arch/arm/vdso/vdsomunge.c b/arch/arm/vdso/vdsomunge.c
new file mode 100644
index 000000000000..b586ef699fb8
--- /dev/null
+++ b/arch/arm/vdso/vdsomunge.c
@@ -0,0 +1,208 @@
+/*
+ * Copyright 2014 Mentor Graphics Corporation.
+ *
+ * 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 of the
+ * License.
+ *
+ * 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/>.
+ *
+ *
+ * vdsomunge - Host program which produces a shared object
+ * architecturally specified to be usable by both soft- and hard-float
+ * programs.
+ *
+ * The Procedure Call Standard for the ARM Architecture (ARM IHI
+ * 0042E) says:
+ *
+ * 6.4.1 VFP and Base Standard Compatibility
+ *
+ * Code compiled for the VFP calling standard is compatible with
+ * the base standard (and vice-versa) if no floating-point or
+ * containerized vector arguments or results are used.
+ *
+ * And ELF for the ARM Architecture (ARM IHI 0044E) (Table 4-2) says:
+ *
+ * If both EF_ARM_ABI_FLOAT_XXXX bits are clear, conformance to the
+ * base procedure-call standard is implied.
+ *
+ * The VDSO is built with -msoft-float, as with the rest of the ARM
+ * kernel, and uses no floating point arguments or results. The build
+ * process will produce a shared object that may or may not have the
+ * EF_ARM_ABI_FLOAT_SOFT flag set (it seems to depend on the binutils
+ * version; binutils starting with 2.24 appears to set it). The
+ * EF_ARM_ABI_FLOAT_HARD flag should definitely not be set, and this
+ * program will error out if it is.
+ *
+ * If the soft-float flag is set, this program clears it. That's all
+ * it does.
+ */
+
+#define _GNU_SOURCE
+
+#include <byteswap.h>
+#include <elf.h>
+#include <errno.h>
+#include <error.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define HOST_ORDER ELFDATA2LSB
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define HOST_ORDER ELFDATA2MSB
+#endif
+
+/* Some of the ELF constants we'd like to use were added to <elf.h>
+ * relatively recently.
+ */
+#ifndef EF_ARM_EABI_VER5
+#define EF_ARM_EABI_VER5 0x05000000
+#endif
+
+#ifndef EF_ARM_ABI_FLOAT_SOFT
+#define EF_ARM_ABI_FLOAT_SOFT 0x200
+#endif
+
+#ifndef EF_ARM_ABI_FLOAT_HARD
+#define EF_ARM_ABI_FLOAT_HARD 0x400
+#endif
+
+static const char *outfile;
+
+static void cleanup(void)
+{
+ if (error_message_count > 0 && outfile != NULL)
+ unlink(outfile);
+}
+
+static Elf32_Word read_elf_word(Elf32_Word word, bool swap)
+{
+ return swap ? bswap_32(word) : word;
+}
+
+static Elf32_Half read_elf_half(Elf32_Half half, bool swap)
+{
+ return swap ? bswap_16(half) : half;
+}
+
+static void write_elf_word(Elf32_Word val, Elf32_Word *dst, bool swap)
+{
+ *dst = swap ? bswap_32(val) : val;
+}
+
+int main(int argc, char **argv)
+{
+ const Elf32_Ehdr *inhdr;
+ bool clear_soft_float;
+ const char *infile;
+ Elf32_Word e_flags;
+ const void *inbuf;
+ struct stat stat;
+ void *outbuf;
+ bool swap;
+ int outfd;
+ int infd;
+
+ atexit(cleanup);
+
+ if (argc != 3)
+ error(EXIT_FAILURE, 0, "Usage: %s [infile] [outfile]", argv[0]);
+
+ infile = argv[1];
+ outfile = argv[2];
+
+ infd = open(infile, O_RDONLY);
+ if (infd < 0)
+ error(EXIT_FAILURE, errno, "Cannot open %s", infile);
+
+ if (fstat(infd, &stat) != 0)
+ error(EXIT_FAILURE, errno, "Failed stat for %s", infile);
+
+ inbuf = mmap(NULL, stat.st_size, PROT_READ, MAP_PRIVATE, infd, 0);
+ if (inbuf == MAP_FAILED)
+ error(EXIT_FAILURE, errno, "Failed to map %s", infile);
+
+ close(infd);
+
+ inhdr = inbuf;
+
+ if (memcmp(&inhdr->e_ident, ELFMAG, SELFMAG) != 0)
+ error(EXIT_FAILURE, 0, "Not an ELF file");
+
+ if (inhdr->e_ident[EI_CLASS] != ELFCLASS32)
+ error(EXIT_FAILURE, 0, "Unsupported ELF class");
+
+ swap = inhdr->e_ident[EI_DATA] != HOST_ORDER;
+
+ if (read_elf_half(inhdr->e_type, swap) != ET_DYN)
+ error(EXIT_FAILURE, 0, "Not a shared object");
+
+ if (read_elf_half(inhdr->e_machine, swap) != EM_ARM) {
+ error(EXIT_FAILURE, 0, "Unsupported architecture %#x",
+ inhdr->e_machine);
+ }
+
+ e_flags = read_elf_word(inhdr->e_flags, swap);
+
+ if (EF_ARM_EABI_VERSION(e_flags) != EF_ARM_EABI_VER5) {
+ error(EXIT_FAILURE, 0, "Unsupported EABI version %#x",
+ EF_ARM_EABI_VERSION(e_flags));
+ }
+
+ if (e_flags & EF_ARM_ABI_FLOAT_HARD)
+ error(EXIT_FAILURE, 0, "Unexpected hard-float flag set in "
+ "e_flags");
+
+ clear_soft_float = !!(e_flags & EF_ARM_ABI_FLOAT_SOFT);
+
+ outfd = open(outfile, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
+ if (outfd < 0)
+ error(EXIT_FAILURE, errno, "Cannot open %s", outfile);
+
+ if (ftruncate(outfd, stat.st_size) != 0)
+ error(EXIT_FAILURE, errno, "Cannot truncate %s", outfile);
+
+ outbuf = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED,
+ outfd, 0);
+ if (outbuf == MAP_FAILED)
+ error(EXIT_FAILURE, errno, "Failed to map %s", outfile);
+
+ close(outfd);
+
+ memcpy(outbuf, inbuf, stat.st_size);
+
+ if (clear_soft_float) {
+ Elf32_Ehdr *outhdr;
+
+ outhdr = outbuf;
+ e_flags &= ~EF_ARM_ABI_FLOAT_SOFT;
+ write_elf_word(e_flags, &outhdr->e_flags, swap);
+
+#ifdef DEBUG
+ printf("%s: cleared soft-float bit in ELF header for %s "
+ "(%#x => %#x)\n", program_invocation_short_name,
+ outfile, inhdr->e_flags, outhdr->e_flags);
+#endif
+
+ }
+
+ if (msync(outbuf, stat.st_size, MS_SYNC) != 0)
+ error(EXIT_FAILURE, errno, "Failed to sync %s", outfile);
+
+ return EXIT_SUCCESS;
+}
diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c
new file mode 100644
index 000000000000..cb3201b6cd71
--- /dev/null
+++ b/arch/arm/vdso/vgettimeofday.c
@@ -0,0 +1,320 @@
+/*
+ * Copyright 2014 Mentor Graphics Corporation.
+ *
+ * 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 of the
+ * License.
+ *
+ * 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/>.
+ */
+
+#include <linux/compiler.h>
+#include <linux/hrtimer.h>
+#include <linux/time.h>
+#include <asm/arch_timer.h>
+#include <asm/barrier.h>
+#include <asm/bug.h>
+#include <asm/page.h>
+#include <asm/unistd.h>
+#include <asm/vdso_datapage.h>
+
+#ifndef CONFIG_AEABI
+#error This code depends on AEABI system call conventions
+#endif
+
+extern struct vdso_data *__get_datapage(void);
+
+static u32 __vdso_read_begin(const struct vdso_data *vdata)
+{
+ u32 seq;
+repeat:
+ seq = ACCESS_ONCE(vdata->seq_count);
+ if (seq & 1) {
+ cpu_relax();
+ goto repeat;
+ }
+ return seq;
+}
+
+static u32 vdso_read_begin(const struct vdso_data *vdata)
+{
+ u32 seq = __vdso_read_begin(vdata);
+ smp_rmb();
+ return seq;
+}
+
+static int vdso_read_retry(const struct vdso_data *vdata, u32 start)
+{
+ smp_rmb();
+ return vdata->seq_count != start;
+}
+
+static long clock_gettime_fallback(clockid_t _clkid, struct timespec *_ts)
+{
+ register struct timespec *ts asm("r1") = _ts;
+ register clockid_t clkid asm("r0") = _clkid;
+ register long ret asm ("r0");
+ register long nr asm("r7") = __NR_clock_gettime;
+
+ asm volatile(
+ " swi #0\n"
+ : "=r" (ret)
+ : "r" (clkid), "r" (ts), "r" (nr)
+ : "memory");
+
+ return ret;
+}
+
+static int do_realtime_coarse(struct timespec *ts, struct vdso_data *vdata)
+{
+ u32 seq;
+
+ do {
+ seq = vdso_read_begin(vdata);
+
+ ts->tv_sec = vdata->xtime_coarse_sec;
+ ts->tv_nsec = vdata->xtime_coarse_nsec;
+
+ } while (vdso_read_retry(vdata, seq));
+
+ return 0;
+}
+
+static int do_monotonic_coarse(struct timespec *ts, struct vdso_data *vdata)
+{
+ struct timespec tomono;
+ u32 seq;
+
+ do {
+ seq = vdso_read_begin(vdata);
+
+ ts->tv_sec = vdata->xtime_coarse_sec;
+ ts->tv_nsec = vdata->xtime_coarse_nsec;
+
+ tomono.tv_sec = vdata->wtm_clock_sec;
+ tomono.tv_nsec = vdata->wtm_clock_nsec;
+
+ } while (vdso_read_retry(vdata, seq));
+
+ ts->tv_sec += tomono.tv_sec;
+ timespec_add_ns(ts, tomono.tv_nsec);
+
+ return 0;
+}
+
+#ifdef CONFIG_ARM_ARCH_TIMER
+
+static u64 get_ns(struct vdso_data *vdata)
+{
+ u64 cycle_delta;
+ u64 cycle_now;
+ u64 nsec;
+
+ cycle_now = arch_counter_get_cntvct();
+
+ cycle_delta = (cycle_now - vdata->cs_cycle_last) & vdata->cs_mask;
+
+ nsec = (cycle_delta * vdata->cs_mult) + vdata->xtime_clock_snsec;
+ nsec >>= vdata->cs_shift;
+
+ return nsec;
+}
+
+static int do_realtime(struct timespec *ts, struct vdso_data *vdata)
+{
+ u64 nsecs;
+ u32 seq;
+
+ do {
+ seq = vdso_read_begin(vdata);
+
+ if (vdata->use_syscall)
+ return -1;
+
+ ts->tv_sec = vdata->xtime_clock_sec;
+ nsecs = get_ns(vdata);
+
+ } while (vdso_read_retry(vdata, seq));
+
+ ts->tv_nsec = 0;
+ timespec_add_ns(ts, nsecs);
+
+ return 0;
+}
+
+static int do_monotonic(struct timespec *ts, struct vdso_data *vdata)
+{
+ struct timespec tomono;
+ u64 nsecs;
+ u32 seq;
+
+ do {
+ seq = vdso_read_begin(vdata);
+
+ if (vdata->use_syscall)
+ return -1;
+
+ ts->tv_sec = vdata->xtime_clock_sec;
+ nsecs = get_ns(vdata);
+
+ tomono.tv_sec = vdata->wtm_clock_sec;
+ tomono.tv_nsec = vdata->wtm_clock_nsec;
+
+ } while (vdso_read_retry(vdata, seq));
+
+ ts->tv_sec += tomono.tv_sec;
+ ts->tv_nsec = 0;
+ timespec_add_ns(ts, nsecs + tomono.tv_nsec);
+
+ return 0;
+}
+
+#else /* CONFIG_ARM_ARCH_TIMER */
+
+static int do_realtime(struct timespec *ts, struct vdso_data *vdata)
+{
+ return -1;
+}
+
+static int do_monotonic(struct timespec *ts, struct vdso_data *vdata)
+{
+ return -1;
+}
+
+#endif /* CONFIG_ARM_ARCH_TIMER */
+
+int __vdso_clock_gettime(clockid_t clkid, struct timespec *ts)
+{
+ struct vdso_data *vdata;
+ int ret = -1;
+
+ vdata = __get_datapage();
+
+ switch (clkid) {
+ case CLOCK_REALTIME_COARSE:
+ ret = do_realtime_coarse(ts, vdata);
+ break;
+ case CLOCK_MONOTONIC_COARSE:
+ ret = do_monotonic_coarse(ts, vdata);
+ break;
+ case CLOCK_REALTIME:
+ ret = do_realtime(ts, vdata);
+ break;
+ case CLOCK_MONOTONIC:
+ ret = do_monotonic(ts, vdata);
+ break;
+ default:
+ break;
+ }
+
+ if (ret)
+ ret = clock_gettime_fallback(clkid, ts);
+
+ return ret;
+}
+
+static long clock_getres_fallback(clockid_t _clkid, struct timespec *_ts)
+{
+ register struct timespec *ts asm("r1") = _ts;
+ register clockid_t clkid asm("r0") = _clkid;
+ register long ret asm ("r0");
+ register long nr asm("r7") = __NR_clock_getres;
+
+ asm volatile(
+ " swi #0\n"
+ : "=r" (ret)
+ : "r" (clkid), "r" (ts), "r" (nr)
+ : "memory");
+
+ return ret;
+}
+
+int __vdso_clock_getres(clockid_t clkid, struct timespec *ts)
+{
+ int ret;
+
+ switch (clkid) {
+ case CLOCK_REALTIME:
+ case CLOCK_MONOTONIC:
+ if (ts) {
+ ts->tv_sec = 0;
+ ts->tv_nsec = MONOTONIC_RES_NSEC;
+ }
+ ret = 0;
+ break;
+ case CLOCK_REALTIME_COARSE:
+ case CLOCK_MONOTONIC_COARSE:
+ if (ts) {
+ ts->tv_sec = 0;
+ ts->tv_nsec = LOW_RES_NSEC;
+ }
+ ret = 0;
+ break;
+ default:
+ ret = clock_getres_fallback(clkid, ts);
+ break;
+ }
+
+ return ret;
+}
+
+static long gettimeofday_fallback(struct timeval *_tv, struct timezone *_tz)
+{
+ register struct timezone *tz asm("r1") = _tz;
+ register struct timeval *tv asm("r0") = _tv;
+ register long ret asm ("r0");
+ register long nr asm("r7") = __NR_gettimeofday;
+
+ asm volatile(
+ " swi #0\n"
+ : "=r" (ret)
+ : "r" (tv), "r" (tz), "r" (nr)
+ : "memory");
+
+ return ret;
+}
+
+int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
+{
+ struct timespec ts;
+ struct vdso_data *vdata;
+ int ret;
+
+ vdata = __get_datapage();
+
+ ret = do_realtime(&ts, vdata);
+ if (ret)
+ return gettimeofday_fallback(tv, tz);
+
+ if (tv) {
+ tv->tv_sec = ts.tv_sec;
+ tv->tv_usec = ts.tv_nsec / 1000;
+ }
+ if (tz) {
+ tz->tz_minuteswest = vdata->tz_minuteswest;
+ tz->tz_dsttime = vdata->tz_dsttime;
+ }
+
+ return ret;
+}
+
+/* Avoid unresolved references emitted by GCC */
+
+void __aeabi_unwind_cpp_pr0(void)
+{
+}
+
+void __aeabi_unwind_cpp_pr1(void)
+{
+}
+
+void __aeabi_unwind_cpp_pr2(void)
+{
+}
--
1.9.3
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