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authorArnd Bergmann <arnd@arndb.de>2012-10-04 22:57:00 +0200
committerArnd Bergmann <arnd@arndb.de>2012-10-04 22:57:51 +0200
commitc37d6154c0b9163c27e53cc1d0be3867b4abd760 (patch)
tree7a24522c56d1cb284dff1d3c225bbdaba0901bb5 /arch/arm64/kernel/vdso/gettimeofday.S
parente7a570ff7dff9af6e54ff5e580a61ec7652137a0 (diff)
parent8a1ab3155c2ac7fbe5f2038d6e26efeb607a1498 (diff)
Merge branch 'disintegrate-asm-generic' of git://git.infradead.org/users/dhowells/linux-headers into asm-generic
Patches from David Howells <dhowells@redhat.com>: This is to complete part of the UAPI disintegration for which the preparatory patches were pulled recently. Note that there are some fixup patches which are at the base of the branch aimed at you, plus all arches get the asm-generic branch merged in too. * 'disintegrate-asm-generic' of git://git.infradead.org/users/dhowells/linux-headers: UAPI: (Scripted) Disintegrate include/asm-generic UAPI: Fix conditional header installation handling (notably kvm_para.h on m68k) c6x: remove c6x signal.h UAPI: Split compound conditionals containing __KERNEL__ in Arm64 UAPI: Fix the guards on various asm/unistd.h files Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/arm64/kernel/vdso/gettimeofday.S')
-rw-r--r--arch/arm64/kernel/vdso/gettimeofday.S242
1 files changed, 242 insertions, 0 deletions
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
new file mode 100644
index 00000000000..dcb8c203a3b
--- /dev/null
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -0,0 +1,242 @@
+/*
+ * Userspace implementations of gettimeofday() and friends.
+ *
+ * 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@arm.com>
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+
+#define NSEC_PER_SEC_LO16 0xca00
+#define NSEC_PER_SEC_HI16 0x3b9a
+
+vdso_data .req x6
+use_syscall .req w7
+seqcnt .req w8
+
+ .macro seqcnt_acquire
+9999: ldr seqcnt, [vdso_data, #VDSO_TB_SEQ_COUNT]
+ tbnz seqcnt, #0, 9999b
+ dmb ishld
+ ldr use_syscall, [vdso_data, #VDSO_USE_SYSCALL]
+ .endm
+
+ .macro seqcnt_read, cnt
+ dmb ishld
+ ldr \cnt, [vdso_data, #VDSO_TB_SEQ_COUNT]
+ .endm
+
+ .macro seqcnt_check, cnt, fail
+ cmp \cnt, seqcnt
+ b.ne \fail
+ .endm
+
+ .text
+
+/* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); */
+ENTRY(__kernel_gettimeofday)
+ .cfi_startproc
+ mov x2, x30
+ .cfi_register x30, x2
+
+ /* Acquire the sequence counter and get the timespec. */
+ adr vdso_data, _vdso_data
+1: seqcnt_acquire
+ cbnz use_syscall, 4f
+
+ /* If tv is NULL, skip to the timezone code. */
+ cbz x0, 2f
+ bl __do_get_tspec
+ seqcnt_check w13, 1b
+
+ /* Convert ns to us. */
+ mov x11, #1000
+ udiv x10, x10, x11
+ stp x9, x10, [x0, #TVAL_TV_SEC]
+2:
+ /* If tz is NULL, return 0. */
+ cbz x1, 3f
+ ldp w4, w5, [vdso_data, #VDSO_TZ_MINWEST]
+ seqcnt_read w13
+ seqcnt_check w13, 1b
+ stp w4, w5, [x1, #TZ_MINWEST]
+3:
+ mov x0, xzr
+ ret x2
+4:
+ /* Syscall fallback. */
+ mov x8, #__NR_gettimeofday
+ svc #0
+ ret x2
+ .cfi_endproc
+ENDPROC(__kernel_gettimeofday)
+
+/* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp); */
+ENTRY(__kernel_clock_gettime)
+ .cfi_startproc
+ cmp w0, #CLOCK_REALTIME
+ ccmp w0, #CLOCK_MONOTONIC, #0x4, ne
+ b.ne 2f
+
+ mov x2, x30
+ .cfi_register x30, x2
+
+ /* Get kernel timespec. */
+ adr vdso_data, _vdso_data
+1: seqcnt_acquire
+ cbnz use_syscall, 7f
+
+ bl __do_get_tspec
+ seqcnt_check w13, 1b
+
+ cmp w0, #CLOCK_MONOTONIC
+ b.ne 6f
+
+ /* Get wtm timespec. */
+ ldp x14, x15, [vdso_data, #VDSO_WTM_CLK_SEC]
+
+ /* Check the sequence counter. */
+ seqcnt_read w13
+ seqcnt_check w13, 1b
+ b 4f
+2:
+ cmp w0, #CLOCK_REALTIME_COARSE
+ ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
+ b.ne 8f
+
+ /* Get coarse timespec. */
+ adr vdso_data, _vdso_data
+3: seqcnt_acquire
+ ldp x9, x10, [vdso_data, #VDSO_XTIME_CRS_SEC]
+
+ cmp w0, #CLOCK_MONOTONIC_COARSE
+ b.ne 6f
+
+ /* Get wtm timespec. */
+ ldp x14, x15, [vdso_data, #VDSO_WTM_CLK_SEC]
+
+ /* Check the sequence counter. */
+ seqcnt_read w13
+ seqcnt_check w13, 3b
+4:
+ /* Add on wtm timespec. */
+ add x9, x9, x14
+ add x10, x10, x15
+
+ /* Normalise the new timespec. */
+ mov x14, #NSEC_PER_SEC_LO16
+ movk x14, #NSEC_PER_SEC_HI16, lsl #16
+ cmp x10, x14
+ b.lt 5f
+ sub x10, x10, x14
+ add x9, x9, #1
+5:
+ cmp x10, #0
+ b.ge 6f
+ add x10, x10, x14
+ sub x9, x9, #1
+
+6: /* Store to the user timespec. */
+ stp x9, x10, [x1, #TSPEC_TV_SEC]
+ mov x0, xzr
+ ret x2
+7:
+ mov x30, x2
+8: /* Syscall fallback. */
+ mov x8, #__NR_clock_gettime
+ svc #0
+ ret
+ .cfi_endproc
+ENDPROC(__kernel_clock_gettime)
+
+/* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */
+ENTRY(__kernel_clock_getres)
+ .cfi_startproc
+ cbz w1, 3f
+
+ cmp w0, #CLOCK_REALTIME
+ ccmp w0, #CLOCK_MONOTONIC, #0x4, ne
+ b.ne 1f
+
+ ldr x2, 5f
+ b 2f
+1:
+ cmp w0, #CLOCK_REALTIME_COARSE
+ ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
+ b.ne 4f
+ ldr x2, 6f
+2:
+ stp xzr, x2, [x1]
+
+3: /* res == NULL. */
+ mov w0, wzr
+ ret
+
+4: /* Syscall fallback. */
+ mov x8, #__NR_clock_getres
+ svc #0
+ ret
+5:
+ .quad CLOCK_REALTIME_RES
+6:
+ .quad CLOCK_COARSE_RES
+ .cfi_endproc
+ENDPROC(__kernel_clock_getres)
+
+/*
+ * Read the current time from the architected counter.
+ * Expects vdso_data to be initialised.
+ * Clobbers the temporary registers (x9 - x15).
+ * Returns:
+ * - (x9, x10) = (ts->tv_sec, ts->tv_nsec)
+ * - (x11, x12) = (xtime->tv_sec, xtime->tv_nsec)
+ * - w13 = vDSO sequence counter
+ */
+ENTRY(__do_get_tspec)
+ .cfi_startproc
+
+ /* Read from the vDSO data page. */
+ ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
+ ldp x11, x12, [vdso_data, #VDSO_XTIME_CLK_SEC]
+ ldp w14, w15, [vdso_data, #VDSO_CS_MULT]
+ seqcnt_read w13
+
+ /* Read the physical counter. */
+ isb
+ mrs x9, cntpct_el0
+
+ /* Calculate cycle delta and convert to ns. */
+ sub x10, x9, x10
+ /* We can only guarantee 56 bits of precision. */
+ movn x9, #0xff0, lsl #48
+ and x10, x9, x10
+ mul x10, x10, x14
+ lsr x10, x10, x15
+
+ /* Use the kernel time to calculate the new timespec. */
+ add x10, x12, x10
+ mov x14, #NSEC_PER_SEC_LO16
+ movk x14, #NSEC_PER_SEC_HI16, lsl #16
+ udiv x15, x10, x14
+ add x9, x15, x11
+ mul x14, x14, x15
+ sub x10, x10, x14
+
+ ret
+ .cfi_endproc
+ENDPROC(__do_get_tspec)