arm64: vdso: rework __do_get_tspec register allocation and return shift
In preparation for sub-ns precision in the vdso timespec maths, change the __do_get_tspec register allocation so that we return the clocksource shift value instead of the unused xtime tspec. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon
Catalin Marinas
parent
f84a935db4
commit
d91fb5c267
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@ -62,18 +62,18 @@ ENTRY(__kernel_gettimeofday)
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/* If tv is NULL, skip to the timezone code. */
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cbz x0, 2f
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bl __do_get_tspec
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seqcnt_check w13, 1b
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seqcnt_check w9, 1b
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/* Convert ns to us. */
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mov x11, #1000
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udiv x10, x10, x11
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stp x9, x10, [x0, #TVAL_TV_SEC]
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mov x13, #1000
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udiv x11, x11, x13
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stp x10, x11, [x0, #TVAL_TV_SEC]
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2:
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/* If tz is NULL, return 0. */
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cbz x1, 3f
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ldp w4, w5, [vdso_data, #VDSO_TZ_MINWEST]
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seqcnt_read w13
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seqcnt_check w13, 1b
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seqcnt_read w9
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seqcnt_check w9, 1b
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stp w4, w5, [x1, #TZ_MINWEST]
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3:
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mov x0, xzr
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@ -102,17 +102,17 @@ ENTRY(__kernel_clock_gettime)
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cbnz use_syscall, 7f
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bl __do_get_tspec
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seqcnt_check w13, 1b
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seqcnt_check w9, 1b
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cmp w0, #CLOCK_MONOTONIC
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b.ne 6f
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/* Get wtm timespec. */
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ldp x14, x15, [vdso_data, #VDSO_WTM_CLK_SEC]
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ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC]
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/* Check the sequence counter. */
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seqcnt_read w13
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seqcnt_check w13, 1b
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seqcnt_read w9
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seqcnt_check w9, 1b
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b 4f
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2:
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cmp w0, #CLOCK_REALTIME_COARSE
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@ -122,37 +122,37 @@ ENTRY(__kernel_clock_gettime)
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/* Get coarse timespec. */
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adr vdso_data, _vdso_data
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3: seqcnt_acquire
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ldp x9, x10, [vdso_data, #VDSO_XTIME_CRS_SEC]
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ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
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/* Get wtm timespec. */
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ldp x14, x15, [vdso_data, #VDSO_WTM_CLK_SEC]
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ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC]
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/* Check the sequence counter. */
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seqcnt_read w13
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seqcnt_check w13, 3b
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seqcnt_read w9
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seqcnt_check w9, 3b
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cmp w0, #CLOCK_MONOTONIC_COARSE
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b.ne 6f
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4:
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/* Add on wtm timespec. */
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add x9, x9, x14
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add x10, x10, x15
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add x10, x10, x13
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add x11, x11, x14
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/* Normalise the new timespec. */
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mov x14, #NSEC_PER_SEC_LO16
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movk x14, #NSEC_PER_SEC_HI16, lsl #16
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cmp x10, x14
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mov x15, #NSEC_PER_SEC_LO16
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movk x15, #NSEC_PER_SEC_HI16, lsl #16
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cmp x11, x15
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b.lt 5f
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sub x10, x10, x14
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add x9, x9, #1
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sub x11, x11, x15
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add x10, x10, #1
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5:
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cmp x10, #0
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cmp x11, #0
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b.ge 6f
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add x10, x10, x14
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sub x9, x9, #1
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add x11, x11, x15
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sub x10, x10, #1
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6: /* Store to the user timespec. */
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stp x9, x10, [x1, #TSPEC_TV_SEC]
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stp x10, x11, [x1, #TSPEC_TV_SEC]
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mov x0, xzr
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ret x2
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7:
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@ -203,39 +203,39 @@ ENDPROC(__kernel_clock_getres)
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* Expects vdso_data to be initialised.
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* Clobbers the temporary registers (x9 - x15).
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* Returns:
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* - (x9, x10) = (ts->tv_sec, ts->tv_nsec)
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* - (x11, x12) = (xtime->tv_sec, xtime->tv_nsec)
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* - w13 = vDSO sequence counter
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* - w9 = vDSO sequence counter
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* - (x10, x11) = (ts->tv_sec, ts->tv_nsec)
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* - w12 = cs_shift
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*/
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ENTRY(__do_get_tspec)
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.cfi_startproc
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/* Read from the vDSO data page. */
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ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
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ldp x11, x12, [vdso_data, #VDSO_XTIME_CLK_SEC]
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ldp w14, w15, [vdso_data, #VDSO_CS_MULT]
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seqcnt_read w13
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ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
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ldp w11, w12, [vdso_data, #VDSO_CS_MULT]
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seqcnt_read w9
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/* Read the physical counter. */
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isb
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mrs x9, cntpct_el0
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mrs x15, cntpct_el0
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/* Calculate cycle delta and convert to ns. */
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sub x10, x9, x10
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sub x10, x15, x10
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/* We can only guarantee 56 bits of precision. */
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movn x9, #0xff00, lsl #48
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and x10, x9, x10
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mul x10, x10, x14
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lsr x10, x10, x15
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movn x15, #0xff00, lsl #48
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and x10, x15, x10
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mul x10, x10, x11
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lsr x10, x10, x12
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/* Use the kernel time to calculate the new timespec. */
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add x10, x12, x10
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mov x14, #NSEC_PER_SEC_LO16
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movk x14, #NSEC_PER_SEC_HI16, lsl #16
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udiv x15, x10, x14
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add x9, x15, x11
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mul x14, x14, x15
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sub x10, x10, x14
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mov x11, #NSEC_PER_SEC_LO16
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movk x11, #NSEC_PER_SEC_HI16, lsl #16
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add x15, x10, x14
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udiv x14, x15, x11
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add x10, x13, x14
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mul x13, x14, x11
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sub x11, x15, x13
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ret
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.cfi_endproc
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