diff options
Diffstat (limited to 'arch/arm64/kernel/vdso/gettimeofday.S')
| -rw-r--r-- | arch/arm64/kernel/vdso/gettimeofday.S | 331 |
1 files changed, 206 insertions, 125 deletions
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S index efa79e8d4196..e00b4671bd7c 100644 --- a/arch/arm64/kernel/vdso/gettimeofday.S +++ b/arch/arm64/kernel/vdso/gettimeofday.S @@ -26,24 +26,109 @@ #define NSEC_PER_SEC_HI16 0x3b9a vdso_data .req x6 -use_syscall .req w7 -seqcnt .req w8 +seqcnt .req w7 +w_tmp .req w8 +x_tmp .req x8 + +/* + * Conventions for macro arguments: + * - An argument is write-only if its name starts with "res". + * - All other arguments are read-only, unless otherwise specified. + */ .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 + .macro seqcnt_check fail dmb ishld - ldr \cnt, [vdso_data, #VDSO_TB_SEQ_COUNT] + ldr w_tmp, [vdso_data, #VDSO_TB_SEQ_COUNT] + cmp w_tmp, seqcnt + b.ne \fail .endm - .macro seqcnt_check, cnt, fail - cmp \cnt, seqcnt - b.ne \fail + .macro syscall_check fail + ldr w_tmp, [vdso_data, #VDSO_USE_SYSCALL] + cbnz w_tmp, \fail + .endm + + .macro get_nsec_per_sec res + mov \res, #NSEC_PER_SEC_LO16 + movk \res, #NSEC_PER_SEC_HI16, lsl #16 + .endm + + /* + * Returns the clock delta, in nanoseconds left-shifted by the clock + * shift. + */ + .macro get_clock_shifted_nsec res, cycle_last, mult + /* Read the virtual counter. */ + isb + mrs x_tmp, cntvct_el0 + /* Calculate cycle delta and convert to ns. */ + sub \res, x_tmp, \cycle_last + /* We can only guarantee 56 bits of precision. */ + movn x_tmp, #0xff00, lsl #48 + and \res, x_tmp, \res + mul \res, \res, \mult + .endm + + /* + * Returns in res_{sec,nsec} the REALTIME timespec, based on the + * "wall time" (xtime) and the clock_mono delta. + */ + .macro get_ts_realtime res_sec, res_nsec, \ + clock_nsec, xtime_sec, xtime_nsec, nsec_to_sec + add \res_nsec, \clock_nsec, \xtime_nsec + udiv x_tmp, \res_nsec, \nsec_to_sec + add \res_sec, \xtime_sec, x_tmp + msub \res_nsec, x_tmp, \nsec_to_sec, \res_nsec + .endm + + /* + * Returns in res_{sec,nsec} the timespec based on the clock_raw delta, + * used for CLOCK_MONOTONIC_RAW. + */ + .macro get_ts_clock_raw res_sec, res_nsec, clock_nsec, nsec_to_sec + udiv \res_sec, \clock_nsec, \nsec_to_sec + msub \res_nsec, \res_sec, \nsec_to_sec, \clock_nsec + .endm + + /* sec and nsec are modified in place. */ + .macro add_ts sec, nsec, ts_sec, ts_nsec, nsec_to_sec + /* Add timespec. */ + add \sec, \sec, \ts_sec + add \nsec, \nsec, \ts_nsec + + /* Normalise the new timespec. */ + cmp \nsec, \nsec_to_sec + b.lt 9999f + sub \nsec, \nsec, \nsec_to_sec + add \sec, \sec, #1 +9999: + cmp \nsec, #0 + b.ge 9998f + add \nsec, \nsec, \nsec_to_sec + sub \sec, \sec, #1 +9998: + .endm + + .macro clock_gettime_return, shift=0 + .if \shift == 1 + lsr x11, x11, x12 + .endif + stp x10, x11, [x1, #TSPEC_TV_SEC] + mov x0, xzr + ret + .endm + + .macro jump_slot jumptable, index, label + .if (. - \jumptable) != 4 * (\index) + .error "Jump slot index mismatch" + .endif + b \label .endm .text @@ -51,18 +136,25 @@ seqcnt .req w8 /* 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 w9, 1b + + /* Compute the time of day. */ +1: seqcnt_acquire + syscall_check fail=4f + ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST] + /* w11 = cs_mono_mult, w12 = cs_shift */ + ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT] + ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC] + seqcnt_check fail=1b + + get_nsec_per_sec res=x9 + lsl x9, x9, x12 + + get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11 + get_ts_realtime res_sec=x10, res_nsec=x11, \ + clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9 /* Convert ns to us. */ mov x13, #1000 @@ -76,95 +168,126 @@ ENTRY(__kernel_gettimeofday) stp w4, w5, [x1, #TZ_MINWEST] 3: mov x0, xzr - ret x2 + ret 4: /* Syscall fallback. */ mov x8, #__NR_gettimeofday svc #0 - ret x2 + ret .cfi_endproc ENDPROC(__kernel_gettimeofday) +#define JUMPSLOT_MAX CLOCK_MONOTONIC_COARSE + /* 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 + cmp w0, #JUMPSLOT_MAX + b.hi syscall + adr vdso_data, _vdso_data + adr x_tmp, jumptable + add x_tmp, x_tmp, w0, uxtw #2 + br x_tmp + + ALIGN +jumptable: + jump_slot jumptable, CLOCK_REALTIME, realtime + jump_slot jumptable, CLOCK_MONOTONIC, monotonic + b syscall + b syscall + jump_slot jumptable, CLOCK_MONOTONIC_RAW, monotonic_raw + jump_slot jumptable, CLOCK_REALTIME_COARSE, realtime_coarse + jump_slot jumptable, CLOCK_MONOTONIC_COARSE, monotonic_coarse + + .if (. - jumptable) != 4 * (JUMPSLOT_MAX + 1) + .error "Wrong jumptable size" + .endif + + ALIGN +realtime: + seqcnt_acquire + syscall_check fail=syscall + ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST] + /* w11 = cs_mono_mult, w12 = cs_shift */ + ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT] + ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC] + seqcnt_check fail=realtime - mov x2, x30 - .cfi_register x30, x2 + /* All computations are done with left-shifted nsecs. */ + get_nsec_per_sec res=x9 + lsl x9, x9, x12 - /* Get kernel timespec. */ - adr vdso_data, _vdso_data -1: seqcnt_acquire - cbnz use_syscall, 7f + get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11 + get_ts_realtime res_sec=x10, res_nsec=x11, \ + clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9 + clock_gettime_return, shift=1 - bl __do_get_tspec - seqcnt_check w9, 1b + ALIGN +monotonic: + seqcnt_acquire + syscall_check fail=syscall + ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST] + /* w11 = cs_mono_mult, w12 = cs_shift */ + ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT] + ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC] + ldp x3, x4, [vdso_data, #VDSO_WTM_CLK_SEC] + seqcnt_check fail=monotonic - mov x30, x2 + /* All computations are done with left-shifted nsecs. */ + lsl x4, x4, x12 + get_nsec_per_sec res=x9 + lsl x9, x9, x12 - cmp w0, #CLOCK_MONOTONIC - b.ne 6f + get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11 + get_ts_realtime res_sec=x10, res_nsec=x11, \ + clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9 - /* Get wtm timespec. */ - ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC] + add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9 + clock_gettime_return, shift=1 - /* Check the sequence counter. */ - seqcnt_read w9 - seqcnt_check w9, 1b - b 4f -2: - cmp w0, #CLOCK_REALTIME_COARSE - ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne - b.ne 8f + ALIGN +monotonic_raw: + seqcnt_acquire + syscall_check fail=syscall + ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST] + /* w11 = cs_raw_mult, w12 = cs_shift */ + ldp w12, w11, [vdso_data, #VDSO_CS_SHIFT] + ldp x13, x14, [vdso_data, #VDSO_RAW_TIME_SEC] + seqcnt_check fail=monotonic_raw - /* xtime_coarse_nsec is already right-shifted */ - mov x12, #0 + /* All computations are done with left-shifted nsecs. */ + lsl x14, x14, x12 + get_nsec_per_sec res=x9 + lsl x9, x9, x12 - /* Get coarse timespec. */ - adr vdso_data, _vdso_data -3: seqcnt_acquire + get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11 + get_ts_clock_raw res_sec=x10, res_nsec=x11, \ + clock_nsec=x15, nsec_to_sec=x9 + + add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9 + clock_gettime_return, shift=1 + + ALIGN +realtime_coarse: + seqcnt_acquire ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC] + seqcnt_check fail=realtime_coarse + clock_gettime_return - /* Get wtm timespec. */ + ALIGN +monotonic_coarse: + seqcnt_acquire + ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC] ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC] + seqcnt_check fail=monotonic_coarse - /* Check the sequence counter. */ - seqcnt_read w9 - seqcnt_check w9, 3b + /* Computations are done in (non-shifted) nsecs. */ + get_nsec_per_sec res=x9 + add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9 + clock_gettime_return - cmp w0, #CLOCK_MONOTONIC_COARSE - b.ne 6f -4: - /* Add on wtm timespec. */ - add x10, x10, x13 - lsl x14, x14, x12 - add x11, x11, x14 - - /* Normalise the new timespec. */ - mov x15, #NSEC_PER_SEC_LO16 - movk x15, #NSEC_PER_SEC_HI16, lsl #16 - lsl x15, x15, x12 - cmp x11, x15 - b.lt 5f - sub x11, x11, x15 - add x10, x10, #1 -5: - cmp x11, #0 - b.ge 6f - add x11, x11, x15 - sub x10, x10, #1 - -6: /* Store to the user timespec. */ - lsr x11, x11, x12 - stp x10, x11, [x1, #TSPEC_TV_SEC] - mov x0, xzr - ret -7: - mov x30, x2 -8: /* Syscall fallback. */ + ALIGN +syscall: /* Syscall fallback. */ mov x8, #__NR_clock_gettime svc #0 ret @@ -176,6 +299,7 @@ ENTRY(__kernel_clock_getres) .cfi_startproc cmp w0, #CLOCK_REALTIME ccmp w0, #CLOCK_MONOTONIC, #0x4, ne + ccmp w0, #CLOCK_MONOTONIC_RAW, #0x4, ne b.ne 1f ldr x2, 5f @@ -203,46 +327,3 @@ ENTRY(__kernel_clock_getres) .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: - * - w9 = vDSO sequence counter - * - (x10, x11) = (ts->tv_sec, shifted ts->tv_nsec) - * - w12 = cs_shift - */ -ENTRY(__do_get_tspec) - .cfi_startproc - - /* Read from the vDSO data page. */ - ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST] - ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC] - ldp w11, w12, [vdso_data, #VDSO_CS_MULT] - seqcnt_read w9 - - /* Read the virtual counter. */ - isb - mrs x15, cntvct_el0 - - /* Calculate cycle delta and convert to ns. */ - sub x10, x15, x10 - /* We can only guarantee 56 bits of precision. */ - movn x15, #0xff00, lsl #48 - and x10, x15, x10 - mul x10, x10, x11 - - /* Use the kernel time to calculate the new timespec. */ - mov x11, #NSEC_PER_SEC_LO16 - movk x11, #NSEC_PER_SEC_HI16, lsl #16 - lsl x11, x11, x12 - add x15, x10, x14 - udiv x14, x15, x11 - add x10, x13, x14 - mul x13, x14, x11 - sub x11, x15, x13 - - ret - .cfi_endproc -ENDPROC(__do_get_tspec) |