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https://github.com/golang/go
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runtime: refactor ARM VDSO call setup to helper
We have a very complex process to make VDSO calls on ARM. Create a wrapper helper function which reduces duplication and allows for additional calls from other packages. vdsoCall has a few differences from the original code in walltime/nanotime: * It does not use R0-R3, as they are passed through as arguments to fn. * It does not save g if g.m.gsignal.stack.lo is zero. This may occur if it called at startup on g0 between assigning g0.m.gsignal and setting its stack. For #49182 Change-Id: I51aca514b4835b71142011341d2f09125334d30f Reviewed-on: https://go-review.googlesource.com/c/go/+/362795 Run-TryBot: Michael Pratt <mpratt@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Michael Pratt
parent
c7f870ebc4
commit
876d477b0e
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@ -11,6 +11,8 @@ const (
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_HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30
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)
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func vdsoCall()
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func checkgoarm() {
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// On Android, /proc/self/auxv might be unreadable and hwcap won't
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// reflect the CPU capabilities. Assume that every Android arm device
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@ -262,73 +262,105 @@ TEXT runtime·mincore(SB),NOSPLIT,$0
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MOVW R0, ret+12(FP)
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RET
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TEXT runtime·walltime(SB),NOSPLIT,$8-12
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// Call a VDSO function.
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//
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// R0-R3: arguments to VDSO function (C calling convention)
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// R4: uintptr function to call
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//
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// There is no return value.
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TEXT runtime·vdsoCall(SB),NOSPLIT,$8-0
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// R0-R3 may be arguments to fn, do not touch.
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// R4 is function to call.
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// R5-R9 are available as locals. They are unchanged by the C call
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// (callee-save).
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// We don't know how much stack space the VDSO code will need,
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// so switch to g0.
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// Save old SP. Use R13 instead of SP to avoid linker rewriting the offsets.
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MOVW R13, R4 // R4 is unchanged by C code.
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MOVW R13, R5
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MOVW g_m(g), R5 // R5 is unchanged by C code.
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MOVW g_m(g), R6
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// Set vdsoPC and vdsoSP for SIGPROF traceback.
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// Save the old values on stack and restore them on exit,
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// so this function is reentrant.
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MOVW m_vdsoPC(R5), R1
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MOVW m_vdsoSP(R5), R2
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MOVW R1, 4(R13)
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MOVW R2, 8(R13)
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MOVW m_vdsoPC(R6), R7
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MOVW m_vdsoSP(R6), R8
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MOVW R7, 4(R13)
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MOVW R8, 8(R13)
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MOVW $ret-4(FP), R2 // caller's SP
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MOVW LR, m_vdsoPC(R5)
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MOVW R2, m_vdsoSP(R5)
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MOVW $sp-4(FP), R7 // caller's SP
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MOVW LR, m_vdsoPC(R6)
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MOVW R7, m_vdsoSP(R6)
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MOVW m_curg(R5), R0
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MOVW m_curg(R6), R7
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CMP g, R0 // Only switch if on curg.
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CMP g, R7 // Only switch if on curg.
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B.NE noswitch
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MOVW m_g0(R5), R0
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MOVW (g_sched+gobuf_sp)(R0), R13 // Set SP to g0 stack
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MOVW m_g0(R6), R7
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MOVW (g_sched+gobuf_sp)(R7), R13 // Set SP to g0 stack
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noswitch:
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SUB $24, R13 // Space for results
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BIC $0x7, R13 // Align for C code
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MOVW $CLOCK_REALTIME, R0
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MOVW $8(R13), R1 // timespec
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MOVW runtime·vdsoClockgettimeSym(SB), R2
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CMP $0, R2
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B.EQ fallback
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// Store g on gsignal's stack, so if we receive a signal
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// during VDSO code we can find the g.
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// If we don't have a signal stack, we won't receive signal,
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// so don't bother saving g.
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// When using cgo, we already saved g on TLS, also don't save
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// g here.
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// Also don't save g if we are already on the signal stack.
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// We won't get a nested signal.
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MOVB runtime·iscgo(SB), R6
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CMP $0, R6
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// When using cgo, we already saved g on TLS, also don't save g here.
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MOVB runtime·iscgo(SB), R7
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CMP $0, R7
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BNE nosaveg
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MOVW m_gsignal(R5), R6 // g.m.gsignal
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CMP $0, R6
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// If we don't have a signal stack, we won't receive signal, so don't
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// bother saving g.
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MOVW m_gsignal(R6), R7 // g.m.gsignal
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CMP $0, R7
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BEQ nosaveg
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CMP g, R6
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// Don't save g if we are already on the signal stack, as we won't get
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// a nested signal.
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CMP g, R7
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BEQ nosaveg
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MOVW (g_stack+stack_lo)(R6), R6 // g.m.gsignal.stack.lo
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MOVW g, (R6)
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// If we don't have a signal stack, we won't receive signal, so don't
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// bother saving g.
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MOVW (g_stack+stack_lo)(R7), R7 // g.m.gsignal.stack.lo
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CMP $0, R7
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BEQ nosaveg
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MOVW g, (R7)
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BL (R2)
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BL (R4)
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MOVW $0, R1
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MOVW R1, (R6) // clear g slot, R6 is unchanged by C code
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MOVW $0, R8
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MOVW R8, (R7) // clear g slot
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JMP finish
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nosaveg:
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BL (R2)
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BL (R4)
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finish:
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MOVW R5, R13 // Restore real SP
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// Restore vdsoPC, vdsoSP
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// We don't worry about being signaled between the two stores.
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// If we are not in a signal handler, we'll restore vdsoSP to 0,
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// and no one will care about vdsoPC. If we are in a signal handler,
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// we cannot receive another signal.
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MOVW 8(R13), R7
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MOVW R7, m_vdsoSP(R6)
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MOVW 4(R13), R7
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MOVW R7, m_vdsoPC(R6)
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RET
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TEXT runtime·walltime(SB),NOSPLIT,$12-12
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MOVW $CLOCK_REALTIME, R0
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MOVW $spec-12(SP), R1 // timespec
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MOVW runtime·vdsoClockgettimeSym(SB), R4
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CMP $0, R4
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B.EQ fallback
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BL runtime·vdsoCall(SB)
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JMP finish
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fallback:
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@ -336,19 +368,8 @@ fallback:
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SWI $0
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finish:
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MOVW 8(R13), R0 // sec
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MOVW 12(R13), R2 // nsec
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MOVW R4, R13 // Restore real SP
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// Restore vdsoPC, vdsoSP
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// We don't worry about being signaled between the two stores.
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// If we are not in a signal handler, we'll restore vdsoSP to 0,
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// and no one will care about vdsoPC. If we are in a signal handler,
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// we cannot receive another signal.
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MOVW 8(R13), R1
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MOVW R1, m_vdsoSP(R5)
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MOVW 4(R13), R1
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MOVW R1, m_vdsoPC(R5)
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MOVW sec-12(SP), R0 // sec
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MOVW nsec-8(SP), R2 // nsec
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MOVW R0, sec_lo+0(FP)
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MOVW $0, R1
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@ -356,73 +377,17 @@ finish:
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MOVW R2, nsec+8(FP)
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RET
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// int64 nanotime1(void)
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TEXT runtime·nanotime1(SB),NOSPLIT,$8-8
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// Switch to g0 stack. See comment above in runtime·walltime.
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// Save old SP. Use R13 instead of SP to avoid linker rewriting the offsets.
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MOVW R13, R4 // R4 is unchanged by C code.
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MOVW g_m(g), R5 // R5 is unchanged by C code.
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// Set vdsoPC and vdsoSP for SIGPROF traceback.
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// Save the old values on stack and restore them on exit,
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// so this function is reentrant.
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MOVW m_vdsoPC(R5), R1
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MOVW m_vdsoSP(R5), R2
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MOVW R1, 4(R13)
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MOVW R2, 8(R13)
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MOVW $ret-4(FP), R2 // caller's SP
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MOVW LR, m_vdsoPC(R5)
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MOVW R2, m_vdsoSP(R5)
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MOVW m_curg(R5), R0
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CMP g, R0 // Only switch if on curg.
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B.NE noswitch
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MOVW m_g0(R5), R0
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MOVW (g_sched+gobuf_sp)(R0), R13 // Set SP to g0 stack
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noswitch:
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SUB $24, R13 // Space for results
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BIC $0x7, R13 // Align for C code
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// func nanotime1() int64
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TEXT runtime·nanotime1(SB),NOSPLIT,$12-8
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MOVW $CLOCK_MONOTONIC, R0
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MOVW $8(R13), R1 // timespec
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MOVW runtime·vdsoClockgettimeSym(SB), R2
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CMP $0, R2
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MOVW $spec-12(SP), R1 // timespec
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MOVW runtime·vdsoClockgettimeSym(SB), R4
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CMP $0, R4
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B.EQ fallback
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// Store g on gsignal's stack, so if we receive a signal
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// during VDSO code we can find the g.
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// If we don't have a signal stack, we won't receive signal,
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// so don't bother saving g.
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// When using cgo, we already saved g on TLS, also don't save
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// g here.
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// Also don't save g if we are already on the signal stack.
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// We won't get a nested signal.
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MOVB runtime·iscgo(SB), R6
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CMP $0, R6
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BNE nosaveg
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MOVW m_gsignal(R5), R6 // g.m.gsignal
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CMP $0, R6
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BEQ nosaveg
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CMP g, R6
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BEQ nosaveg
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MOVW (g_stack+stack_lo)(R6), R6 // g.m.gsignal.stack.lo
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MOVW g, (R6)
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BL runtime·vdsoCall(SB)
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BL (R2)
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MOVW $0, R1
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MOVW R1, (R6) // clear g slot, R6 is unchanged by C code
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JMP finish
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nosaveg:
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BL (R2)
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JMP finish
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fallback:
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@ -430,19 +395,8 @@ fallback:
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SWI $0
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finish:
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MOVW 8(R13), R0 // sec
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MOVW 12(R13), R2 // nsec
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MOVW R4, R13 // Restore real SP
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// Restore vdsoPC, vdsoSP
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// We don't worry about being signaled between the two stores.
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// If we are not in a signal handler, we'll restore vdsoSP to 0,
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// and no one will care about vdsoPC. If we are in a signal handler,
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// we cannot receive another signal.
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MOVW 8(R13), R4
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MOVW R4, m_vdsoSP(R5)
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MOVW 4(R13), R4
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MOVW R4, m_vdsoPC(R5)
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MOVW sec-12(SP), R0 // sec
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MOVW nsec-8(SP), R2 // nsec
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MOVW $1000000000, R3
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MULLU R0, R3, (R1, R0)
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@ -451,6 +405,7 @@ finish:
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MOVW R0, ret_lo+0(FP)
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MOVW R1, ret_hi+4(FP)
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RET
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// int32 futex(int32 *uaddr, int32 op, int32 val,
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