diff options
Diffstat (limited to 'src/runtime/asm_arm64.s')
| -rw-r--r-- | src/runtime/asm_arm64.s | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s index 9ef7346e00..956910f6ce 100644 --- a/src/runtime/asm_arm64.s +++ b/src/runtime/asm_arm64.s @@ -96,6 +96,10 @@ nocgo: // start this M BL runtime·mstart(SB) + // Prevent dead-code elimination of debugCallV2, which is + // intended to be called by debuggers. + MOVD $runtime·debugCallV2<ABIInternal>(SB), R0 + MOVD $0, R0 MOVD R0, (R0) // boom UNDEF @@ -1240,6 +1244,200 @@ flush: LDP 21*8(RSP), (R25, R26) JMP ret +DATA debugCallFrameTooLarge<>+0x00(SB)/20, $"call frame too large" +GLOBL debugCallFrameTooLarge<>(SB), RODATA, $20 // Size duplicated below + +// debugCallV2 is the entry point for debugger-injected function +// calls on running goroutines. It informs the runtime that a +// debug call has been injected and creates a call frame for the +// debugger to fill in. +// +// To inject a function call, a debugger should: +// 1. Check that the goroutine is in state _Grunning and that +// there are at least 288 bytes free on the stack. +// 2. Set SP as SP-16. +// 3. Store the current LR in (SP) (using the SP after step 2). +// 4. Store the current PC in the LR register. +// 5. Write the desired argument frame size at SP-16 +// 6. Save all machine registers (including flags and fpsimd reigsters) +// so they can be restored later by the debugger. +// 7. Set the PC to debugCallV2 and resume execution. +// +// If the goroutine is in state _Grunnable, then it's not generally +// safe to inject a call because it may return out via other runtime +// operations. Instead, the debugger should unwind the stack to find +// the return to non-runtime code, add a temporary breakpoint there, +// and inject the call once that breakpoint is hit. +// +// If the goroutine is in any other state, it's not safe to inject a call. +// +// This function communicates back to the debugger by setting R20 and +// invoking BRK to raise a breakpoint signal. See the comments in the +// implementation for the protocol the debugger is expected to +// follow. InjectDebugCall in the runtime tests demonstrates this protocol. +// +// The debugger must ensure that any pointers passed to the function +// obey escape analysis requirements. Specifically, it must not pass +// a stack pointer to an escaping argument. debugCallV2 cannot check +// this invariant. +// +// This is ABIInternal because Go code injects its PC directly into new +// goroutine stacks. +TEXT runtime·debugCallV2<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0 + STP (R29, R30), -280(RSP) + SUB $272, RSP, RSP + SUB $8, RSP, R29 + // Save all registers that may contain pointers so they can be + // conservatively scanned. + // + // We can't do anything that might clobber any of these + // registers before this. + STP (R27, g), (30*8)(RSP) + STP (R25, R26), (28*8)(RSP) + STP (R23, R24), (26*8)(RSP) + STP (R21, R22), (24*8)(RSP) + STP (R19, R20), (22*8)(RSP) + STP (R16, R17), (20*8)(RSP) + STP (R14, R15), (18*8)(RSP) + STP (R12, R13), (16*8)(RSP) + STP (R10, R11), (14*8)(RSP) + STP (R8, R9), (12*8)(RSP) + STP (R6, R7), (10*8)(RSP) + STP (R4, R5), (8*8)(RSP) + STP (R2, R3), (6*8)(RSP) + STP (R0, R1), (4*8)(RSP) + + // Perform a safe-point check. + MOVD R30, 8(RSP) // Caller's PC + CALL runtime·debugCallCheck(SB) + MOVD 16(RSP), R0 + CBZ R0, good + + // The safety check failed. Put the reason string at the top + // of the stack. + MOVD R0, 8(RSP) + MOVD 24(RSP), R0 + MOVD R0, 16(RSP) + + // Set R20 to 8 and invoke BRK. The debugger should get the + // reason a call can't be injected from SP+8 and resume execution. + MOVD $8, R20 + BRK + JMP restore + +good: + // Registers are saved and it's safe to make a call. + // Open up a call frame, moving the stack if necessary. + // + // Once the frame is allocated, this will set R20 to 0 and + // invoke BRK. The debugger should write the argument + // frame for the call at SP+8, set up argument registers, + // set the lr as the signal PC + 4, set the PC to the function + // to call, set R26 to point to the closure (if a closure call), + // and resume execution. + // + // If the function returns, this will set R20 to 1 and invoke + // BRK. The debugger can then inspect any return value saved + // on the stack at SP+8 and in registers and resume execution again. + // + // If the function panics, this will set R20 to 2 and invoke BRK. + // The interface{} value of the panic will be at SP+8. The debugger + // can inspect the panic value and resume execution again. +#define DEBUG_CALL_DISPATCH(NAME,MAXSIZE) \ + CMP $MAXSIZE, R0; \ + BGT 5(PC); \ + MOVD $NAME(SB), R0; \ + MOVD R0, 8(RSP); \ + CALL runtime·debugCallWrap(SB); \ + JMP restore + + MOVD 256(RSP), R0 // the argument frame size + DEBUG_CALL_DISPATCH(debugCall32<>, 32) + DEBUG_CALL_DISPATCH(debugCall64<>, 64) + DEBUG_CALL_DISPATCH(debugCall128<>, 128) + DEBUG_CALL_DISPATCH(debugCall256<>, 256) + DEBUG_CALL_DISPATCH(debugCall512<>, 512) + DEBUG_CALL_DISPATCH(debugCall1024<>, 1024) + DEBUG_CALL_DISPATCH(debugCall2048<>, 2048) + DEBUG_CALL_DISPATCH(debugCall4096<>, 4096) + DEBUG_CALL_DISPATCH(debugCall8192<>, 8192) + DEBUG_CALL_DISPATCH(debugCall16384<>, 16384) + DEBUG_CALL_DISPATCH(debugCall32768<>, 32768) + DEBUG_CALL_DISPATCH(debugCall65536<>, 65536) + // The frame size is too large. Report the error. + MOVD $debugCallFrameTooLarge<>(SB), R0 + MOVD R0, 8(RSP) + MOVD $20, R0 + MOVD R0, 16(RSP) // length of debugCallFrameTooLarge string + MOVD $8, R20 + BRK + JMP restore + +restore: + // Calls and failures resume here. + // + // Set R20 to 16 and invoke BRK. The debugger should restore + // all registers except for PC and RSP and resume execution. + MOVD $16, R20 + BRK + // We must not modify flags after this point. + + // Restore pointer-containing registers, which may have been + // modified from the debugger's copy by stack copying. + LDP (30*8)(RSP), (R27, g) + LDP (28*8)(RSP), (R25, R26) + LDP (26*8)(RSP), (R23, R24) + LDP (24*8)(RSP), (R21, R22) + LDP (22*8)(RSP), (R19, R20) + LDP (20*8)(RSP), (R16, R17) + LDP (18*8)(RSP), (R14, R15) + LDP (16*8)(RSP), (R12, R13) + LDP (14*8)(RSP), (R10, R11) + LDP (12*8)(RSP), (R8, R9) + LDP (10*8)(RSP), (R6, R7) + LDP (8*8)(RSP), (R4, R5) + LDP (6*8)(RSP), (R2, R3) + LDP (4*8)(RSP), (R0, R1) + + LDP -8(RSP), (R29, R27) + ADD $288, RSP, RSP // Add 16 more bytes, see saveSigContext + MOVD -16(RSP), R30 // restore old lr + JMP (R27) + +// runtime.debugCallCheck assumes that functions defined with the +// DEBUG_CALL_FN macro are safe points to inject calls. +#define DEBUG_CALL_FN(NAME,MAXSIZE) \ +TEXT NAME(SB),WRAPPER,$MAXSIZE-0; \ + NO_LOCAL_POINTERS; \ + MOVD $0, R20; \ + BRK; \ + MOVD $1, R20; \ + BRK; \ + RET +DEBUG_CALL_FN(debugCall32<>, 32) +DEBUG_CALL_FN(debugCall64<>, 64) +DEBUG_CALL_FN(debugCall128<>, 128) +DEBUG_CALL_FN(debugCall256<>, 256) +DEBUG_CALL_FN(debugCall512<>, 512) +DEBUG_CALL_FN(debugCall1024<>, 1024) +DEBUG_CALL_FN(debugCall2048<>, 2048) +DEBUG_CALL_FN(debugCall4096<>, 4096) +DEBUG_CALL_FN(debugCall8192<>, 8192) +DEBUG_CALL_FN(debugCall16384<>, 16384) +DEBUG_CALL_FN(debugCall32768<>, 32768) +DEBUG_CALL_FN(debugCall65536<>, 65536) + +// func debugCallPanicked(val interface{}) +TEXT runtime·debugCallPanicked(SB),NOSPLIT,$16-16 + // Copy the panic value to the top of stack at SP+8. + MOVD val_type+0(FP), R0 + MOVD R0, 8(RSP) + MOVD val_data+8(FP), R0 + MOVD R0, 16(RSP) + MOVD $2, R20 + BRK + RET + // Note: these functions use a special calling convention to save generated code space. // Arguments are passed in registers, but the space for those arguments are allocated // in the caller's stack frame. These stubs write the args into that stack space and |