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| author | Austin Clements <austin@google.com> | 2021-04-13 08:44:56 -0400 |
|---|---|---|
| committer | Austin Clements <austin@google.com> | 2021-04-13 21:13:12 +0000 |
| commit | c19759aa487f7d6f479daa00e7462425f4efc481 (patch) | |
| tree | a580e1b01eeb2ecdb81d383e922ad8bb155095b5 /src/runtime/sys_windows_arm64.s | |
| parent | e69f02265c74529a368a2ff27fdce4aeb3483e8b (diff) | |
| download | go-c19759aa487f7d6f479daa00e7462425f4efc481.tar.xz | |
runtime: eliminate externalthreadhandler
This function is no longer used.
Eliminating this actually fixes several problems:
- It made assumptions about what registers memclrNoHeapPointers would
preserve. Besides being an abstraction violation and lurking
maintenance issue, this actively became a problem for regabi because
the call to memclrNoHeapPointers now happens through an ABI wrapper,
which is generated by the compiler and hence we can't easily control
what registers it clobbers.
- The amd64 implementation (at least), does not interact with the host
ABI correctly. Notably, it doesn't save many of the registers that
are callee-save in the host ABI but caller-save in the Go ABI.
- It interacts strangely with the NOSPLIT checker because it allocates
an entire M and G on its stack. It worked around this on arm64, and
happened to do things the NOSPLIT checker couldn't track on 386 and
amd64, and happened to be *4 bytes* below the limit on arm (so any
addition to the m or g structs would cause a NOSPLIT failure). See
CL 309031 for a more complete explanation.
Fixes #45530.
Updates #40724.
Change-Id: Ic70d4d7e1c17f1d796575b3377b8529449e93576
Reviewed-on: https://go-review.googlesource.com/c/go/+/309634
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Diffstat (limited to 'src/runtime/sys_windows_arm64.s')
| -rw-r--r-- | src/runtime/sys_windows_arm64.s | 60 |
1 files changed, 0 insertions, 60 deletions
diff --git a/src/runtime/sys_windows_arm64.s b/src/runtime/sys_windows_arm64.s index 70f628c27d..6b28a0c2ef 100644 --- a/src/runtime/sys_windows_arm64.s +++ b/src/runtime/sys_windows_arm64.s @@ -299,66 +299,6 @@ TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0 MOVD $runtime·lastcontinuehandler<ABIInternal>(SB), R1 B sigtramp<>(SB) -// externalthreadhander called with R0 = uint32 arg, R1 = Go function f. -// Need to call f(arg), which returns a uint32, and return it in R0. -TEXT runtime·externalthreadhandler<ABIInternal>(SB),NOSPLIT|TOPFRAME,$96-0 - NO_LOCAL_POINTERS - - // Push C callee-save registers R19-R28. LR, FP already saved. - SAVE_R19_TO_R28(-10*8) - - // Allocate space for args, saved R0+R1, g, and m structures. - // Hide from nosplit check. - #define extra ((64+g__size+m__size+15)&~15) - SUB $extra, RSP, R2 // hide from nosplit overflow check - MOVD R2, RSP - - // Save R0 and R1 (our args). - MOVD R0, 32(RSP) - MOVD R1, 40(RSP) - - // Zero out m and g structures. - MOVD $64(RSP), R0 - MOVD R0, 8(RSP) - MOVD $(m__size + g__size), R0 - MOVD R0, 16(RSP) - MOVD $0, 0(RSP) // not-saved LR - BL runtime·memclrNoHeapPointers(SB) - - // Initialize m and g structures. - MOVD $64(RSP), g - MOVD $g__size(g), R3 // m - MOVD R3, g_m(g) // g->m = m - MOVD g, m_g0(R3) // m->g0 = g - MOVD g, m_curg(R3) // m->curg = g - MOVD RSP, R0 - MOVD R0, g_stack+stack_hi(g) - SUB $(32*1024), R0 - MOVD R0, (g_stack+stack_lo)(g) - MOVD R0, g_stackguard0(g) - MOVD R0, g_stackguard1(g) - BL runtime·save_g(SB) - - // Call function. - MOVD 32(RSP), R0 - MOVD 40(RSP), R1 - MOVW R0, 8(RSP) - BL (R1) - - // Clear g. - MOVD $0, g - BL runtime·save_g(SB) - - // Load return value (save_g would have smashed) - MOVW (2*8)(RSP), R0 - - ADD $extra, RSP, R2 - MOVD R2, RSP - #undef extra - - RESTORE_R19_TO_R28(-10*8) - RET - GLOBL runtime·cbctxts(SB), NOPTR, $4 TEXT runtime·callbackasm1<ABIInternal>(SB),NOSPLIT,$208-0 |