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benshi001 opened this issue Jun 23, 2017 · 9 comments
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x/arch/arm/armasm: MSR instruction is not supported #20762

benshi001 opened this issue Jun 23, 2017 · 9 comments
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@benshi001
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benshi001 commented Jun 23, 2017 •
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decode_test.go:66: Decode(01f02ce1|) [plan9] = error: unknown instruction, 0, want MSR R1, CPSR
decode_test.go:66: Decode(fff02ce3|) [plan9] = error: unknown instruction, 0, want MSR $255, CPSR
decode_test.go:66: Decode(fff42ce3|) [plan9] = error: unknown instruction, 0, want MSR $4278190080, CPSR

All those are common ARM instructions, which should be correctly decoded.
@odeke-em
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odeke-em commented Jun 23, 2017 •
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@benshi001 what package is this issue for? Is it for x/arch/arm/armasm or for cmd/internal/objfile? Could we update the title to something that can easily be groked?
Thanks.

/cc @cherrymui @randall77 @josharian

@benshi001 benshi001 changed the title defects of the disassembler defects of arm's disassembler Jun 23, 2017
@benshi001 benshi001 changed the title defects of arm's disassembler https://go.googlesource.com/arch/+/master/arm/armasm/: defects of arm's disassembler Jun 23, 2017
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benshi001 commented Jun 23, 2017 •
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01f02ce1|	1	plan9	MSR R1, CPSR
fff02ce3|	1	plan9	MSR $255, CPSR
fff42ce3|	1	plan9	MSR $4278190080, CPSR

add to arm/armasm/testdata/decode.txt

@odeke-em odeke-em changed the title https://go.googlesource.com/arch/+/master/arm/armasm/: defects of arm's disassembler x/arch/arm/armasm: incorrect disassembly of some instructions on plan9 Jun 23, 2017
@benshi001
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benshi001 commented Jun 23, 2017 •
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here is gnu objdump's result

10: e12cf001 msr CPSR_fs, r1
14: e32cfff0 msr CPSR_fs, # 240, 30 ; 0x3c0
18: e32cfff4 msr CPSR_fs, # 244, 30 ; 0x3d0

@bradfitz bradfitz added this to the Go1.10 milestone Jun 23, 2017
@bradfitz bradfitz added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Jun 23, 2017
@cherrymui
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@odeke-em it is x/arch/arm/armasm.

All those are common ARM instructions

They are rarely used in Go. Given that it doesn't disassemble to some other instruction, I would say it is "unsupported" yet, instead of "incorrect".

Does it work in GNU syntax? (I mean, GNU syntax in x/arch/arm/armasm, not GNU objudump).

@cherrymui cherrymui modified the milestones: Unreleased, Go1.10 Jun 23, 2017
@cherrymui cherrymui changed the title x/arch/arm/armasm: incorrect disassembly of some instructions on plan9 x/arch/arm/armasm: MSR instruction is not supported Jun 23, 2017
@benshi001
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No. it is not supported in GNU syntax x/arch/arm/armasm

@benshi001
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The register list order is wrong when decoding QADD/QDADD/QSUB.

0xe1086055 should be decoded to "QADD R6, R8, R5" in GNU syntax, but actually "QADD R6, R5, R8". So do QDADD and QSUB.

@benshi001
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Sorry, I made a mistake again. The QADD/QSUB/QDSUB/QDADD are right in register order. Theirs are indeed different from QADD16/QSUB16/QADD8/QSUB8.

@gopherbot
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CL https://golang.org/cl/48310 mentions this issue.

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Change https://golang.org/cl/49530 mentions this issue: cmd/vendor/golang.org/x/arch: pull updates from x repo

gopherbot pushed a commit that referenced this issue Aug 16, 2017
@cherrymui
cmd/vendor/golang.org/x/arch: pull updates from x repo
56b62c7 
Vendor from golang.org/x/arch (commit f185940).

Implements #19157

Updates #12840
Updates #20762
Updates #20897
Updates #20096
Updates #20766
Updates #20752
Updates #20096
Updates #19142

Change-Id: Idefb8ba2c355dc07f3b9e8dcf5f00173256a0f0f
Reviewed-on: https://go-review.googlesource.com/49530
Reviewed-by: Cherry Zhang <[email protected]>
@golang golang locked and limited conversation to collaborators Jul 27, 2018
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