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cmd/internal/disasm: RISCV64C disassembly support #71102

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Jorropo opened this issue Jan 3, 2025 · 4 comments
Open

cmd/internal/disasm: RISCV64C disassembly support #71102

Jorropo opened this issue Jan 3, 2025 · 4 comments
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arch-riscv Issues solely affecting the riscv64 architecture. FixPending Issues that have a fix which has not yet been reviewed or submitted. NeedsFix The path to resolution is known, but the work has not been done.
Milestone
Go1.25

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@Jorropo
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Jorropo commented Jan 3, 2025

I am working on #47560 https://go-review.googlesource.com/c/go/+/639656/1 and I notice that go tool objdump seems to not be able to disassemble my instructions properly.

First function of a random binary:

--- /tmp/old	2025-01-03 06:36:17.640800526 +0100
+++ /tmp/new	2025-01-03 06:36:26.500944550 +0100
@@ -2,20 +2,20 @@
   type.go:140           0x11000                 010db303                MOV 16(X27), X6                                 
   type.go:140           0x11004                 00236a63                BLTU X6, X2, 5(PC)                              
   type.go:140           0x11008                 00a10423                MOVB X10, 8(X2)                                 
-  type.go:140           0x1100c                 1b45d2ef                JAL X5, runtime.morestack_noctxt.abi0(SB)       
+  type.go:140           0x1100c                 17c592ef                JAL X5, runtime.morestack_noctxt.abi0(SB)       
   type.go:140           0x11010                 00814503                MOVBU 8(X2), X10                                
   type.go:140           0x11014                 fedff06f                JMP internal/abi.Kind.String(SB)                
   type.go:140           0x11018                 fe113423                MOV X1, -24(X2)                                 
   type.go:140           0x1101c                 fe810113                ADDI $-24, X2, X2                               
   type.go:140           0x11020                 00113023                MOV X1, (X2)                                    
-  type.go:141           0x11024                 000f0397                AUIPC $240, X7                                  
+  type.go:141           0x11024                 000e0397                AUIPC $224, X7                                  
   type.go:141           0x11028                 dfc3b383                MOV -516(X7), X7                                
   type.go:141           0x1102c                 0ff57413                MOVBU X10, X8                                   
-  type.go:141           0x11030                 000f0497                AUIPC $240, X9                                  
+  type.go:141           0x11030                 000e0497                AUIPC $224, X9                                  
   type.go:141           0x11034                 df84b483                MOV -520(X9), X9                                
   type.go:141           0x11038                 02944063                BLT X8, X9, 8(PC)                               
   type.go:144           0x1103c                 00000293                MOV X0, X5                                      
-  type.go:144           0x11040                 0292fc63                BGEU X5, X9, 14(PC)                             
+  type.go:144           0x11040                 0292fb63                BGEU X5, X9, 13(PC)                             
   type.go:144           0x11044                 0003b503                MOV (X7), X10                                   
   type.go:144           0x11048                 0083b583                MOV 8(X7), X11                                  
   type.go:144           0x1104c                 00013083                MOV (X2), X1                                    
@@ -23,12 +23,11 @@
   type.go:144           0x11054                 00008067                RET                                             
   type.go:142           0x11058                 03851293                SLLI $56, X10, X5                               
   type.go:142           0x1105c                 0342d293                SRLI $52, X5, X5                                
-  type.go:142           0x11060                 005382b3                ADD X5, X7, X5      
+  type.go:142           0x11060                 b503929e                ADD X7, X5, X5                             
-  type.go:142           0x11064                 0002b503                MOV (X5), X10                                   
-  type.go:142           0x11068                 0082b583                MOV 8(X5), X11                                  
-  type.go:142           0x1106c                 00013083                MOV (X2), X1                                    
-  type.go:142           0x11070                 01810113                ADDI $24, X2, X2                                
-  type.go:142           0x11074                 00008067                RET                                             
-  type.go:144           0x11078                 00028313                MOV X5, X6                                      
-  type.go:144           0x1107c                 34c5d0ef                CALL runtime.panicIndex(SB)                     
-  type.go:144           0x11080                 00000013                MOV X0, X0                                 
+  type.go:142           0x1106c                 01130001                MOV X0, X0                                      
+  type.go:142           0x11064                 b5830002                ?                                               
+  type.go:142           0x11068                 30830082                ?                                               
+  type.go:142           0x1106c                 01130001                MOV X0, X0                                      
+  type.go:142           0x11070                 80670181                ?                                               
+  type.go:142           0x11074                 83160000                UNIMP                                           
+  type.go:144           0x11078                 308590ef                CALL runtime.panicIndex(SB)                     
+  type.go:144           0x1107c                 00000001                MOV X0, X0
@Jorropo Jorropo changed the title x/arch: RISCV64C support x/arch: RISCV64C disassembly support Jan 3, 2025
@gopherbot
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Change https://go.dev/cl/639995 mentions this issue: cmd/internal/disasm: correct instruction length handling for riscv64

@4a6f656c
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4a6f656c commented Jan 3, 2025

This is most likely due to a bug in cmd/internal/disasm - could you try https://go-review.googlesource.com/c/go/+/639995 ?

@Jorropo Jorropo changed the title x/arch: RISCV64C disassembly support cmd/disasm: RISCV64C disassembly support Jan 3, 2025
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Jorropo commented Jan 3, 2025

indeed thx

@dmitshur dmitshur added this to the Go1.25 milestone Jan 3, 2025
@dmitshur dmitshur added NeedsFix The path to resolution is known, but the work has not been done. FixPending Issues that have a fix which has not yet been reviewed or submitted. labels Jan 3, 2025
@dmitshur dmitshur changed the title cmd/disasm: RISCV64C disassembly support cmd/internal/disasm: RISCV64C disassembly support Jan 3, 2025
@dmitshur dmitshur added the arch-riscv Issues solely affecting the riscv64 architecture. label Jan 3, 2025
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4a6f656c commented Jan 4, 2025

It would be worth including this fix in Go 1.24 since this code was only added this cycle.

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arch-riscv Issues solely affecting the riscv64 architecture. FixPending Issues that have a fix which has not yet been reviewed or submitted. NeedsFix The path to resolution is known, but the work has not been done.
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