Bug 172034
| Summary: | bad disassembly for 0xC7 /1 "movl $___," | ||||||
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| Product: | [Fedora] Fedora | Reporter: | John Reiser <jreiser> | ||||
| Component: | gdb | Assignee: | Jan Kratochvil <jan.kratochvil> | ||||
| Status: | CLOSED CURRENTRELEASE | QA Contact: | |||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | 5 | CC: | cagney, jan.kratochvil | ||||
| Target Milestone: | --- | ||||||
| Target Release: | --- | ||||||
| Hardware: | i386 | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | gdb-6.5-15.fc6 | Doc Type: | Bug Fix | ||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2007-01-26 23:11:48 UTC | Type: | --- | ||||
| Regression: | --- | Mount Type: | --- | ||||
| Documentation: | --- | CRM: | |||||
| Verified Versions: | Category: | --- | |||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||
| Embargoed: | |||||||
| Bug Depends On: | |||||||
| Bug Blocks: | 208476, 210786 | ||||||
| Attachments: |
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Created attachment 131292 [details] libopcodes CVS version patch See IA-32 Intel® Architecture Software Developer's Manual Volume 2B: Instruction Set Reference, N-Z, page 434 (of 582), http://download.intel.com/design/Pentium4/manuals/25366719.pdf Opcodes 0xC6 and 0xC7 do not have ('reg' (Bits 5,4,3) != 0) defined. H. J. Lu committed modified patch to CVS upstream. To be fixed in gdb-6.5-11.fc6, thanks for your bugreport. gdb-6.5-13.fc6 has been pushed for fc6, which should resolve this issue. If these problems are still present in this version, then please make note of it in this bug report. This report targets the FC3 or FC4 products, which have now been EOL'd. Could you please check that it still applies to a current Fedora release, and either update the target product or close it ? Thanks. The bug persists in gdb-6.3.0.0-1.134.fc5. The bug has been fixed in gdb-6.5-15.fc6. I changed the Version in this bugzilla report to 'fc5'. While thanks for the bugreport and also the recent verification I have to say the FC5 backport of this bug and FC5 gdb update will not happen. FC5 is going soon into the Fedora Legacy mode. Please upgrade to FC6 or FC7test1. |
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20050922 Fedora/1.0.7-1.1.fc4 Firefox/1.0.7 Description of problem: On x86, the byte sequence {0xc7,0310,1,2,3,4} superficially looks like "move immediate to r/m dword" because of the opcode 0xC7. Actually, it is an illegal instruction because 0!=(070 & mod_rm); namely, the 0310 should be 0300. Gdb disassembly should report illegal instruction, but instead says "movl $0x4030201,%eax". Version-Release number of selected component (if applicable): gdb-6.3.0.0-1.21 How reproducible: Always Steps to Reproduce: 1. Compile and run this program under gdb: -----foo.S _start: .globl _start nop; int3 .byte 0xc7,0310,1,2,3,4 nop; nop ----- $ gcc -o foo -nostartfiles -nostdlib foo.S $ gdb foo (gdb) run 2. 3. Actual Results: Program received signal SIGTRAP, Trace/breakpoint trap. ## as expected for 'int3' 0x08048076 in _start () (gdb) x/i $pc 0x8048076 <_start+2>: mov $0x4030201,%eax ## gdb says it's OK (gdb) stepi Program received signal SIGILL, Illegal instruction. ## CPU rejects 0x08048076 in _start () 0x8048076 <_start+2>: mov $0x4030201,%eax (gdb) Expected Results: Program received signal SIGTRAP, Trace/breakpoint trap. 0x08048076 in _start () (gdb) x/i $pc 0x8048076 <_start+2>: (bad) ## modrm of 0310 is illegal for opcode 0xC7 Additional info: