https://bugs.kde.org/show_bug.cgi?id=454482
Bug ID: 454482
Summary: valgrind: Unrecognised instruction at address
0x40054a. (assembly code for __NR_getuid32)
Product: valgrind
Version: 3.19.0
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: alfred.pola...@broadcom.com
Target Milestone: ---
SUMMARY
***
When you compile code that executes assembly code to run the function
__NR_getuid32 and run the code through valgrind, valgrind generates a core file
for the process, raises a SIGILL signal and exits ungracefully.
***
STEPS TO REPRODUCE
1. Create a C++ file called usersamp.cpp with the following code:
-------------------------------------
#include <sys/types.h>
#include <sys/syscall.h>
#include <stdio.h>
#ifndef __NR_getuid32
#define __NR_getuid32 199
#endif
#define as_getuid() \
({ int id; asm ("int $128": "=a" (id): "0" (__NR_getuid32)); id; })
int main()
{
int userid = as_getuid();
printf("Getuid definition =%d\n", __NR_getuid32);
printf("This Id: %d\n", userid);
return 0;
}
-------------------------------------
2. Execute the following GNU G++ to compile the code into a Linux debug binary:
g++ -g -o usersamp usersamp.cpp
3. Execute the following Valgrind command to run the Linux debug binary:
valgrind --trace-children=yes --log-file=/tmp/vg_usersamp.out --num-callers=50
--error-limit=no --leak-check=full --show-reachable=yes
--sigill-diagnostics=yes --verbose usersamp
OBSERVED RESULT
Valgrind generates an output saying "Illegal Instruction" then exits
ungracefully. In the attached TAR file, there is a text file called
vg_usersamp.out that has the output file generated by Valgrind and the output
file, in part, has the following information:
----------------------------
vex amd64->IR: unhandled instruction bytes: 0xCD 0x80 0x89 0x45 0xFC 0x8B 0x45
0xFC 0x89 0x45
vex amd64->IR: REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0
vex amd64->IR: VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=NONE
vex amd64->IR: PFX.66=0 PFX.F2=0 PFX.F3=0
==10197== valgrind: Unrecognised instruction at address 0x40054a.
==10197== at 0x40054A: main (usersamp.cpp:11)
==10197== Your program just tried to execute an instruction that Valgrind
==10197== did not recognise. There are two possible reasons for this.
==10197== 1. Your program has a bug and erroneously jumped to a non-code
==10197== location. If you are running Memcheck and you just saw a
==10197== warning about a bad jump, it's probably your program's fault.
==10197== 2. The instruction is legitimate but Valgrind doesn't handle it,
==10197== i.e. it's Valgrind's fault. If you think this is the case or
==10197== you are not sure, please let us know and we'll try to fix it.
==10197== Either way, Valgrind will now raise a SIGILL signal which will
==10197== probably kill your program.
==10197==
==10197== Process terminating with default action of signal 4 (SIGILL): dumping
core
==10197== Illegal opcode at address 0x40054A
==10197== at 0x40054A: main (usersamp.cpp:11)
==10197==
----------------------------
EXPECTED RESULT
Valgrind should have executed the program to completion without exiting
ungracefully.
SOFTWARE/OS VERSIONS
In the attached TAR file, there is a text file called vg_usersamp.out that has
the output file generated by Valgrind and the output file, in part, has the
following information:
----------------------------
--10197-- Contents of /proc/version:
--10197-- Linux version 3.10.0-957.12.2.el7.x86_64
(mockbu...@x86-037.build.eng.bos.redhat.com) (gcc version 4.8.5 20150623 (Red
Hat 4.8.5-36) (GCC) ) #1 SMP Fri Apr 19 21:09:07 UTC 2019
--10197--
--10197-- Arch and hwcaps: AMD64, LittleEndian,
amd64-cx16-lzcnt-rdtscp-sse3-ssse3-avx-avx2-bmi-f16c-rdrand-rdseed
----------------------------
ADDITIONAL INFORMATION
The attached vg_usersamp.tar TAR file contains the following text file:
vg_usersamp.out - The output file generated by Valgrind
vg_usersamp.gdb.core.10197.out - A UNIX script capture of the console output
for a GDB session that examines the core file generated by Valgrind.
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