[Qemu-devel] [REGRESSION] mprotect in guest makes qemu-i386 crash

[Qemu-devel] [REGRESSION] mprotect in guest makes qemu-i386 crash

[Jan Kiszka]

Hi,

this fragment from a code self-modification test of mine used to work a
few weeks ago with qemu-i386 userspace emulation. Now it causes a segfault.

#include <sys/mman.h>
main()
{
	mprotect((void *)((unsigned long)main & ~0xfff), 0x1000,
		 PROT_READ|PROT_WRITE|PROT_EXEC);
}

qemu-x86_64 even complains about an "Unsupported syscall: 221", while
the same 64-bit binary works fine with 0.9.1 (I don't recall anymore if
it worked recently with SVN head).

Anyone some idea? Known issue?

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

[Qemu-devel] Re: [REGRESSION] mprotect in guest makes qemu-i386 crash

[Jan Kiszka]

Jan Kiszka wrote:
> Hi,
> 
> this fragment from a code self-modification test of mine used to work a
> few weeks ago with qemu-i386 userspace emulation. Now it causes a segfault.
> 
> #include <sys/mman.h>
> main()
> {
> 	mprotect((void *)((unsigned long)main & ~0xfff), 0x1000,
> 		 PROT_READ|PROT_WRITE|PROT_EXEC);
> }
> 
> qemu-x86_64 even complains about an "Unsupported syscall: 221", while
> the same 64-bit binary works fine with 0.9.1 (I don't recall anymore if
> it worked recently with SVN head).

Some clarification: mprotect is fine with qemu-x86_64, that syscall
warning is another, unrelated issue (it pops up with every x86_64
application in userland emu).

That leaves us with mprotect being broken in qemu-i386 on x86_64 hosts.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux