On Wednesday 10 January 2007 01:22, darran kartaschew wrote: > > Hi Guys, > I'm having some issues with rewriting a simple malloc() function to be > with FreeBSD (AMD64). This is part of porting an application from > Linux > to FreeBSD. > After pulling my hair out for a while, I've found that the sbrk() > system call just returns "45 - Operation Not Supported" error, > irrespective of the parameters passed to it. (I've found the source > for sbrk() and see that it's not implemented). > So I decided to try using mmap() instead. All memory allocations don't > have to be continuous, so mmap() will suffice. The problem is I'm > getting an invalid file handle error? According to the man page, if > you > use MAP_ANON you're just allocating a block of memory without linking > to a file, and a handle of -1 should be supplied... Any way code is as > follows: > memInit: > mov r4, 0 ; don't care where the memory is allocated > mov r5, 1048576 ; alloc 1MB > mov r3, 3 ; RW access to memory > mov r2, 4096 ; MAP_ANON - not a file > mov r8d, -1 ; -1 for file handle if using MAP_ANON > mov r9, 0 ; ignored for MAP_ANON > mov r0, 197 ; mmap(); > syscall > mov qword [_mmap], r0 ; save address so we can release it on exit; > ret > It fails with an EBADF (9) ; Bad File Descriptor error... > Note: r0 = rax, r1 = rbx, r2 = rcx, r3 = rdx, r4 = rdi, r5 = rsi, r6 = > rbp, r7 = rsp. Various parameters for mmap() are found in mman.h>. > So does anyone have an example of a working call to mmap() or tell me > what's wrong with the above code? > I've done up a test C program that simple calls mmap(), after > tracing through the compiled C program using gdb I can't see that > I'm doing anything different to what gcc/glibc are doing? (except > the macro expansion that's in libc which adds an additional > 0 to the top of the stack). > PS. FASM 1.66 running on FreeBSD 6.1 (AMD64). > PPS. This is NOT a homework assignment! (tm) :P
Is there a particular reason you have to use assembly and not C? You can call C functions from assembly and vice versa. You also forgot to include one of MAP_SHARED or MAP_PRIVATE in your flags. -- John Baldwin _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
