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Fixes in "new" mmap

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* mem.c (sys_mmap): Ensure unsigned expansion of tcp->u_arg[5].
Add page shift of offset for I386.
Use tcp->ext_arg[5] as offset for X32.
(sys_old_mmap): [X32] Remove this function, X32 doesn't use is.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2013-02-18 03:13:07 +01:00
parent 923255cbe8
commit 8dedb0dc96
2 changed files with 56 additions and 42 deletions
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49
mem.c
View File

@ -280,13 +280,8 @@ int sys_old_mmap(struct tcb *tcp)
int
sys_mmap(struct tcb *tcp)
{
long long offset = tcp->u_arg[5];
unsigned long long offset = (unsigned long) tcp->u_arg[5];
/* FIXME: why only SH64? i386 mmap2 syscall ends up
* in this function, but does not convert offset
* from pages to bytes. See test/mmap_offset_decode.c
* Why SH64 and i386 are handled differently?
*/
#if defined(SH64)
/*
* Old mmap differs from new mmap in specifying the
@ -295,8 +290,12 @@ sys_mmap(struct tcb *tcp)
* sees bytes in the printout.
*/
offset <<= PAGE_SHIFT;
#endif
#if defined(LINUX_MIPSN32)
#elif defined(I386)
/* Try test/mmap_offset_decode.c */
offset <<= 12; /* 4096 byte pages */
#elif defined(LINUX_MIPSN32) || defined(X32)
/* Try test/x32_mmap.c */
/* At least for X32 it definitely should not be page-shifted! */
offset = tcp->ext_arg[5];
#endif
return print_mmap(tcp, tcp->u_arg, offset);
@ -304,40 +303,6 @@ sys_mmap(struct tcb *tcp)
#endif /* !HAVE_LONG_LONG_OFF_T */
#if _LFS64_LARGEFILE || HAVE_LONG_LONG_OFF_T
# if defined(X32)
int sys_old_mmap(struct tcb *tcp)
{
long u_arg[6];
if (umoven(tcp, tcp->u_arg[0], sizeof(u_arg), (char *) u_arg) == -1)
return 0;
if (entering(tcp)) {
/* addr */
if (!u_arg[0])
tprints("NULL, ");
else
tprintf("%#lx, ", u_arg[0]);
/* len */
tprintf("%lu, ", u_arg[1]);
/* prot */
printflags(mmap_prot, u_arg[2], "PROT_???");
tprints(", ");
/* flags */
# ifdef MAP_TYPE
printxval(mmap_flags, u_arg[3] & MAP_TYPE, "MAP_???");
addflags(mmap_flags, u_arg[3] & ~MAP_TYPE);
# else
printflags(mmap_flags, u_arg[3], "MAP_???");
# endif
/* fd */
tprints(", ");
printfd(tcp, u_arg[4]);
/* offset */
tprintf(", %#lx", u_arg[5]);
}
return RVAL_HEX;
}
# endif
/* TODO: comment which arches use this routine.
* For one, does ALPHA on Linux use this??
* From code it seems that it might use 7 or 8 registers,

49
test/x32_mmap.c Normal file
View File

@ -0,0 +1,49 @@
// Test program which explores whether mmap's ofs parameter
// is 64-bit, and whether it needs to be shifted << PAGE_SHIFT.
// Apparently it is 64-bit and isn't shifted.
//
// Build: x86_64-gcc -static -Wall -ox32_mmap x32_mmap.c
// Typical output:
// 7f9390696000-7f93906a6000 r--s 12345670000 08:06 2224545 /etc/passwd
// ^^^^^^^^^^^
#define _GNU_SOURCE
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/syscall.h>
// Ensure we are compiling to 64 bits
struct bug { int t[sizeof(long) > 4 ? 1 : -1]; };
int main(int argc, char **argv)
{
long ofs = 0x12345670000; // fails if not page-aligned
errno = 0;
close(0);
if (open("/etc/passwd", O_RDONLY))
return 1;
long r = syscall(
(long) (__NR_mmap | 0x40000000), // make x32 call
(long) (0), // start
(long) (0x10000), // len
(long) (PROT_READ), // prot
(long) (MAP_SHARED), // flags
(long) (0), // fd
(long) (ofs) // ofs
);
printf("ret:0x%lx errno:%m\n", r);
char buf[16*1024];
sprintf(buf, "/proc/%d/maps", getpid());
int fd = open(buf, O_RDONLY);
if (fd > 0) {
int sz = read(fd, buf, sizeof(buf));
if (sz > 0)
write(1, buf, sz);
}
return 0;
}