diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/arm/mmap.S')
| -rw-r--r-- | sysdeps/unix/sysv/linux/arm/mmap.S | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/sysdeps/unix/sysv/linux/arm/mmap.S b/sysdeps/unix/sysv/linux/arm/mmap.S index f9a773fc68..fcff57c55d 100644 --- a/sysdeps/unix/sysv/linux/arm/mmap.S +++ b/sysdeps/unix/sysv/linux/arm/mmap.S @@ -26,10 +26,26 @@ ENTRY (__mmap) mmap() takes six, we need to build a parameter block and pass its address instead. The 386 port does a similar trick. */ - mov ip, sp - stmdb ip!, {a1-a4} - mov a1, ip + /* This code previously moved sp into ip and stored the args using + stmdb ip!, {a1-a4}. It did not modify sp, so the stack never had + to be restored after the syscall completed. It saved an + instruction and meant no stack cleanup work was required. + + This will not work in the case of a mmap call being interrupted + by a signal. If the signal handler uses any stack the arguments + to mmap will be trashed. The results of a restart of mmap are + then unpredictable. */ + + /* store args on the stack */ + stmdb sp!, {a1-a4} + + /* do the syscall */ + mov a1, sp swi SYS_ify (mmap) + + /* pop args off the stack. */ + add sp, sp, #16 + cmn r0, $4096 bhs PLTJMP(syscall_error); ret |