| Message ID | 20230625231751.404120-4-bugaevc@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/5] htl: Let Mach place thread stacks | expand |
Applied, thanks! Sergey Bugaev, le lun. 26 juin 2023 02:17:50 +0300, a ecrit: > Zero address passed to mmap () typically means the caller doesn't have > any specific preferred address. Not so if MAP_FIXED is passed: in this > case 0 means literal 0. Fix this case to pass anywhere = 0 into vm_map. > > Also add some documentation. > > Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> > --- > sysdeps/mach/hurd/mmap.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/sysdeps/mach/hurd/mmap.c b/sysdeps/mach/hurd/mmap.c > index 5aa70083..33672cf6 100644 > --- a/sysdeps/mach/hurd/mmap.c > +++ b/sysdeps/mach/hurd/mmap.c > @@ -38,7 +38,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) > vm_prot_t vmprot, max_vmprot; > memory_object_t memobj; > vm_address_t mapaddr, mask; > - boolean_t copy; > + boolean_t copy, anywhere; > > mapaddr = (vm_address_t) addr; > > @@ -55,6 +55,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) > vmprot |= VM_PROT_EXECUTE; > > copy = ! (flags & MAP_SHARED); > + anywhere = ! (flags & MAP_FIXED); > > #ifdef __LP64__ > if ((addr == NULL) && (prot & PROT_EXEC) > @@ -141,9 +142,12 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) > if (copy) > max_vmprot = VM_PROT_ALL; > > + /* When ANYWHERE is true but the caller has provided a preferred address, > + try mapping at that address with anywhere = 0 first. If this fails, > + we'll retry with anywhere = 1 below. */ > err = __vm_map (__mach_task_self (), > &mapaddr, (vm_size_t) len, mask, > - mapaddr == 0, > + anywhere && (mapaddr == 0), > memobj, (vm_offset_t) offset, > copy, vmprot, max_vmprot, > copy ? VM_INHERIT_COPY : VM_INHERIT_SHARE); > @@ -165,7 +169,10 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) > } > else > { > + /* This mmap call is allowed to allocate anywhere, */ > if (mapaddr != 0 && (err == KERN_NO_SPACE || err == KERN_INVALID_ADDRESS)) > + /* ...but above, we tried allocating at the specific address, > + and failed to. Now try again, with anywhere = 1 this time. */ > err = __vm_map (__mach_task_self (), > &mapaddr, (vm_size_t) len, mask, > 1, memobj, (vm_offset_t) offset, > -- > 2.41.0 > >
diff --git a/sysdeps/mach/hurd/mmap.c b/sysdeps/mach/hurd/mmap.c index 5aa70083..33672cf6 100644 --- a/sysdeps/mach/hurd/mmap.c +++ b/sysdeps/mach/hurd/mmap.c @@ -38,7 +38,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) vm_prot_t vmprot, max_vmprot; memory_object_t memobj; vm_address_t mapaddr, mask; - boolean_t copy; + boolean_t copy, anywhere; mapaddr = (vm_address_t) addr; @@ -55,6 +55,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) vmprot |= VM_PROT_EXECUTE; copy = ! (flags & MAP_SHARED); + anywhere = ! (flags & MAP_FIXED); #ifdef __LP64__ if ((addr == NULL) && (prot & PROT_EXEC) @@ -141,9 +142,12 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) if (copy) max_vmprot = VM_PROT_ALL; + /* When ANYWHERE is true but the caller has provided a preferred address, + try mapping at that address with anywhere = 0 first. If this fails, + we'll retry with anywhere = 1 below. */ err = __vm_map (__mach_task_self (), &mapaddr, (vm_size_t) len, mask, - mapaddr == 0, + anywhere && (mapaddr == 0), memobj, (vm_offset_t) offset, copy, vmprot, max_vmprot, copy ? VM_INHERIT_COPY : VM_INHERIT_SHARE); @@ -165,7 +169,10 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) } else { + /* This mmap call is allowed to allocate anywhere, */ if (mapaddr != 0 && (err == KERN_NO_SPACE || err == KERN_INVALID_ADDRESS)) + /* ...but above, we tried allocating at the specific address, + and failed to. Now try again, with anywhere = 1 this time. */ err = __vm_map (__mach_task_self (), &mapaddr, (vm_size_t) len, mask, 1, memobj, (vm_offset_t) offset,
Zero address passed to mmap () typically means the caller doesn't have any specific preferred address. Not so if MAP_FIXED is passed: in this case 0 means literal 0. Fix this case to pass anywhere = 0 into vm_map. Also add some documentation. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> --- sysdeps/mach/hurd/mmap.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)