[PATCH RFC v3 1/2] mm: Add personality flag to limit address to 47 bits
Charlie Jenkins <[email protected]>
| Newsgroups | gmane.linux.ports.ppc64.devel,gmane.linux.kernel.cross-arch,gmane.linux.kernel,gmane.linux.ports.alpha,gmane.linux.kernel.arc,gmane.linux.ports.arm.kernel,gmane.linux.ports.mips,gmane.linux.ports.parisc,gmane.linux.ports.sh.devel,gmane.linux.ports.sparc,gmane.linux.kernel.mm |
|---|---|
| Message-ID | <[email protected]> |
Create a personality flag ADDR_LIMIT_47BIT to support applications that wish to transition from running in environments that support at most 47-bit VAs to environments that support larger VAs. This personality can be set to cause all allocations to be below the 47-bit boundary. Using MAP_FIXED with mmap() will bypass this restriction. Signed-off-by: Charlie Jenkins <[email protected]> --- include/uapi/linux/personality.h | 1 + mm/mmap.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/include/uapi/linux/personality.h b/include/uapi/linux/personality.h index 49796b7756af..cd3b8c154d9b 100644 --- a/include/uapi/linux/personality.h +++ b/include/uapi/linux/personality.h @@ -22,6 +22,7 @@ enum { WHOLE_SECONDS = 0x2000000, STICKY_TIMEOUTS = 0x4000000, ADDR_LIMIT_3GB = 0x8000000, + ADDR_LIMIT_47BIT = 0x10000000, }; /* diff --git a/mm/mmap.c b/mm/mmap.c index d0dfc85b209b..a5c7544853e5 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1766,6 +1766,9 @@ unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) { unsigned long addr; + if (current->personality & ADDR_LIMIT_47BIT) + info->high_limit = MIN(info->high_limit, BIT(47) - 1); + if (info->flags & VM_UNMAPPED_AREA_TOPDOWN) addr = unmapped_area_topdown(info); else -- 2.45.0