> Is the size of the virtual address space hole constant though (and will it > remain constant)?
The kernel sources say that it's constant and with this position for SPARC-T4 and later. It's different (larger hole) for SPARC-T3 and earlier but I cannot really test. I don't think that it will change for a given processor. > E.g. on powerpc64 or aarch64 there are in each case like 4-5 different VA > size configurations over the last 10+ years of kernel history and > configuration options and fortunately all that is hidden inside of libasan, > if you have older gcc and run into an unsupported VA configuration, all it > takes is update libasan to one that supports it and binaries continue to > work. But a few targets have hardcoded VA size in TARGET_ASAN_SHADOW_OFFSET too. > Could libasan initialization if it detects just PROT_NONE mmap from the end > of hole to the start of the region it really supports (and fail if that > fails), so that backward compatibility is ensured? I'll investigate how targets supporting multiple VA size behave, but I don't have access to a large range of SPARC machines... > Also, don't you need some corresponding libsanitizer changes? Of course, just merged. -- Eric Botcazou
