From d4a17c3a253d02c2ebf2315e71a29cb740278977 Mon Sep 17 00:00:00 2001 From: Simon Marlow Date: Wed, 10 Dec 2008 11:57:51 +0000 Subject: [PATCH] On FreeBSD, try MAP_FIXED if ordinary mmap() fails to give us suitable memory This appears to be necessary on FreeBSD. It might be necessary on other OSs too, but I'm being cautious because using MAP_FIXED can lead to crashes by overwriting existing mappings, and we have no (easy) way to prevent that. --- rts/Linker.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/rts/Linker.c b/rts/Linker.c index 2119262..ac06cda 100644 --- a/rts/Linker.c +++ b/rts/Linker.c @@ -1302,6 +1302,7 @@ mmapForLinker (size_t bytes, nat flags, int fd) void *map_addr = NULL; void *result; int pagesize, size; + static nat fixed = 0; pagesize = getpagesize(); size = ROUND_UP(bytes, pagesize); @@ -1315,10 +1316,11 @@ mmap_again: #endif result = mmap(map_addr, size, PROT_EXEC|PROT_READ|PROT_WRITE, - MAP_PRIVATE|TRY_MAP_32BIT|flags, fd, 0); + MAP_PRIVATE|TRY_MAP_32BIT|fixed|flags, fd, 0); if (result == MAP_FAILED) { - sysErrorBelch("mmap"); + sysErrorBelch("mmap %lu bytes at %p",(lnat)size,map_addr); + errorBelch("Try specifying an address with +RTS -xm -RTS"); stg_exit(EXIT_FAILURE); } @@ -1329,8 +1331,16 @@ mmap_again: } else { if ((W_)result > 0x80000000) { // oops, we were given memory over 2Gb - // ... try allocating memory somewhere else?; - barf("loadObj: failed to mmap() memory below 2Gb; asked for %lu bytes at %p, got %p. Try specifying an address with +RTS -xm -RTS", size, map_addr, result); +#if defined(freebsd_HOST_OS) + // Some platforms require MAP_FIXED. This is normally + // a bad idea, because MAP_FIXED will overwrite + // existing mappings. + munmap(result,size); + fixed = MAP_FIXED; + goto mmap_again; +#else + barf("loadObj: failed to mmap() memory below 2Gb; asked for %lu bytes at %p. Try specifying an address with +RTS -xm -RTS", size, map_addr, result); +#endif } else { // hmm, we were given memory somewhere else, but it's // still under 2Gb so we can use it. Next time, ask -- 1.7.10.4