diff options
Diffstat (limited to 'lib/system/alloc.nim')
| -rwxr-xr-x | lib/system/alloc.nim | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/lib/system/alloc.nim b/lib/system/alloc.nim index f3474a527..981dac977 100755 --- a/lib/system/alloc.nim +++ b/lib/system/alloc.nim @@ -14,6 +14,11 @@ # ------------ platform specific chunk allocation code ----------------------- +# some platforms have really weird unmap behaviour: unmap(blockStart, PageSize) +# really frees the whole block. Happens for Linux/PowerPC for example. Amd64 +# and x86 are safe though: +const weirdUnmap = not (defined(amd64) or defined(i386)) + when defined(posix): const PROT_READ = 1 # page can be read @@ -425,7 +430,7 @@ proc freeBigChunk(a: var TMemRegion, c: PBigChunk) = excl(a.chunkStarts, pageIndex(c)) c = cast[PBigChunk](le) - if c.size < ChunkOsReturn: + if c.size < ChunkOsReturn or weirdUnmap: incl(a, a.chunkStarts, pageIndex(c)) updatePrevSize(a, c, c.size) ListAdd(a.freeChunksList, c) @@ -697,8 +702,16 @@ proc deallocOsPages(a: var TMemRegion) = # we free every 'ordinarily' allocated page by iterating over the page bits: for p in elements(a.chunkStarts): var page = cast[PChunk](p shl pageShift) - var size = if page.size < PageSize: PageSize else: page.size - osDeallocPages(page, size) + when not weirdUnmap: + var size = if page.size < PageSize: PageSize else: page.size + osDeallocPages(page, size) + else: + # Linux on PowerPC for example frees MORE than asked if 'munmap' + # receives the start of an originally mmap'ed memory block. This is not + # too bad, but we must not access 'page.size' then as that could trigger + # a segfault. But we don't need to access 'page.size' here anyway, + # because calling munmap with PageSize suffices: + osDeallocPages(page, PageSize) # And then we free the pages that are in use for the page bits: llDeallocAll(a) |