diff options
Diffstat (limited to 'src/runtime/mpagealloc.go')
| -rw-r--r-- | src/runtime/mpagealloc.go | 60 |
1 files changed, 7 insertions, 53 deletions
diff --git a/src/runtime/mpagealloc.go b/src/runtime/mpagealloc.go index 10d547296e..572e6a9bc5 100644 --- a/src/runtime/mpagealloc.go +++ b/src/runtime/mpagealloc.go @@ -182,6 +182,10 @@ type pageAlloc struct { // runtime segmentation fault, we get a much friendlier out-of-bounds // error. // + // To iterate over a summary level, use inUse to determine which ranges + // are currently available. Otherwise one might try to access + // memory which is only Reserved which may result in a hard fault. + // // We may still get segmentation faults < len since some of that // memory may not be committed yet. summary [summaryLevels][]pallocSum @@ -212,12 +216,9 @@ type pageAlloc struct { // making the impact on BSS too high (note the L1 is stored directly // in pageAlloc). // - // summary[len(s.summary)-1][i] should always be checked, at least - // for a zero max value, before accessing chunks[i]. It's possible the - // bitmap at that index is mapped in and zeroed, indicating that it - // contains free space, but in actuality it is unused since its - // corresponding summary was never updated. Tests may ignore this - // and assume the zero value (and that it is mapped). + // To iterate over the bitmap, use inUse to determine which ranges + // are currently available. Otherwise one might iterate over unused + // ranges. // // TODO(mknyszek): Consider changing the definition of the bitmap // such that 1 means free and 0 means in-use so that summaries and @@ -297,53 +298,6 @@ func (s *pageAlloc) init(mheapLock *mutex, sysStat *uint64) { s.mheapLock = mheapLock } -// extendMappedRegion ensures that all the memory in the range -// [base+nbase, base+nlimit) is in the Ready state. -// base must refer to the beginning of a memory region in the -// Reserved state. extendMappedRegion assumes that the region -// [base+mbase, base+mlimit) is already mapped. -// -// Note that extendMappedRegion only supports extending -// mappings in one direction. Therefore, -// nbase < mbase && nlimit > mlimit is an invalid input -// and this function will throw. -func extendMappedRegion(base unsafe.Pointer, mbase, mlimit, nbase, nlimit uintptr, sysStat *uint64) { - if uintptr(base)%physPageSize != 0 { - print("runtime: base = ", base, "\n") - throw("extendMappedRegion: base not page-aligned") - } - // Round the offsets to a physical page. - mbase = alignDown(mbase, physPageSize) - nbase = alignDown(nbase, physPageSize) - mlimit = alignUp(mlimit, physPageSize) - nlimit = alignUp(nlimit, physPageSize) - - // If none of the region is mapped, don't bother - // trying to figure out which parts are. - if mlimit-mbase != 0 { - // Determine which part of the region actually needs - // mapping. - if nbase < mbase && nlimit > mlimit { - // TODO(mknyszek): Consider supporting this case. It can't - // ever happen currently in the page allocator, but may be - // useful in the future. Also, it would make this function's - // purpose simpler to explain. - throw("mapped region extended in two directions") - } else if nbase < mbase && nlimit <= mlimit { - nlimit = mbase - } else if nbase >= mbase && nlimit > mlimit { - nbase = mlimit - } else { - return - } - } - - // Transition from Reserved to Ready. - rbase := add(base, nbase) - sysMap(rbase, nlimit-nbase, sysStat) - sysUsed(rbase, nlimit-nbase) -} - // compareSearchAddrTo compares an address against s.searchAddr in a linearized // view of the address space on systems with discontinuous process address spaces. // This linearized view is the same one generated by chunkIndex and arenaIndex, |