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src: simplify large pages mapping code

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* Introduce `OnScopeLeave` handler for cleaning up mmap()ed range(s).
* Factor out failure scenario at the bottom of the function with
  `fail` label for use with `goto`.
* Do not allocate temporary range (`nmem`) on FreeBSD, because it is
  not used.

The intention is that the steps involved in re-mapping to large pages
become more clearly visible.

Signed-off-by: Gabriel Schulhof <gabriel.schulhof@intel.com>
Co-authored-by: Ben Noordhuis <info@bnoordhuis.nl>
PR-URL: https://github.com/nodejs/node/pull/32396
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: David Carlier <devnexen@gmail.com>
This commit is contained in:
Gabriel Schulhof
2020-03-20 12:00:27 -07:00
parent 436c71db66
commit fa3fd78c88
1 changed files with 25 additions and 56 deletions
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81
src/large_pages/node_large_page.cc
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@@ -339,20 +339,23 @@ __attribute__((__noinline__))
MoveTextRegionToLargePages(const text_region& r) {
void* nmem = nullptr;
void* tmem = nullptr;
int ret = 0;
size_t size = r.to - r.from;
void* start = r.from;
size_t size = r.to - r.from;
// Allocate temporary region preparing for copy.
auto free_mems = OnScopeLeave([&nmem, &tmem, size]() {
if (nmem != nullptr && nmem != MAP_FAILED && munmap(nmem, size) == -1)
PrintSystemError(errno);
if (tmem != nullptr && tmem != MAP_FAILED && munmap(tmem, size) == -1)
PrintSystemError(errno);
});
#if !defined (__FreeBSD__)
// Allocate temporary region and back up the code we will re-map.
nmem = mmap(nullptr, size,
PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (nmem == MAP_FAILED) {
PrintSystemError(errno);
return -1;
}
if (nmem == MAP_FAILED) goto fail;
memcpy(nmem, r.from, size);
#endif
#if defined(__linux__)
// We already know the original page is r-xp
@@ -362,32 +365,15 @@ MoveTextRegionToLargePages(const text_region& r) {
tmem = mmap(start, size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1 , 0);
if (tmem == MAP_FAILED) {
PrintSystemError(errno);
return -1;
}
ret = madvise(tmem, size, 14 /* MADV_HUGEPAGE */);
if (ret == -1) {
PrintSystemError(errno);
ret = munmap(tmem, size);
if (ret == -1) {
PrintSystemError(errno);
}
if (-1 == munmap(nmem, size)) PrintSystemError(errno);
return -1;
}
if (tmem == MAP_FAILED) goto fail;
if (madvise(tmem, size, 14 /* MADV_HUGEPAGE */) == -1) goto fail;
memcpy(start, nmem, size);
#elif defined(__FreeBSD__)
tmem = mmap(start, size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED |
MAP_ALIGNED_SUPER, -1 , 0);
if (tmem == MAP_FAILED) {
PrintSystemError(errno);
if (-1 == munmap(nmem, size)) PrintSystemError(errno);
return -1;
}
if (tmem == MAP_FAILED) goto fail;
#elif defined(__APPLE__)
// There is not enough room to reserve the mapping close
// to the region address so we content to give a hint
@@ -398,37 +384,20 @@ MoveTextRegionToLargePages(const text_region& r) {
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS,
VM_FLAGS_SUPERPAGE_SIZE_2MB, 0);
if (tmem == MAP_FAILED) {
PrintSystemError(errno);
if (-1 == munmap(nmem, size)) PrintSystemError(errno);
return -1;
}
if (tmem == MAP_FAILED) goto fail;
memcpy(tmem, nmem, size);
ret = mprotect(start, size, PROT_READ | PROT_WRITE | PROT_EXEC);
if (ret == -1) {
PrintSystemError(errno);
ret = munmap(tmem, size);
if (ret == -1) {
PrintSystemError(errno);
}
if (-1 == munmap(nmem, size)) PrintSystemError(errno);
return -1;
}
if (mprotect(start, size, PROT_READ | PROT_WRITE | PROT_EXEC) == -1)
goto fail;
memcpy(start, tmem, size);
#endif
ret = mprotect(start, size, PROT_READ | PROT_EXEC);
if (ret == -1) {
PrintSystemError(errno);
ret = munmap(tmem, size);
if (ret == -1) {
PrintSystemError(errno);
}
if (-1 == munmap(nmem, size)) PrintSystemError(errno);
return -1;
}
if (-1 == munmap(nmem, size)) PrintSystemError(errno);
return ret;
if (mprotect(start, size, PROT_READ | PROT_EXEC) == -1) goto fail;
// We need not `munmap(tmem, size)` in the above `OnScopeLeave` on success.
tmem = nullptr;
return 0;
fail:
PrintSystemError(errno);
return -1;
}
#endif // defined(NODE_ENABLE_LARGE_CODE_PAGES) && NODE_ENABLE_LARGE_CODE_PAGES