Issue #1571 - Remove JEMALLOC_USES_MAP_ALIGN and fix 48-bit addressing on SunOS AMD64.

The JEMALLOC_USES_MAP_ALIGN code has turned out to be worse than useless, and in fact it breaks 64-bit SunOS. It's very old and turned out not to be needed anymore because the way the memory allocator works has changed since it was implemented. It prevented a fix I tried for 48-bit addressing from working properly. However, without either this code or the 48-bit addressing fix, the 64-bit version won't even start, which is why I thought the code was still needed.

https://bugzilla.mozilla.org/show_bug.cgi?id=457189

https://hg.mozilla.org/mozilla-central/rev/a26c500b98ab

The 48-bit addressing fix is based on code found here:

https://github.com/OpenIndiana/oi-userland/blob/oi/hipster/components/web/firefox/patches/patch-js_src_gc_Memory.cpp.patch

I already applied these changes to js/src/gc/Memory.cpp, but as I was looking through jemalloc.c I saw that there were very similar ifdefs for Linux on SPARC as the ones I'd had to enaable in Memory.cpp, but for whatever reason the patches I found didn't touch them. So I tried doing for jemalloc.c what was already done for Memory.cpp, and it worked (but only after I removed the map align code).

1 files changed, 4 insertions, 42 deletions

diff --git a/memory/mozjemalloc/jemalloc.c b/memory/mozjemalloc/jemalloc.c
index 47a5a9f5c..86864e1cd 100644
--- a/memory/mozjemalloc/jemalloc.c
+++ b/memory/mozjemalloc/jemalloc.c
@@ -357,10 +357,6 @@ void *_mmap(void *addr, size_t length, int prot, int flags,
 #endif
 #endif
 
-#if defined(MOZ_MEMORY_SOLARIS) && defined(MAP_ALIGN) && !defined(JEMALLOC_NEVER_USES_MAP_ALIGN)
-#define JEMALLOC_USES_MAP_ALIGN	 /* Required on Solaris 10. Might improve performance elsewhere. */
-#endif
-
 #ifndef __DECONST
 #define __DECONST(type, var) ((type)(uintptr_t)(const void *)(var))
 #endif
@@ -1940,33 +1936,12 @@ pages_unmap(void *addr, size_t size)
 	}
 }
 #else
-#ifdef JEMALLOC_USES_MAP_ALIGN
-static void *
-pages_map_align(size_t size, size_t alignment)
-{
-	void *ret;
-
-	/*
-	 * We don't use MAP_FIXED here, because it can cause the *replacement*
-	 * of existing mappings, and we only want to create new mappings.
-	 */
-	ret = mmap((void *)alignment, size, PROT_READ | PROT_WRITE,
-		MAP_PRIVATE | MAP_NOSYNC | MAP_ALIGN | MAP_ANON, -1, 0);
-	assert(ret != NULL);
-
-	if (ret == MAP_FAILED)
-		ret = NULL;
-	else
-		MozTagAnonymousMemory(ret, size, "jemalloc");
-	return (ret);
-}
-#endif
 
 static void *
 pages_map(void *addr, size_t size)
 {
 	void *ret;
-#if defined(__ia64__) || (defined(__sparc__) && defined(__arch64__) && defined(__linux__))
+#if defined(__ia64__) || (defined(__sparc__) && defined(__arch64__) && defined(__linux__)) || (defined(__sun) && defined(__x86_64__))
         /*
          * The JS engine assumes that all allocated pointers have their high 17 bits clear,
          * which ia64's mmap doesn't support directly. However, we can emulate it by passing
@@ -1987,7 +1962,7 @@ pages_map(void *addr, size_t size)
 	}
 #endif
 
-#if defined(__sparc__) && defined(__arch64__) && defined(__linux__)
+#if defined(__sparc__) && defined(__arch64__) && defined(__linux__) || (defined(__sun) && defined(__x86_64__))
     const uintptr_t start = 0x0000070000000000ULL;
     const uintptr_t end   = 0x0000800000000000ULL;
 
@@ -2021,7 +1996,7 @@ pages_map(void *addr, size_t size)
 	if (ret == MAP_FAILED) {
 		ret = NULL;
 	}
-#if defined(__ia64__) || (defined(__sparc__) && defined(__arch64__) && defined(__linux__))
+#if defined(__ia64__) || (defined(__sparc__) && defined(__arch64__) && defined(__linux__)) || (defined(__sun) && defined(__x86_64__))
         /*
          * If the allocated memory doesn't have its upper 17 bits clear, consider it
          * as out of memory.
@@ -2054,7 +2029,7 @@ pages_map(void *addr, size_t size)
 		MozTagAnonymousMemory(ret, size, "jemalloc");
 	}
 
-#if defined(__ia64__) || (defined(__sparc__) && defined(__arch64__) && defined(__linux__))
+#if defined(__ia64__) || (defined(__sparc__) && defined(__arch64__) && defined(__linux__)) || (defined(__sun) && defined(__x86_64__))
 	assert(ret == NULL || (!check_placement && ret != NULL)
 	    || (check_placement && ret == addr));
 #else
@@ -2305,9 +2280,6 @@ chunk_alloc_mmap_slow(size_t size, size_t alignment)
 static void *
 chunk_alloc_mmap(size_t size, size_t alignment)
 {
-#ifdef JEMALLOC_USES_MAP_ALIGN
-        return pages_map_align(size, alignment);
-#else
         void *ret;
         size_t offset;
 
@@ -2335,7 +2307,6 @@ chunk_alloc_mmap(size_t size, size_t alignment)
 
         assert(ret != NULL);
         return (ret);
-#endif
 }
 
 bool
@@ -5341,15 +5312,6 @@ MALLOC_OUT:
 
 	recycled_size = 0;
 
-#ifdef JEMALLOC_USES_MAP_ALIGN
-	/*
-	 * When using MAP_ALIGN, the alignment parameter must be a power of two
-	 * multiple of the system pagesize, or mmap will fail.
-	 */
-	assert((chunksize % pagesize) == 0);
-	assert((1 << (ffs(chunksize / pagesize) - 1)) == (chunksize/pagesize));
-#endif
-
 	/* Various sanity checks that regard configuration. */
 	assert(quantum >= sizeof(void *));
 	assert(quantum <= pagesize);