opcache find best candidate near .text segment for large maps on FreeBSD.

Follow up on #8890 using similar workflow, we go through the php binary mapping per address boundaries.

Closes #8908.

Author: devnexen

NEWS

@@ -39,8 +39,9 @@ PHP                                                                        NEWS
     for macOs Instrument. (David Carlier)
   . Fixed bug GH-8030 (Segfault with JIT and large match/switch statements).
     (Arnaud)
-  . JIT support improvement for macOs for segments and executable permission
+  . Added JIT support improvement for macOs for segments and executable permission
     bit handling. (David Carlier)
+  . Added JIT buffer allocation near the .text section on FreeNSD. (David Carlier)
 
 - PCRE:
   . Updated bundled libpcre to 10.40. (cmb)

ext/opcache/shared_alloc_mmap.c

@@ -39,17 +39,21 @@
 # define MAP_ANONYMOUS MAP_ANON
 #endif
 #if defined(MAP_ALIGNED_SUPER)
+# include <sys/types.h>
+# include <sys/sysctl.h>
+# include <sys/user.h>
 # define MAP_HUGETLB MAP_ALIGNED_SUPER
 #endif
 
-#if defined(__linux__) && (defined(__x86_64__) || defined (__aarch64__))
+#if (defined(__linux__) || defined(__FreeBSD__)) && (defined(__x86_64__) || defined (__aarch64__))
 static void *find_prefered_mmap_base(size_t requested_size)
 {
-	FILE *f;
 	size_t huge_page_size = 2 * 1024 * 1024;
 	uintptr_t last_free_addr = 0;
 	uintptr_t last_candidate = (uintptr_t)MAP_FAILED;
 	uintptr_t start, end, text_start = 0;
+#if defined(__linux__)
+	FILE *f;
 	char buffer[MAXPATHLEN];
 
 	f = fopen("/proc/self/maps", "r");
@@ -89,6 +93,59 @@ static void *find_prefered_mmap_base(size_t requested_size)
 
 	}
 	fclose(f);
+#elif defined(__FreeBSD__)
+	size_t s = 0;
+	int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_VMMAP, getpid()};
+	if (sysctl(mib, 4, NULL, &s, NULL, 0) == 0) {
+		s = s * 4 / 3;
+		void *addr = mmap(NULL, s, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
+		if (addr != MAP_FAILED) {
+			if (sysctl(mib, 4, addr, &s, NULL, 0) == 0) {
+				start = (uintptr_t)addr;
+				end = start + s;
+				while (start < end) {
+					struct kinfo_vmentry *entry = (struct kinfo_vmentry *)start;
+					size_t sz = entry->kve_structsize;
+					if (sz == 0) {
+						break;
+					}
+					uintptr_t e_start = entry->kve_start;
+					uintptr_t e_end = entry->kve_end;
+					if ((uintptr_t)execute_ex >= e_start) {
+						/* the current segment lays before PHP .text segment or PHP .text segment itself */
+						if (last_free_addr + requested_size <= e_start) {
+							last_candidate = last_free_addr;
+						}
+						if ((uintptr_t)execute_ex < e_end) {
+							/* the current segment is PHP .text segment itself */
+							if (last_candidate != (uintptr_t)MAP_FAILED) {
+								if (e_end - last_candidate < UINT32_MAX) {
+									/* we have found a big enough hole before the text segment */
+									break;
+								}
+								last_candidate = (uintptr_t)MAP_FAILED;
+							}
+							text_start = e_start;
+						}
+					} else {
+						/* the current segment lays after PHP .text segment */
+						if (last_free_addr + requested_size - text_start > UINT32_MAX) {
+							/* the current segment and the following segments lay too far from PHP .text segment */
+							break;
+						}
+						if (last_free_addr + requested_size <= e_start) {
+							last_candidate = last_free_addr;
+							break;
+						}
+					}
+					last_free_addr = ZEND_MM_ALIGNED_SIZE_EX(e_end, huge_page_size);
+					start += sz;
+				}
+			}
+			munmap(addr, s);
+		}
+	}
+#endif
 
 	return (void*)last_candidate;
 }
@@ -109,7 +166,7 @@ static int create_segments(size_t requested_size, zend_shared_segment ***shared_
 #ifdef PROT_MAX
 	flags |= PROT_MAX(PROT_READ | PROT_WRITE | PROT_EXEC);
 #endif
-#if defined(__linux__) && (defined(__x86_64__) || defined (__aarch64__))
+#if (defined(__linux__) || defined(__FreeBSD__)) && (defined(__x86_64__) || defined (__aarch64__))
 	void *hint = find_prefered_mmap_base(requested_size);
 	if (hint != MAP_FAILED) {
 # ifdef MAP_HUGETLB