Initialize VirtualMem

1 files changed, 18 insertions, 0 deletions

diff --git a/zjit.c b/zjit.c
index 69b8fc6b67..d0034e7bf1 100644
--- a/zjit.c
+++ b/zjit.c
@@ -31,6 +31,24 @@
 
 #include <errno.h>
 
+uint32_t
+rb_zjit_get_page_size(void)
+{
+#if defined(_SC_PAGESIZE)
+    long page_size = sysconf(_SC_PAGESIZE);
+    if (page_size <= 0) rb_bug("zjit: failed to get page size");
+
+    // 1 GiB limit. x86 CPUs with PDPE1GB can do this and anything larger is unexpected.
+    // Though our design sort of assume we have fine grained control over memory protection
+    // which require small page sizes.
+    if (page_size > 0x40000000l) rb_bug("zjit page size too large");
+
+    return (uint32_t)page_size;
+#else
+#error "YJIT supports POSIX only for now"
+#endif
+}
+
 // Address space reservation. Memory pages are mapped on an as needed basis.
 // See the Rust mm module for details.
 uint8_t *