svn commit: r364659 - stable/12/sys/compat/linux

[Edward Tomasz Napierala]

Author: trasz
Date: Mon Aug 24 12:26:49 2020
New Revision: 364659
URL: https://svnweb.freebsd.org/changeset/base/364659

Log:
  MFC r357076:
  
  Make linux(4) handle MAP_32BIT.
  
  This unbreaks Mono (mono-devel-4.6.2.7+dfsg-1ubuntu1 from Ubuntu Bionic);
  previously would crash on "amd64_is_imm32" assert.
  
  Sponsored by:	The FreeBSD Foundation

Modified:
  stable/12/sys/compat/linux/linux_mmap.c
  stable/12/sys/compat/linux/linux_mmap.h
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/compat/linux/linux_mmap.c
==============================================================================
--- stable/12/sys/compat/linux/linux_mmap.c	Mon Aug 24 12:23:55 2020	(r364658)
+++ stable/12/sys/compat/linux/linux_mmap.c	Mon Aug 24 12:26:49 2020	(r364659)
@@ -113,7 +113,15 @@ linux_mmap_common(struct thread *td, uintptr_t addr, s
 	if (flags & LINUX_MAP_GROWSDOWN)
 		bsd_flags |= MAP_STACK;
 
+#if defined(__amd64__)
 	/*
+	 * According to the Linux mmap(2) man page, "MAP_32BIT flag
+	 * is ignored when MAP_FIXED is set."
+	 */
+	if ((flags & LINUX_MAP_32BIT) && (flags & LINUX_MAP_FIXED) == 0)
+		bsd_flags |= MAP_32BIT;
+
+	/*
 	 * PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
 	 * on Linux/i386 if the binary requires executable stack.
 	 * We do this only for IA32 emulation as on native i386 this is does not
@@ -121,7 +129,6 @@ linux_mmap_common(struct thread *td, uintptr_t addr, s
 	 *
 	 * XXX. Linux checks that the file system is not mounted with noexec.
 	 */
-#if defined(__amd64__)
 	linux_fixup_prot(td, &prot);
 #endif
 

Modified: stable/12/sys/compat/linux/linux_mmap.h
==============================================================================
--- stable/12/sys/compat/linux/linux_mmap.h	Mon Aug 24 12:23:55 2020	(r364658)
+++ stable/12/sys/compat/linux/linux_mmap.h	Mon Aug 24 12:26:49 2020	(r364659)
@@ -39,6 +39,7 @@
 #define	LINUX_MAP_PRIVATE	0x0002
 #define	LINUX_MAP_FIXED		0x0010
 #define	LINUX_MAP_ANON		0x0020
+#define	LINUX_MAP_32BIT		0x0040
 #define	LINUX_MAP_GROWSDOWN	0x0100
 
 #define	LINUX_PROT_GROWSDOWN	0x01000000