Restore patch removed in r15104

split-flush_old_exec-into-two-functions.patch also modifies
binfmt_elf_fdpic and must be applied on top of
fdpic-respect-pt_gnu_stack-exec-protection-markings-when-creating-nommu-stack.patch

Don't mention it in the changelog since it has no actual effect on
Debian kernels.


svn path=/dists/trunk/linux-2.6/; revision=15105

2 files changed, 106 insertions, 0 deletions

diff --git a/debian/patches/bugfix/all/fdpic-respect-pt_gnu_stack-exec-protection-markings-when-creating-nommu-stack.patch b/debian/patches/bugfix/all/fdpic-respect-pt_gnu_stack-exec-protection-markings-when-creating-nommu-stack.patch
new file mode 100644
index 000000000000..ba5e8844a0a9
--- /dev/null
+++ b/debian/patches/bugfix/all/fdpic-respect-pt_gnu_stack-exec-protection-markings-when-creating-nommu-stack.patch
@@ -0,0 +1,105 @@
+From 04e4f2b18c8de1389d1e00fef0f42a8099910daf Mon Sep 17 00:00:00 2001
+From: Mike Frysinger <vapier@gentoo.org>
+Date: Wed, 6 Jan 2010 17:23:17 +0000
+Subject: FDPIC: Respect PT_GNU_STACK exec protection markings when creating NOMMU stack
+
+From: Mike Frysinger <vapier@gentoo.org>
+
+commit 04e4f2b18c8de1389d1e00fef0f42a8099910daf upstream.
+
+The current code will load the stack size and protection markings, but
+then only use the markings in the MMU code path.  The NOMMU code path
+always passes PROT_EXEC to the mmap() call.  While this doesn't matter
+to most people whilst the code is running, it will cause a pointless
+icache flush when starting every FDPIC application.  Typically this
+icache flush will be of a region on the order of 128KB in size, or may
+be the entire icache, depending on the facilities available on the CPU.
+
+In the case where the arch default behaviour seems to be desired
+(EXSTACK_DEFAULT), we probe VM_STACK_FLAGS for VM_EXEC to determine
+whether we should be setting PROT_EXEC or not.
+
+For arches that support an MPU (Memory Protection Unit - an MMU without
+the virtual mapping capability), setting PROT_EXEC or not will make an
+important difference.
+
+It should be noted that this change also affects the executability of
+the brk region, since ELF-FDPIC has that share with the stack.  However,
+this is probably irrelevant as NOMMU programs aren't likely to use the
+brk region, preferring instead allocation via mmap().
+
+Signed-off-by: Mike Frysinger <vapier@gentoo.org>
+Signed-off-by: David Howells <dhowells@redhat.com>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
+
+---
+ arch/blackfin/include/asm/page.h |    5 +++++
+ arch/frv/include/asm/page.h      |    2 --
+ fs/binfmt_elf_fdpic.c            |   13 +++++++++++--
+ 3 files changed, 16 insertions(+), 4 deletions(-)
+
+--- a/arch/blackfin/include/asm/page.h
++++ b/arch/blackfin/include/asm/page.h
+@@ -10,4 +10,9 @@
+ #include <asm-generic/page.h>
+ #define MAP_NR(addr) (((unsigned long)(addr)-PAGE_OFFSET) >> PAGE_SHIFT)
+ 
++#define VM_DATA_DEFAULT_FLAGS \
++	(VM_READ | VM_WRITE | \
++	((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \
++		 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
++
+ #endif
+--- a/arch/frv/include/asm/page.h
++++ b/arch/frv/include/asm/page.h
+@@ -63,12 +63,10 @@ extern unsigned long max_pfn;
+ #define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
+ 
+ 
+-#ifdef CONFIG_MMU
+ #define VM_DATA_DEFAULT_FLAGS \
+ 	(VM_READ | VM_WRITE | \
+ 	((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \
+ 		 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
+-#endif
+ 
+ #endif /* __ASSEMBLY__ */
+ 
+--- a/fs/binfmt_elf_fdpic.c
++++ b/fs/binfmt_elf_fdpic.c
+@@ -171,6 +171,9 @@ static int load_elf_fdpic_binary(struct 
+ #ifdef ELF_FDPIC_PLAT_INIT
+ 	unsigned long dynaddr;
+ #endif
++#ifndef CONFIG_MMU
++	unsigned long stack_prot;
++#endif
+ 	struct file *interpreter = NULL; /* to shut gcc up */
+ 	char *interpreter_name = NULL;
+ 	int executable_stack;
+@@ -316,6 +319,8 @@ static int load_elf_fdpic_binary(struct 
+ 	 * defunct, deceased, etc. after this point we have to exit via
+ 	 * error_kill */
+ 	set_personality(PER_LINUX_FDPIC);
++	if (elf_read_implies_exec(&exec_params.hdr, executable_stack))
++		current->personality |= READ_IMPLIES_EXEC;
+ 	set_binfmt(&elf_fdpic_format);
+ 
+ 	current->mm->start_code = 0;
+@@ -377,9 +382,13 @@ static int load_elf_fdpic_binary(struct 
+ 	if (stack_size < PAGE_SIZE * 2)
+ 		stack_size = PAGE_SIZE * 2;
+ 
++	stack_prot = PROT_READ | PROT_WRITE;
++	if (executable_stack == EXSTACK_ENABLE_X ||
++	    (executable_stack == EXSTACK_DEFAULT && VM_STACK_FLAGS & VM_EXEC))
++		stack_prot |= PROT_EXEC;
++
+ 	down_write(&current->mm->mmap_sem);
+-	current->mm->start_brk = do_mmap(NULL, 0, stack_size,
+-					 PROT_READ | PROT_WRITE | PROT_EXEC,
++	current->mm->start_brk = do_mmap(NULL, 0, stack_size, stack_prot,
+ 					 MAP_PRIVATE | MAP_ANONYMOUS | MAP_GROWSDOWN,
+ 					 0);
+ 
diff --git a/debian/patches/series/7 b/debian/patches/series/7
index a1aa2f6b7993..bc337f7732b8 100644
--- a/debian/patches/series/7
+++ b/debian/patches/series/7
@@ -1,2 +1,3 @@
 + bugfix/all/clocksource-events-Fix-fallout-of-generic-code-changes.patch
++ bugfix/all/fdpic-respect-pt_gnu_stack-exec-protection-markings-when-creating-nommu-stack.patch
 + bugfix/all/split-flush_old_exec-into-two-functions.patch