[ 3.8.y.z extended stable ] Patch "m68k/atari: ARAnyM - Fix NatFeat module support" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    m68k/atari: ARAnyM - Fix NatFeat module support

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 355edc335b1ceb2e805c0a100780cf2a832e43ab Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert at linux-m68k.org>
Date: Fri, 26 Jul 2013 00:08:25 +0200
Subject: m68k/atari: ARAnyM - Fix NatFeat module support

commit e8184e10f89736a23ea6eea8e24cd524c5c513d2 upstream.

As pointed out by Andreas Schwab, pointers passed to ARAnyM NatFeat calls
should be physical addresses, not virtual addresses.

Fortunately on Atari, physical and virtual kernel addresses are the same,
as long as normal kernel memory is concerned, so this usually worked fine
without conversion.

But for modules, pointers to literal strings are located in vmalloc()ed
memory. Depending on the version of ARAnyM, this causes the nf_get_id()
call to just fail, or worse, crash ARAnyM itself with e.g.

    Gotcha! Illegal memory access. Atari PC = $968c

This is a big issue for distro kernels, who want to have all drivers as
loadable modules in an initrd.

Add a wrapper for nf_get_id() that copies the literal to the stack to
work around this issue.

Reported-by: Thorsten Glaser <tg at debian.org>
Signed-off-by: Geert Uytterhoeven <geert at linux-m68k.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/m68k/emu/natfeat.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/arch/m68k/emu/natfeat.c b/arch/m68k/emu/natfeat.c
index 2291a7d..fa277ae 100644
--- a/arch/m68k/emu/natfeat.c
+++ b/arch/m68k/emu/natfeat.c
@@ -18,9 +18,11 @@
 #include <asm/machdep.h>
 #include <asm/natfeat.h>

+extern long nf_get_id2(const char *feature_name);
+
 asm("\n"
-"	.global nf_get_id,nf_call\n"
-"nf_get_id:\n"
+"	.global nf_get_id2,nf_call\n"
+"nf_get_id2:\n"
 "	.short	0x7300\n"
 "	rts\n"
 "nf_call:\n"
@@ -29,12 +31,25 @@ asm("\n"
 "1:	moveq.l	#0,%d0\n"
 "	rts\n"
 "	.section __ex_table,\"a\"\n"
-"	.long	nf_get_id,1b\n"
+"	.long	nf_get_id2,1b\n"
 "	.long	nf_call,1b\n"
 "	.previous");
-EXPORT_SYMBOL_GPL(nf_get_id);
 EXPORT_SYMBOL_GPL(nf_call);

+long nf_get_id(const char *feature_name)
+{
+	/* feature_name may be in vmalloc()ed memory, so make a copy */
+	char name_copy[32];
+	size_t n;
+
+	n = strlcpy(name_copy, feature_name, sizeof(name_copy));
+	if (n >= sizeof(name_copy))
+		return 0;
+
+	return nf_get_id2(name_copy);
+}
+EXPORT_SYMBOL_GPL(nf_get_id);
+
 void nfprint(const char *fmt, ...)
 {
 	static char buf[256];
--
1.8.1.2