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@debian.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 19 insertions, 4 deletions

diff --git a/arch/m68k/emu/natfeat.c b/arch/m68k/emu/natfeat.c
index 2291a7d69d49..fa277aecfb78 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];