From e8184e10f89736a23ea6eea8e24cd524c5c513d2 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 26 Jul 2013 00:08:25 +0200 Subject: [PATCH 1/2] m68k/atari: ARAnyM - Fix NatFeat module support 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 Signed-off-by: Geert Uytterhoeven Cc: stable@vger.kernel.org --- 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 2291a7d69d49..fa277aecfb78 100644 --- a/arch/m68k/emu/natfeat.c +++ b/arch/m68k/emu/natfeat.c @@ -18,9 +18,11 @@ #include #include +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]; From ea077b1b96e073eac5c3c5590529e964767fc5f7 Mon Sep 17 00:00:00 2001 From: Andreas Schwab Date: Fri, 9 Aug 2013 15:14:08 +0200 Subject: [PATCH 2/2] m68k: Truncate base in do_div() Explicitly truncate the second operand of do_div() to 32 bits to guard against bogus code calling it with a 64-bit divisor. [Thorsten] After upgrading from 3.2 to 3.10, mounting a btrfs volume fails with: btrfs: setting nodatacow, compression disabled btrfs: enabling auto recovery btrfs: disk space caching is enabled *** ZERO DIVIDE *** FORMAT=2 Current process id is 722 BAD KERNEL TRAP: 00000000 Modules linked in: evdev mac_hid ext4 crc16 jbd2 mbcache btrfs xor lzo_compress zlib_deflate raid6_pq crc32c libcrc32c PC: [<319535b2>] __btrfs_map_block+0x11c/0x119a [btrfs] SR: 2000 SP: 30c1fab4 a2: 30f0faf0 d0: 00000000 d1: 00001000 d2: 00000000 d3: 00000000 d4: 00010000 d5: 00000000 a0: 3085c72c a1: 3085c72c Process mount (pid: 722, task=30f0faf0) Frame format=2 instr addr=319535ae Stack from 30c1faec: 00000000 00000020 00000000 00001000 00000000 01401000 30253928 300ffc00 00a843ac 3026f640 00000000 00010000 0009e250 00d106c0 00011220 00000000 00001000 301c6830 0009e32a 000000ff 00000009 3085c72c 00000000 00000000 30c1fd14 00000000 00000020 00000000 30c1fd14 0009e26c 00000020 00000003 00000000 0009dd8a 300b0b6c 30253928 00a843ac 00001000 00000000 00000000 0000a008 3194e76a 30253928 00a843ac 00001000 00000000 00000000 00000002 Call Trace: [<00001000>] kernel_pg_dir+0x0/0x1000 [...] Code: 222e ff74 2a2e ff5c 2c2e ff60 4c45 1402 <2d40> ff64 2d41 ff68 2205 4c2e 1800 ff68 4c04 0800 2041 d1c0 2206 4c2e 1400 ff68 [Geert] As diagnosed by Andreas, fs/btrfs/volumes.c:__btrfs_map_block() calls do_div(stripe_nr, stripe_len); with stripe_len u64, while do_div() assumes the divisor is a 32-bit number. Due to the lack of truncation in the m68k-specific implementation of do_div(), the division is performed using the upper 32-bit word of stripe_len, which is zero. This was introduced by commit 53b381b3abeb86f12787a6c40fee9b2f71edc23b ("Btrfs: RAID5 and RAID6"), which changed the divisor from map->stripe_len (struct map_lookup.stripe_len is int) to a 64-bit temporary. Reported-by: Thorsten Glaser Signed-off-by: Andreas Schwab Tested-by: Thorsten Glaser Signed-off-by: Geert Uytterhoeven Cc: stable@vger.kernel.org --- arch/m68k/include/asm/div64.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/m68k/include/asm/div64.h b/arch/m68k/include/asm/div64.h index 444ea8a09e9f..ef881cfbbca9 100644 --- a/arch/m68k/include/asm/div64.h +++ b/arch/m68k/include/asm/div64.h @@ -15,16 +15,17 @@ unsigned long long n64; \ } __n; \ unsigned long __rem, __upper; \ + unsigned long __base = (base); \ \ __n.n64 = (n); \ if ((__upper = __n.n32[0])) { \ asm ("divul.l %2,%1:%0" \ - : "=d" (__n.n32[0]), "=d" (__upper) \ - : "d" (base), "0" (__n.n32[0])); \ + : "=d" (__n.n32[0]), "=d" (__upper) \ + : "d" (__base), "0" (__n.n32[0])); \ } \ asm ("divu.l %2,%1:%0" \ - : "=d" (__n.n32[1]), "=d" (__rem) \ - : "d" (base), "1" (__upper), "0" (__n.n32[1])); \ + : "=d" (__n.n32[1]), "=d" (__rem) \ + : "d" (__base), "1" (__upper), "0" (__n.n32[1])); \ (n) = __n.n64; \ __rem; \ })