[PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[Petri Gynther]

$ iwconfig mlan0 essid MySSID
[   36.930000] Path: /sbin/iwconfig
[   36.930000] CPU: 0 PID: 203 Comm: iwconfig Not tainted 4.7.0 #2
[   36.940000] task: 866f83a0 ti: 866a6000 task.ti: 866a6000
[   36.940000]
[ECR   ]: 0x00230400 => Misaligned r/w from 0x8677f403
[   36.960000] [EFA   ]: 0x8677f403
[   36.960000] [BLINK ]: mwifiex_scan_networks+0x17a/0x198c [mwifiex]
[   36.960000] [ERET  ]: mwifiex_scan_networks+0x18a/0x198c [mwifiex]
[   36.980000] [STAT32]: 0x00000206 : K         E2 E1
[   36.980000] BTA: 0x700736e2   SP: 0x866a7d0c  FP: 0x5faddc84
[   37.000000] LPS: 0x806a37ec  LPE: 0x806a37fa LPC: 0x00000000
[   37.000000] r00: 0x8677f401  r01: 0x8668aa08 r02: 0x00000001
r03: 0x00000000 r04: 0x8668b600 r05: 0x8677f406
r06: 0x8702b600 r07: 0x00000000 r08: 0x8702b600
r09: 0x00000000 r10: 0x870b3b00 r11: 0x00000000
r12: 0x00000000
[   37.040000]
[   37.040000] Stack Trace:
[   37.040000]   mwifiex_scan_networks+0x18a/0x198c [mwifiex]

Root cause:
mwifiex driver calls is_zero_ether_addr() against byte-aligned address:

drivers/net/wireless/marvell/mwifiex/fw.h:
struct mwifiex_scan_cmd_config {
        /*
         *  BSS mode to be sent in the firmware command
         */
        u8 bss_mode;

        /* Specific BSSID used to filter scan results in the firmware */
        u8 specific_bssid[ETH_ALEN];

        ...
} __packed;

drivers/net/wireless/marvell/mwifiex/scan.c:
mwifiex_config_scan(..., struct mwifiex_scan_cmd_config *scan_cfg_out, ...)
        ...
        if (adapter->ext_scan &&
            !is_zero_ether_addr(scan_cfg_out->specific_bssid)) {
            ...
        }

Since firmware-related struct mwifiex_scan_cmd_config cannot be changed,
modify is_zero_ether_addr() to handle byte-aligned addresses.

Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Joe Perches <joe@perches.com>
Cc: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Petri Gynther <pgynther@google.com>
---
 include/linux/etherdevice.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 37ff4a6..0cfd243 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -90,11 +90,13 @@ static inline bool is_link_local_ether_addr(const u8 *addr)
  * @addr: Pointer to a six-byte array containing the Ethernet address
  *
  * Return true if the address is all zeroes.
- *
- * Please note: addr must be aligned to u16.
  */
 static inline bool is_zero_ether_addr(const u8 *addr)
 {
+	if ((u32)addr & 0x1)
+		return (addr[0] | addr[1] | addr[2] | addr[3] | addr[4] |
+			addr[5]) == 0;
+
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 	return ((*(const u32 *)addr) | (*(const u16 *)(addr + 4))) == 0;
 #else
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[Joe Perches]

On Fri, 2016-08-12 at 17:15 -0700, Petri Gynther wrote:
> $ iwconfig mlan0 essid MySSID
> [   36.930000] Path: /sbin/iwconfig
> [   36.930000] CPU: 0 PID: 203 Comm: iwconfig Not tainted 4.7.0 #2
> [   36.940000] task: 866f83a0 ti: 866a6000 task.ti: 866a6000
> [   36.940000]
> [ECR   ]: 0x00230400 => Misaligned r/w from 0x8677f403
> [   36.960000] [EFA   ]: 0x8677f403
> [   36.960000] [BLINK ]: mwifiex_scan_networks+0x17a/0x198c [mwifiex]
> [   36.960000] [ERET  ]: mwifiex_scan_networks+0x18a/0x198c [mwifiex]
> [   36.980000] [STAT32]: 0x00000206 : K         E2 E1
> [   36.980000] BTA: 0x700736e2   SP: 0x866a7d0c  FP: 0x5faddc84
> [   37.000000] LPS: 0x806a37ec  LPE: 0x806a37fa LPC: 0x00000000
> [   37.000000] r00: 0x8677f401  r01: 0x8668aa08 r02: 0x00000001
> r03: 0x00000000 r04: 0x8668b600 r05: 0x8677f406
> r06: 0x8702b600 r07: 0x00000000 r08: 0x8702b600
> r09: 0x00000000 r10: 0x870b3b00 r11: 0x00000000
> r12: 0x00000000
> [   37.040000]
> [   37.040000] Stack Trace:
> [   37.040000]   mwifiex_scan_networks+0x18a/0x198c [mwifiex]
> 
> Root cause:
> mwifiex driver calls is_zero_ether_addr() against byte-aligned address:
> 
> drivers/net/wireless/marvell/mwifiex/fw.h:
> struct mwifiex_scan_cmd_config {
>         /*
>          *  BSS mode to be sent in the firmware command
>          */
>         u8 bss_mode;
> 
>         /* Specific BSSID used to filter scan results in the firmware */
>         u8 specific_bssid[ETH_ALEN];
> 
>         ...
> } __packed;
> 
> drivers/net/wireless/marvell/mwifiex/scan.c:
> mwifiex_config_scan(..., struct mwifiex_scan_cmd_config *scan_cfg_out, ...)
>         ...
>         if (adapter->ext_scan &&
>             !is_zero_ether_addr(scan_cfg_out->specific_bssid)) {
>             ...
>         }
> 
> Since firmware-related struct mwifiex_scan_cmd_config cannot be changed,
> modify is_zero_ether_addr() to handle byte-aligned addresses.

Or add is_zero_ether_addr_unaligned and use it here.

> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Joe Perches <joe@perches.com>
> Cc: Amitkumar Karwar <akarwar@marvell.com>
> Signed-off-by: Petri Gynther <pgynther@google.com>
> ---
>  include/linux/etherdevice.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
> index 37ff4a6..0cfd243 100644
> --- a/include/linux/etherdevice.h
> +++ b/include/linux/etherdevice.h
> @@ -90,11 +90,13 @@ static inline bool is_link_local_ether_addr(const u8 *addr)
>   * @addr: Pointer to a six-byte array containing the Ethernet address
>   *
>   * Return true if the address is all zeroes.
> - *
> - * Please note: addr must be aligned to u16.
>   */
>  static inline bool is_zero_ether_addr(const u8 *addr)
>  {
> +	if ((u32)addr & 0x1)
> +		return (addr[0] | addr[1] | addr[2] | addr[3] | addr[4] |
> +			addr[5]) == 0;
> +

So why skip the CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
optimization below?

>  #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
>  	return ((*(const u32 *)addr) | (*(const u16 *)(addr + 4))) == 0;
>  #else

How about adding:

static inline bool is_zero_ether_addr_unaligned(const u8 *addr)
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
	return is_zero_ether_addr(addr);
#else
	return addr[0] | addr[1] | addr[2] | addr[3] | addr[4] | addr[5];
#endif
}

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[Petri Gynther]

Hi Joe,

On Fri, Aug 12, 2016 at 5:28 PM, Joe Perches <joe@perches.com> wrote:
> On Fri, 2016-08-12 at 17:15 -0700, Petri Gynther wrote:
>> $ iwconfig mlan0 essid MySSID
>> [   36.930000] Path: /sbin/iwconfig
>> [   36.930000] CPU: 0 PID: 203 Comm: iwconfig Not tainted 4.7.0 #2
>> [   36.940000] task: 866f83a0 ti: 866a6000 task.ti: 866a6000
>> [   36.940000]
>> [ECR   ]: 0x00230400 => Misaligned r/w from 0x8677f403
>> [   36.960000] [EFA   ]: 0x8677f403
>> [   36.960000] [BLINK ]: mwifiex_scan_networks+0x17a/0x198c [mwifiex]
>> [   36.960000] [ERET  ]: mwifiex_scan_networks+0x18a/0x198c [mwifiex]
>> [   36.980000] [STAT32]: 0x00000206 : K         E2 E1
>> [   36.980000] BTA: 0x700736e2   SP: 0x866a7d0c  FP: 0x5faddc84
>> [   37.000000] LPS: 0x806a37ec  LPE: 0x806a37fa LPC: 0x00000000
>> [   37.000000] r00: 0x8677f401  r01: 0x8668aa08 r02: 0x00000001
>> r03: 0x00000000 r04: 0x8668b600 r05: 0x8677f406
>> r06: 0x8702b600 r07: 0x00000000 r08: 0x8702b600
>> r09: 0x00000000 r10: 0x870b3b00 r11: 0x00000000
>> r12: 0x00000000
>> [   37.040000]
>> [   37.040000] Stack Trace:
>> [   37.040000]   mwifiex_scan_networks+0x18a/0x198c [mwifiex]
>>
>> Root cause:
>> mwifiex driver calls is_zero_ether_addr() against byte-aligned address:
>>
>> drivers/net/wireless/marvell/mwifiex/fw.h:
>> struct mwifiex_scan_cmd_config {
>>         /*
>>          *  BSS mode to be sent in the firmware command
>>          */
>>         u8 bss_mode;
>>
>>         /* Specific BSSID used to filter scan results in the firmware */
>>         u8 specific_bssid[ETH_ALEN];
>>
>>         ...
>> } __packed;
>>
>> drivers/net/wireless/marvell/mwifiex/scan.c:
>> mwifiex_config_scan(..., struct mwifiex_scan_cmd_config *scan_cfg_out, ...)
>>         ...
>>         if (adapter->ext_scan &&
>>             !is_zero_ether_addr(scan_cfg_out->specific_bssid)) {
>>             ...
>>         }
>>
>> Since firmware-related struct mwifiex_scan_cmd_config cannot be changed,
>> modify is_zero_ether_addr() to handle byte-aligned addresses.
>
> Or add is_zero_ether_addr_unaligned and use it here.
>
>> Cc: Kalle Valo <kvalo@codeaurora.org>
>> Cc: David S. Miller <davem@davemloft.net>
>> Cc: Joe Perches <joe@perches.com>
>> Cc: Amitkumar Karwar <akarwar@marvell.com>
>> Signed-off-by: Petri Gynther <pgynther@google.com>
>> ---
>>  include/linux/etherdevice.h | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
>> index 37ff4a6..0cfd243 100644
>> --- a/include/linux/etherdevice.h
>> +++ b/include/linux/etherdevice.h
>> @@ -90,11 +90,13 @@ static inline bool is_link_local_ether_addr(const u8 *addr)
>>   * @addr: Pointer to a six-byte array containing the Ethernet address
>>   *
>>   * Return true if the address is all zeroes.
>> - *
>> - * Please note: addr must be aligned to u16.
>>   */
>>  static inline bool is_zero_ether_addr(const u8 *addr)
>>  {
>> +     if ((u32)addr & 0x1)
>> +             return (addr[0] | addr[1] | addr[2] | addr[3] | addr[4] |
>> +                     addr[5]) == 0;
>> +
>
> So why skip the CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> optimization below?
>
>>  #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
>>       return ((*(const u32 *)addr) | (*(const u16 *)(addr + 4))) == 0;
>>  #else
>
> How about adding:
>
> static inline bool is_zero_ether_addr_unaligned(const u8 *addr)
> {
> #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
>         return is_zero_ether_addr(addr);
> #else
>         return addr[0] | addr[1] | addr[2] | addr[3] | addr[4] | addr[5];
> #endif
> }
>

I like your idea. I'll add is_zero_ether_addr_unaligned() and use it
in mwifiex driver.

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 3383 bytes --]

Hi Petri,

[auto build test WARNING on net-next/master]
[also build test WARNING on v4.8-rc1 next-20160812]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Petri-Gynther/Modify-is_zero_ether_addr-to-handle-byte-aligned-addresses/20160813-081835
config: x86_64-randconfig-n0-08130925 (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   In file included from include/asm-generic/bug.h:4:0,
                    from arch/x86/include/asm/bug.h:35,
                    from include/linux/bug.h:4,
                    from include/linux/mmdebug.h:4,
                    from include/linux/gfp.h:4,
                    from net/llc/llc_if.c:14:
   include/linux/etherdevice.h: In function 'is_zero_ether_addr':
   include/linux/etherdevice.h:96:6: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
     if ((u32)addr & 0x1)
         ^
   include/linux/compiler.h:149:30: note: in definition of macro '__trace_if'
     if (__builtin_constant_p(!!(cond)) ? !!(cond) :   \
                                 ^~~~
>> include/linux/etherdevice.h:96:2: note: in expansion of macro 'if'
     if ((u32)addr & 0x1)
     ^~
   include/linux/etherdevice.h:96:6: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
     if ((u32)addr & 0x1)
         ^
   include/linux/compiler.h:149:42: note: in definition of macro '__trace_if'
     if (__builtin_constant_p(!!(cond)) ? !!(cond) :   \
                                             ^~~~
>> include/linux/etherdevice.h:96:2: note: in expansion of macro 'if'
     if ((u32)addr & 0x1)
     ^~
   include/linux/etherdevice.h:96:6: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
     if ((u32)addr & 0x1)
         ^
   include/linux/compiler.h:160:16: note: in definition of macro '__trace_if'
      ______r = !!(cond);     \
                   ^~~~
>> include/linux/etherdevice.h:96:2: note: in expansion of macro 'if'
     if ((u32)addr & 0x1)
     ^~

vim +/if +96 include/linux/etherdevice.h

    80	#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
    81		return (((*(const u32 *)addr) ^ (*(const u32 *)b)) |
    82			(__force int)((a[2] ^ b[2]) & m)) == 0;
    83	#else
    84		return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
    85	#endif
    86	}
    87	
    88	/**
    89	 * is_zero_ether_addr - Determine if give Ethernet address is all zeros.
    90	 * @addr: Pointer to a six-byte array containing the Ethernet address
    91	 *
    92	 * Return true if the address is all zeroes.
    93	 */
    94	static inline bool is_zero_ether_addr(const u8 *addr)
    95	{
  > 96		if ((u32)addr & 0x1)
    97			return (addr[0] | addr[1] | addr[2] | addr[3] | addr[4] |
    98				addr[5]) == 0;
    99	
   100	#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
   101		return ((*(const u32 *)addr) | (*(const u16 *)(addr + 4))) == 0;
   102	#else
   103		return (*(const u16 *)(addr + 0) |
   104			*(const u16 *)(addr + 2) |

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 25700 bytes --]

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1628 bytes --]

Hi Petri,

[auto build test ERROR on net-next/master]
[also build test ERROR on v4.8-rc1 next-20160812]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Petri-Gynther/Modify-is_zero_ether_addr-to-handle-byte-aligned-addresses/20160813-081835
config: powerpc-defconfig (attached as .config)
compiler: powerpc64-linux-gnu-gcc (Debian 5.4.0-6) 5.4.0 20160609
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=powerpc 

All errors (new ones prefixed by >>):

   In file included from arch/powerpc/kernel/prom_parse.c:6:0:
   include/linux/etherdevice.h: In function 'is_zero_ether_addr':
>> include/linux/etherdevice.h:96:6: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
     if ((u32)addr & 0x1)
         ^
   cc1: all warnings being treated as errors

vim +96 include/linux/etherdevice.h

    90	 * @addr: Pointer to a six-byte array containing the Ethernet address
    91	 *
    92	 * Return true if the address is all zeroes.
    93	 */
    94	static inline bool is_zero_ether_addr(const u8 *addr)
    95	{
  > 96		if ((u32)addr & 0x1)
    97			return (addr[0] | addr[1] | addr[2] | addr[3] | addr[4] |
    98				addr[5]) == 0;
    99	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 22404 bytes --]

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[David Miller]

From: Petri Gynther <pgynther@google.com>
Date: Fri, 12 Aug 2016 17:15:30 -0700

> Root cause:
> mwifiex driver calls is_zero_ether_addr() against byte-aligned address:

MAC addresses really must be 16-bit aligned to be used with any of the
ethernet address manipulation and test interfaces.

Therefore this driver should do whatever it takes to avoid passing
a byte-aligned MAC address anywhere.

We _SHOULD NOT_ add support for byte aligned addresses to these
interfaces, nor add routines which by-name can handle them.

Fix this driver instead of polluting out common interfaces
unnecessarily.

Thanks.

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[Petri Gynther]

On Fri, Aug 12, 2016 at 8:26 PM, David Miller <davem@davemloft.net> wrote:
> From: Petri Gynther <pgynther@google.com>
> Date: Fri, 12 Aug 2016 17:15:30 -0700
>
>> Root cause:
>> mwifiex driver calls is_zero_ether_addr() against byte-aligned address:
>
> MAC addresses really must be 16-bit aligned to be used with any of the
> ethernet address manipulation and test interfaces.
>
> Therefore this driver should do whatever it takes to avoid passing
> a byte-aligned MAC address anywhere.
>
> We _SHOULD NOT_ add support for byte aligned addresses to these
> interfaces, nor add routines which by-name can handle them.
>

ether_addr_equal_unaligned() exists.

commit 73eaef87e98a96fe8b8a586f916b2721bf512efa
Author: Joe Perches <joe@perches.com>
Date:   Fri Dec 6 14:21:01 2013 -0800

    etherdevice: Add ether_addr_equal_unaligned

    Add a generic routine to test if possibly unaligned
    to u16 Ethernet addresses are equal.

    If CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is set,
    this uses the slightly faster generic routine
    ether_addr_equal, otherwise this uses memcmp.

    Signed-off-by: Joe Perches <joe@perches.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>

> Fix this driver instead of polluting out common interfaces
> unnecessarily.
>

Amitkumar -- is this fixable in mwifiex driver and firmware? It looks
like your firmware expects u8 specific_bssid[ETH_ALEN] at byte offset
1, per struct mwifiex_scan_cmd_config definition.

I'll let Marvell take it from here.

> Thanks.

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[Joe Perches]

On Fri, 2016-08-12 at 20:26 -0700, David Miller wrote:
> From: Petri Gynther <pgynther@google.com>
> Date: Fri, 12 Aug 2016 17:15:30 -0700
> 
> > Root cause:
> > mwifiex driver calls is_zero_ether_addr() against byte-aligned address:
> 
> MAC addresses really must be 16-bit aligned to be used with any of the
> ethernet address manipulation and test interfaces.
> 
> Therefore this driver should do whatever it takes to avoid passing
> a byte-aligned MAC address anywhere.
> 
> We _SHOULD NOT_ add support for byte aligned addresses to these
> interfaces, nor add routines which by-name can handle them.

My recollection is that batman uses unaligned addresses
and some form of _unaligned tests are required there.

It seems that other wireless drivers also use _unaligned
in various forms.

> Fix this driver instead of polluting out common interfaces
> unnecessarily.

One solution might be to copy a hardware interface structure
to another struct with appropriate alignment.

Re: [PATCH] Modify is_zero_ether_addr() to handle byte-aligned addresses

[David Miller]

From: Joe Perches <joe@perches.com>
Date: Fri, 12 Aug 2016 21:00:27 -0700

> One solution might be to copy a hardware interface structure
> to another struct with appropriate alignment.

Right, especially if this is a slow path that would be an appropriate
way to handle this.