Hi, I came across a problem concerning structure alignment on ARM architectures (in this case the "clock_provider" struct) when structures are placed by means of the "section" compiler attribute. I noticed that with a certain cross compiler one byte padding is inserted in between the structures:
<snip> System.map c074cec0 T __clk_of_table c074cec0 t __of_table_fixed_factor_clk c074cec0 T __stop_kprobe_blacklist c074cf88 t __of_table_fixed_clk c074d050 t __of_table_gpio_gate_clk c074d118 t __of_table_mv88f6180_clk c074d1e0 t __of_table_kirkwood_clk c074d2a8 t __clk_of_table_sentinel <snap> As one can see the difference between the adresses are 200 bytes although a clock_provider only is 196 bytes in size. The problem is that in of_clk_init() the __clk_of_table is used as the base of an array. Due to the padding the values in all array elements but the first one are corruped. However with another cross compiler I could not trigger this. So this issue seems to be compiler/linker dependent. With the attached patch applied the layout is correct: c074ce58 T __clk_of_table c074ce58 t __of_table_fixed_factor_clk c074ce58 T __stop_kprobe_blacklist c074cf1c t __of_table_fixed_clk c074cfe0 t __of_table_gpio_gate_clk c074d0a4 t __of_table_mv88f6180_clk c074d168 t __of_table_kirkwood_clk c074d22c t __clk_of_table_sentinel I can trigger the issue with this compiler: wget http://www.plugcomputer.org/405/us/gplugd/tool-chain/arm-marvell-linux-gnueabi.tar.bz2 Note that this issue popped up some years ago for x86 too: http://lkml.iu.edu/hypermail/linux/kernel/0706.2/2552.html I am not sure that this is the right fix though, thats why I sent that as an RFC. Regards, Lino Lino Sanfilippo (1): ARM: Ensure correct structure alignment when using compiler attribute "section" include/linux/compiler.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
