Rob, On Mon, Nov 23, 2020 at 11:23:12AM +0100, Johan Hovold wrote: > Specify type alignment when declaring linker-section match-table entries > to prevent gcc from increasing alignment and corrupting the various > tables with padding (e.g. timers, irqchips, clocks, reserved memory). > > This is specifically needed on x86 where gcc (typically) aligns larger > objects like struct of_device_id with static extent on 32-byte > boundaries which at best prevents matching on anything but the first > entry. Specifying alignment when declaring variables suppresses this > optimisation. > > Here's a 64-bit example where all entries are corrupt as 16 bytes of > padding has been inserted before the first entry: > > ffffffff8266b4b0 D __clk_of_table > ffffffff8266b4c0 d __of_table_fixed_factor_clk > ffffffff8266b5a0 d __of_table_fixed_clk > ffffffff8266b680 d __clk_of_table_sentinel > > And here's a 32-bit example where the 8-byte-aligned table happens to be > placed on a 32-byte boundary so that all but the first entry are corrupt > due to the 28 bytes of padding inserted between entries: > > 812b3ec0 D __irqchip_of_table > 812b3ec0 d __of_table_irqchip1 > 812b3fa0 d __of_table_irqchip2 > 812b4080 d __of_table_irqchip3 > 812b4160 d irqchip_of_match_end > > Verified on x86 using gcc-9.3 and gcc-4.9 (which uses 64-byte > alignment), and on arm using gcc-7.2. > > Note that there are no in-tree users of these tables on x86 currently > (even if they are included in the image). > > Fixes: 54196ccbe0ba ("of: consolidate linker section OF match table declarations") > Fixes: f6e916b82022 ("irqchip: add basic infrastructure") > Cc: stable <stable@xxxxxxxxxxxxxxx> # 3.9 > Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> > --- Could you pick this one up for 5.11? Johan