Le 07/02/2022 à 21:40, Andrew Morton a écrit : > On Mon, 7 Feb 2022 11:55:18 +0100 Christophe Leroy <christophe.leroy@xxxxxxxxxx> wrote: > >> While building a small config with CONFIG_CC_OPTIMISE_FOR_SIZE, >> I ended up with more than 50 times the following function in vmlinux: >> >> c00243bc <copy_overflow>: >> c00243bc: 94 21 ff f0 stwu r1,-16(r1) >> c00243c0: 7c 85 23 78 mr r5,r4 >> c00243c4: 7c 64 1b 78 mr r4,r3 >> c00243c8: 3c 60 c0 62 lis r3,-16286 >> c00243cc: 7c 08 02 a6 mflr r0 >> c00243d0: 38 63 5e e5 addi r3,r3,24293 >> c00243d4: 90 01 00 14 stw r0,20(r1) >> c00243d8: 4b ff 82 45 bl c001c61c <__warn_printk> >> c00243dc: 0f e0 00 00 twui r0,0 >> c00243e0: 80 01 00 14 lwz r0,20(r1) >> c00243e4: 38 21 00 10 addi r1,r1,16 >> c00243e8: 7c 08 03 a6 mtlr r0 >> c00243ec: 4e 80 00 20 blr >> >> That function being a non conditional warning on an error path, >> it is not worth inlining. >> >> Outline it. > > "uninline" is the conventional term for this. > >> This reduces the size of vmlinux by almost 4kbytes. > > Did you consider uninlining check_copy_size() instead? > If you uninline check_copy_size() you loose the benefit of constant folding and build time overflow detection for constant sizes, and I'm not sure __builtin_object_size() works at all if uninlined. Christophe
