On Tue, Jan 10, 2017 at 10:33:40PM +0800, Herbert Xu wrote: > I recently applied the patch > > https://patchwork.kernel.org/patch/9468391/ > > and ended up with a boot crash when it tried to run the x86 chacha20 > code. It turned out that the patch changed a manually aligned > stack buffer to one that is aligned by gcc. What was happening was > that gcc can stack align to any value on x86-64 except 16. The > reason is that gcc assumes that the stack is always 16-byte aligned, > which is not actually the case in the kernel. BTW this is with Debian gcc 4.7.2 which does not allow an 8-byte stack alignment as attempted by the Makefile: $ gcc -S -O2 -mno-sse -mpreferred-stack-boundary=3 a.c a.c:1:0: error: -mpreferred-stack-boundary=3 is not between 4 and 12 $ Obviously this is not an issue if your compiler actually allows the 8-byte alignment. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
