On 24 July 2018 at 10:32, Matt Hart matthew.hart@linaro.org wrote:
On 24 July 2018 at 10:16, Will Deacon will.deacon@arm.com wrote:
On Mon, Jul 23, 2018 at 07:11:50PM +0100, Mark Brown wrote:
On Mon, Jul 23, 2018 at 05:59:12PM +0100, Build bot for Mark Brown wrote:
Today's -next fails to build an arm64 allmodconfig with:
arm64-allmodconfigERROR: "__sync_icache_dcache" [drivers/xen/xen-privcmd.ko] undefined!
using
aarch64-linux-gnu-gcc (Linaro GCC 5.3-2016.05) 5.3.1 20160412
however it builds perfectly fine with
aarch64-linux-gnu-gcc (Linaro GCC 6.2-2016.11) 6.2.1 20161016
which honestly seems like a sensible and worthwhile upgrade at this point anyway given that it's a year and a half old so I'm going to do that for my builder (perhaps even jump on a newer version) but it seemed worth highlighting in case this is considered undesirable. A similar issue is hitting on KernelCI, we should probably look at upgrading the toolchain there too.
Hmm, it looks to me like this comes about because xen/privcmd.c is being built as a module, but contains a call to set_pte_at() with a special pte:
pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot)); set_pte_at(r->mm, addr, ptep, pte);which on arm64 contains:
if (pte_present(pte) && pte_user_exec(pte) && !pte_special(pte)) __sync_icache_dcache(pte);so GCC 6 can optimise away the call to the non-exported symbol, but GCC 5 has trouble.
What I don't understand is why this suddenly cropped up. Did GCC 5 build linux-next arm64 allmodconfig last week?
KernelCI uses GCC5 for ARM64 and xen-privcmd.ko has been broken in linux-next (and mainline) allmodconfig for a long time
Bloody gmail and it's HTML mean't this didn't get delivered to linux-arm-kernel list. Resent.
Cheers,
Will