From: Julien Grall Date: Tue, 2 Feb 2021 10:35:42 +0000 (+0100) Subject: memory: fix build with COVERAGE but !HVM X-Git-Tag: archive/raspbian/4.16.0+51-g0941d6cb-1+rpi1~2^2~42^2~956 X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=119c98972c4e737508df827bbbc8453cc93292c7;p=xen.git memory: fix build with COVERAGE but !HVM Xen is heavily relying on the DCE stage to remove unused code so the linker doesn't throw an error because a function is not implemented yet we defined a prototype for it. On some GCC versions (such as 9.4 provided by Debian sid), the compiler DCE stage will not manage to figure that out for xenmem_add_to_physmap_batch(): ld: ld: prelink.o: in function `xenmem_add_to_physmap_batch': /xen/xen/common/memory.c:942: undefined reference to `xenmem_add_to_physmap_one' /xen/xen/common/memory.c:942:(.text+0x22145): relocation truncated to fit: R_X86_64_PLT32 against undefined symbol `xenmem_add_to_physmap_one' prelink-efi.o: in function `xenmem_add_to_physmap_batch': /xen/xen/common/memory.c:942: undefined reference to `xenmem_add_to_physmap_one' make[2]: *** [Makefile:215: /root/xen/xen/xen.efi] Error 1 make[2]: *** Waiting for unfinished jobs.... ld: /xen/xen/.xen-syms.0: hidden symbol `xenmem_add_to_physmap_one' isn't defined ld: final link failed: bad value It is not entirely clear why the compiler DCE is not detecting the unused code. However, cloning the check introduced by the commit below into xenmem_add_to_physmap_batch() does the trick. No functional change intended. Fixes: d4f699a0df6c ("x86/mm: p2m_add_foreign() is HVM-only") Reported-by: Oleksandr Tyshchenko Signed-off-by: Julien Grall Signed-off-by: Jan Beulich Acked-by: Andrew Cooper Reviewed-by: Wei Liu Release-Acked-by: Ian Jackson --- diff --git a/xen/common/memory.c b/xen/common/memory.c index 01cab7e493..f23b001fd2 100644 --- a/xen/common/memory.c +++ b/xen/common/memory.c @@ -904,6 +904,17 @@ static int xenmem_add_to_physmap_batch(struct domain *d, { union add_to_physmap_extra extra = {}; + /* + * In some configurations, (!HVM, COVERAGE), the xenmem_add_to_physmap_one() + * call doesn't succumb to dead-code-elimination. Duplicate the short-circut + * from xatp_permission_check() to try and help the compiler out. + */ + if ( !paging_mode_translate(d) ) + { + ASSERT_UNREACHABLE(); + return -EACCES; + } + if ( unlikely(xatpb->size < extent) ) return -EILSEQ;