On 12.12.2024 02:17, Andrew Cooper wrote: > On 12/12/2024 12:13 am, Volodymyr Babchuk wrote: >> Hello Jan, >> >> Jan Beulich <jbeul...@suse.com> writes: >> >>> On 11.12.2024 03:04, Volodymyr Babchuk wrote: >>>> Both GCC and Clang support -fstack-protector feature, which add stack >>>> canaries to functions where stack corruption is possible. This series >>>> makes possible to use this feature in Xen. I tested this on ARM64 and >>>> it is working as intended. Tested both with GCC and Clang. >>>> >>>> It is hard to enable this feature on x86, as GCC stores stack canary >>>> in %fs:40 by default, but Xen can't use %fs for various reasons. It is >>>> possibly to change stack canary location new newer GCC versions, but >>>> this will change minimal GCC requirement, which is also hard due to >>>> various reasons. So, this series focus mostly on ARM and RISCV. >>> Why exactly would it not be possible to offer the feature when new enough >>> gcc is in use? >> It is possible to use this feature with a modern enough GCC, yes. Are >> you suggesting to make HAS_STACK_PROTECTOR dependent on GCC_VERSION for >> x86 platform? > > (With the knowledge that this is a disputed Kconfig pattern, and will > need rebasing), the way I want this to work is simply: > > diff --git a/xen/Makefile b/xen/Makefile > index 0de0101fd0bf..5d0a88fb3c3f 100644 > --- a/xen/Makefile > +++ b/xen/Makefile > @@ -434,6 +434,9 @@ endif > > ifeq ($(CONFIG_STACK_PROTECTOR),y) > CFLAGS += -fstack-protector > +ifeq ($(CONFIG_X86),y) > +CFLAGS += -mstack-protector-guard=global > +endif > else > CFLAGS += -fno-stack-protector > endif > diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig > index 9cdd04721afa..7951ca908b36 100644 > --- a/xen/arch/x86/Kconfig > +++ b/xen/arch/x86/Kconfig > @@ -28,6 +28,7 @@ config X86 > select HAS_PCI_MSI > select HAS_PIRQ > select HAS_SCHED_GRANULARITY > + select HAS_STACK_PROTECTOR if > $(cc-option,-mstack-protector-guard=global) > select HAS_UBSAN > select HAS_VMAP > select HAS_VPCI if HVM > > > > Sadly, it doesn't build. I get a handful of: > > prelink.o: in function `cmdline_parse': > /home/andrew/xen.git/xen/common/kernel.c:216:(.init.text+0x20f2): failed > to convert GOTPCREL relocation against '__stack_chk_guard'; relink with > --no-relax > /home/andrew/xen.git/xen/common/kernel.c:230:(.init.text+0x246f): failed > to convert GOTPCREL relocation against '__stack_chk_guard'; relink with > --no-relax > > which is more toolchain-whispering than I feel like doing tonight.
For reference: https://sourceware.org/pipermail/binutils/2025-January/138631.html You didn't enter a gcc bug report yet, did you? Jan
