From 275e6e1ee2bafde77e9390b27e876fa83f24cb60 Mon Sep 17 00:00:00 2001 From: Paolo 'Blaisorblade' Giarrusso Date: Mon, 1 May 2006 12:16:04 -0700 Subject: [PATCH] uml: fix compilation and execution with hardened GCC To make some half-assembly stubs compile, disable various "hardened" GCC features: *) we can't make it build PIC code as we need %ebx to do syscalls and GCC wants it free for PIC *) we can't leave stack protection as the stub is moved (not relocated!) in memory so the RIP-relative access to the canary tries reading from an unmapped address and causes a segfault, since we move the stub of various megabytes (the exact amount will be decided at runtime) away from the link-time address. Signed-off-by: Paolo 'Blaisorblade' Giarrusso Acked-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/skas/Makefile | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'arch/um/kernel') diff --git a/arch/um/kernel/skas/Makefile b/arch/um/kernel/skas/Makefile index 57181a920d48..ad842964707a 100644 --- a/arch/um/kernel/skas/Makefile +++ b/arch/um/kernel/skas/Makefile @@ -11,4 +11,11 @@ USER_OBJS := clone.o include arch/um/scripts/Makefile.rules # clone.o is in the stub, so it can't be built with profiling -$(obj)/clone.o : c_flags = -Wp,-MD,$(depfile) $(call unprofile,$(USER_CFLAGS)) +# GCC hardened also auto-enables -fpic, but we need %ebx so it can't work -> +# disable it + +CFLAGS_clone.o := $(CFLAGS_NO_HARDENING) + +# since we're setting c_flags we _must_ add $(CFLAGS_$(*F).o). + +$(obj)/clone.o : c_flags = -Wp,-MD,$(depfile) $(call unprofile,$(USER_CFLAGS)) $(CFLAGS_$(*F).o) -- cgit v1.2.3-59-g8ed1b