diff options
| author | Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> | 2006-05-01 23:16:04 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-05-02 05:17:45 +0400 |
| commit | 275e6e1ee2bafde77e9390b27e876fa83f24cb60 (patch) | |
| tree | fca0c0a7e3bdabe82bc75a0dad5c765f3b6edaf0 /arch/um | |
| parent | cb8aa3d29b562e4c16fdfa4ecc8170ddc55397f4 (diff) | |
| download | linux-275e6e1ee2bafde77e9390b27e876fa83f24cb60.tar.xz | |
[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 <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/um')
| -rw-r--r-- | arch/um/Makefile | 6 | ||||
| -rw-r--r-- | arch/um/kernel/skas/Makefile | 9 | ||||
| -rw-r--r-- | arch/um/sys-i386/Makefile | 2 | ||||
| -rw-r--r-- | arch/um/sys-x86_64/Makefile | 2 |
4 files changed, 17 insertions, 2 deletions
diff --git a/arch/um/Makefile b/arch/um/Makefile index 930e00612a22..bed604af6c6f 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -118,6 +118,10 @@ prepare: $(ARCH_DIR)/include/kern_constants.h LINK-$(CONFIG_LD_SCRIPT_STATIC) += -static LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib +CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,) \ + $(call cc-option, -fno-stack-protector,) \ + $(call cc-option, -fno-stack-protector-all,) + CPP_MODE-$(CONFIG_MODE_TT) := -DMODE_TT CONFIG_KERNEL_STACK_ORDER ?= 2 STACK_SIZE := $(shell echo $$[ 4096 * (1 << $(CONFIG_KERNEL_STACK_ORDER)) ] ) @@ -227,4 +231,4 @@ $(ARCH_DIR)/include/kern_constants.h: $(objtree)/$(ARCH_DIR)/include @echo ' SYMLINK $@' $(Q)ln -sf ../../../include/asm-um/asm-offsets.h $@ -export SUBARCH USER_CFLAGS OS +export SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING OS diff --git a/arch/um/kernel/skas/Makefile b/arch/um/kernel/skas/Makefile index 57181a920d48..ad842964707a 100644 --- a/arch/um/kernel/skas/Makefile +++ b/arch/um/kernel/skas/Makefile @@ -11,4 +11,11 @@ USER_OBJS := clone.o include arch/um/scripts/Makefile.rules # clone.o is in the stub, so it can't be built with profiling -$(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) diff --git a/arch/um/sys-i386/Makefile b/arch/um/sys-i386/Makefile index 82121ab03bb0..3734c3eb15a4 100644 --- a/arch/um/sys-i386/Makefile +++ b/arch/um/sys-i386/Makefile @@ -13,6 +13,8 @@ USER_OBJS := bugs.o ptrace_user.o sigcontext.o fault.o stub_segv.o USER_OBJS += user-offsets.s extra-y += user-offsets.s +CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING) + extra-$(CONFIG_MODE_TT) += unmap.o include arch/um/scripts/Makefile.rules diff --git a/arch/um/sys-x86_64/Makefile b/arch/um/sys-x86_64/Makefile index f739bea35195..6d3b29c74533 100644 --- a/arch/um/sys-x86_64/Makefile +++ b/arch/um/sys-x86_64/Makefile @@ -21,6 +21,8 @@ USER_OBJS := ptrace_user.o sigcontext.o stub_segv.o USER_OBJS += user-offsets.s extra-y += user-offsets.s +CFLAGS_stub_segv.o := $(CFLAGS_NO_HARDENING) + extra-$(CONFIG_MODE_TT) += unmap.o include arch/um/scripts/Makefile.rules |