If we get an exception during early boot, walk the exception table to
see if we should intercept it. The main use case for this is to allow
rdmsr_safe()/wrmsr_safe() during CPU initialization.
Since the exception table is currently sorted at runtime, and fairly
late in startup, this code walks the exception table linearly. We
obviously don't need to worry about modules, however: none have been
loaded at this point.
[ v2: Use early_fixup_exception() instead of linear search ]
Link: http://lkml.kernel.org/r/1334794610-5546-5-git-send-email-hpa@zytor.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
While testing the patchset at
http://lkml.kernel.org/r/1306873314-32523-1-git-send-email-bp@alien8.de
with binutils 2.16.1 from hell, kernel build fails with the following
error:
arch/x86/ia32/ia32entry.S: Assembler messages:
arch/x86/ia32/ia32entry.S:139: Error: too many positional arguments
make[2]: *** [arch/x86/ia32/ia32entry.o] Error 1
make[1]: *** [arch/x86/ia32] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [arch/x86] Error 2
make: *** Waiting for unfinished jobs....
due to spaces between the operators of the __USER32_CS define. Fix it so
that gas 2.16 can swallow it too.
Signed-off-by: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/1307131642-32595-1-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Make the GDT_ENTRY() macro in <asm/segment.h> safe for use in
assembly code by guarding the ULL suffixes with _AC() macros.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4D5DFBE4.7090104@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
gas prior to (perhaps) 2.16.90 has problems with passing non-
parenthesized expressions containing spaces to macros. Spaces, however,
get inserted by cpp between any macro expanding to a number and a
subsequent + or -. For the +, current x86 gas then removes the space
again (future gas may not do so), but for the - the space gets retained
and is then considered a separator between macro arguments.
Fix the respective definitions for both the - and + cases, so that they
neither contain spaces nor make cpp insert any (the latter by adding
seemingly redundant parentheses).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4CBDBEBA020000780001E05A@vpn.id2.novell.com>
Cc: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Impact: stack protector for x86_32
Implement stack protector for x86_32. GDT entry 28 is used for it.
It's set to point to stack_canary-20 and have the length of 24 bytes.
CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs
to the stack canary segment on entry. As %gs is otherwise unused by
the kernel, the canary can be anywhere. It's defined as a percpu
variable.
x86_32 exception handlers take register frame on stack directly as
struct pt_regs. With -fstack-protector turned on, gcc copies the
whole structure after the stack canary and (of course) doesn't copy
back on return thus losing all changed. For now, -fno-stack-protector
is added to all files which contain those functions. We definitely
need something better.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:
a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
