On 28.11.2023 11:03, Roger Pau Monne wrote: > Introduce a basic livepatch test using the interface to run self modifying > tests. The introduced test relies on changing a function from returning false > to returning true. > > To simplify the burden of keeping a patch that can be provided to > livepatch-build-tools, introduce two new files: one containing the unpatched > test functions, and another one that contains the patched forms of such > functions. Note that only the former is linked into the Xen image, the latter > is built but the object file is not consumed afterwards. Do this to assert > that the file containing the patched functions continues to build. > > Since livepatch testing will ensure that the functions are not patched > previous > the applying the livepatch, allow the livepatch related tests to fail without > tainting the hypervisor. > > Note the livepatch tests are not run as part of the self modifying checks > executed during boot, as they would obviously fail. > > Signed-off-by: Roger Pau Monné <[email protected]> > --- > Changes since v1: > - New interface & test. > --- > tools/misc/xen-livepatch.c | 29 +++++++++++++++++++++++++++++ > xen/arch/x86/Makefile | 2 ++ > xen/arch/x86/include/asm/test-smc.h | 2 ++ > xen/arch/x86/setup.c | 2 +- > xen/arch/x86/test-smc-lp-alt.c | 23 +++++++++++++++++++++++ > xen/arch/x86/test-smc-lp.c | 23 +++++++++++++++++++++++ > xen/arch/x86/test-smc.c | 11 ++++++++++- > xen/include/public/sysctl.h | 6 +++++- > 8 files changed, 95 insertions(+), 3 deletions(-) > create mode 100644 xen/arch/x86/test-smc-lp-alt.c > create mode 100644 xen/arch/x86/test-smc-lp.c
Can these (and perhaps also the one file introduced earlier in the series) perhaps become xen/arch/x86/test/smc*.c? > --- /dev/null > +++ b/xen/arch/x86/test-smc-lp-alt.c > @@ -0,0 +1,23 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +#include <asm/test-smc.h> > + > +/* > + * Interesting case because `return false` can be encoded as an xor > + * instruction, which is shorter than `return true` which is a mov > instruction, > + * and also shorter than a jmp instruction. > + */ I'm a little wary of this comment: "mov $1, %al" is two bytes only, just like "xor %eax, %eax" is. > +bool cf_check test_lp_insn_replacement(void) What's the purpose of the cf_check here? Jan
