"Richard Earnshaw (lists)" <richard.earns...@arm.com> writes: > On 10/06/2024 15:04, Torbjörn SVENSSON wrote: >> Properly handle zero and sign extension for Armv8-M.baseline as >> Cortex-M23 can have the security extension active. >> Currently, there is an internal compiler error on Cortex-M23 for the >> epilog processing of sign extension. >> >> This patch addresses the following CVE-2024-0151 for Armv8-M.baseline. >> >> gcc/ChangeLog: >> >> PR target/115253 >> * config/arm/arm.cc (cmse_nonsecure_call_inline_register_clear): >> Sign extend for Thumb1. >> (thumb1_expand_prologue): Add zero/sign extend. >> >> Signed-off-by: Torbjörn SVENSSON <torbjorn.svens...@foss.st.com> >> Co-authored-by: Yvan ROUX <yvan.r...@foss.st.com> >> --- >> gcc/config/arm/arm.cc | 71 ++++++++++++++++++++++++++++++++++++++----- >> 1 file changed, 63 insertions(+), 8 deletions(-) >> >> diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc >> index ea0c963a4d6..e7b4caf1083 100644 >> --- a/gcc/config/arm/arm.cc >> +++ b/gcc/config/arm/arm.cc >> [...] >> + && known_ge (GET_MODE_SIZE (TYPE_MODE (ret_type)), 2)) > > You can use known_eq here. We'll never have any value other than 2, given > the known_le (4) above and anyway it doesn't make sense to call extendhisi > with any other size.
BTW, I'm surprised we need known_* in arm-specific code. Is it actually needed? Or is this just a conditioned response? ;) Richard
