On Wed, Jul 15, 2026 at 10:52:27AM +0100, Kees Cook wrote: > +/* UDF base pattern with KCFI bit: cond=0xe, 0x7f, xxxx, 1xxx, 0xf, xxxx */ > +#define CFI_UDF_IMM_BASE 0xe7f008f0 > +#define CFI_UDF_IMM_MASK 0xfff008f0 /* Mask for UDF + KCFI bit > matching */
With this patch applied, KGDB and CONFIG_CFI cannot be used together. Setting a breakpoint causes Oops as CFI failure. This patch on top of "ARM: breakpoint: CFI breakpoints only on demand", multi_v7_defconfig + CONFIG_CFI=y + KGDB/KGDB_KDB/MAGIC_SYSRQ, THUMB2_KERNEL=n, clang 22.1.8 LLVM=1, qemu-system-arm -M virt -cpu cortex-a15, booted with kgdboc=ttyAMA0. Then "echo g > /proc/sysrq-trigger": sysrq: DEBUG CFI failure at kgdb_breakpoint+0x2c/0x58 (target: kgdb_breakpoint+0x2c/0x58; expected type: 0xc0472d70) Internal error: Oops - CFI: 0 [#1] SMP ARM Modules linked in: CPU: 0 UID: 0 PID: 1 Comm: init Not tainted 7.2.0-rc3-00278-g38436106b2f5-dirty #1 VOLUNTARY Hardware name: Generic DT based system PC is at kgdb_breakpoint+0x2c/0x58 LR is at kgdb_breakpoint+0x2c/0x58 pc : [<c0472d70>] lr : [<c0472d70>] psr: 60000013 sp : e080dea8 ip : 00000000 fp : 0021a1c0 r10: 00000000 r9 : 00000000 r8 : c2004048 r7 : c2205d9c r6 : 00000000 r5 : c1609558 r4 : c22bb994 r3 : 00000000 r2 : 00000000 r1 : 00000000 r0 : 00000000 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none ... kgdb_breakpoint from __handle_sysrq+0x150/0x158 Thanks, Karl
