From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- arch/xtensa/Kconfig.debug | 48 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 arch/xtensa/Kconfig.debug (limited to 'arch/xtensa/Kconfig.debug') diff --git a/arch/xtensa/Kconfig.debug b/arch/xtensa/Kconfig.debug new file mode 100644 index 000000000..e84172a77 --- /dev/null +++ b/arch/xtensa/Kconfig.debug @@ -0,0 +1,48 @@ +# SPDX-License-Identifier: GPL-2.0 + +config DEBUG_TLB_SANITY + bool "Debug TLB sanity" + depends on DEBUG_KERNEL && MMU + help + Enable this to turn on TLB sanity check on each entry to userspace. + This check can spot missing TLB invalidation/wrong PTE permissions/ + premature page freeing. + + If unsure, say N. + +config LD_NO_RELAX + bool "Disable linker relaxation" + default y + help + Enable this function to disable link-time optimizations. + The default linker behavior is to combine identical literal + values to reduce code size and remove unnecessary overhead from + assembler-generated 'longcall' sequences. + Enabling this option improves the link time but increases the + code size, and possibly execution time. + +config S32C1I_SELFTEST + bool "Perform S32C1I instruction self-test at boot" + default y + help + Enable this option to test S32C1I instruction behavior at boot. + Correct operation of this instruction requires some cooperation from hardware + external to the processor (such as bus bridge, bus fabric, or memory controller). + It is easy to make wrong hardware configuration, this test should catch it early. + + Say 'N' on stable hardware. + +config PRINT_STACK_DEPTH + int "Stack depth to print" if DEBUG_KERNEL + default 64 + help + This option allows you to set the stack depth that the kernel + prints in stack traces. + +config PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION + bool "Dump user code around unhandled exception address" + help + Enable this option to display user code around PC of the unhandled + exception (starting at address aligned on 16 byte boundary). + This may simplify finding faulting code in the absence of other + debug facilities. -- cgit v1.3.1