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/powerpc/math-emu/fcmpo.c | 48 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 arch/powerpc/math-emu/fcmpo.c (limited to 'arch/powerpc/math-emu/fcmpo.c') diff --git a/arch/powerpc/math-emu/fcmpo.c b/arch/powerpc/math-emu/fcmpo.c new file mode 100644 index 000000000..f437d0896 --- /dev/null +++ b/arch/powerpc/math-emu/fcmpo.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +#include +#include +#include + +int +fcmpo(u32 *ccr, int crfD, void *frA, void *frB) +{ + FP_DECL_D(A); + FP_DECL_D(B); + FP_DECL_EX; + int code[4] = { (1 << 3), (1 << 1), (1 << 2), (1 << 0) }; + long cmp; + +#ifdef DEBUG + printk("%s: %p (%08x) %d %p %p\n", __func__, ccr, *ccr, crfD, frA, frB); +#endif + + FP_UNPACK_DP(A, frA); + FP_UNPACK_DP(B, frB); + +#ifdef DEBUG + printk("A: %ld %lu %lu %ld (%ld)\n", A_s, A_f1, A_f0, A_e, A_c); + printk("B: %ld %lu %lu %ld (%ld)\n", B_s, B_f1, B_f0, B_e, B_c); +#endif + + if (A_c == FP_CLS_NAN || B_c == FP_CLS_NAN) + FP_SET_EXCEPTION(EFLAG_VXVC); + + FP_CMP_D(cmp, A, B, 2); + cmp = code[(cmp + 1) & 3]; + + __FPU_FPSCR &= ~(0x1f000); + __FPU_FPSCR |= (cmp << 12); + + *ccr &= ~(15 << ((7 - crfD) << 2)); + *ccr |= (cmp << ((7 - crfD) << 2)); + +#ifdef DEBUG + printk("CR: %08x\n", *ccr); +#endif + + return FP_CUR_EXCEPTIONS; +} -- cgit v1.3.1