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/mtfsf.c | 52 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 arch/powerpc/math-emu/mtfsf.c (limited to 'arch/powerpc/math-emu/mtfsf.c') diff --git a/arch/powerpc/math-emu/mtfsf.c b/arch/powerpc/math-emu/mtfsf.c new file mode 100644 index 000000000..7ae990f6b --- /dev/null +++ b/arch/powerpc/math-emu/mtfsf.c @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +#include +#include + +int +mtfsf(unsigned int FM, u32 *frB) +{ + u32 mask; + u32 fpscr; + + if (likely(FM == 1)) + mask = 0x0f; + else if (likely(FM == 0xff)) + mask = ~0; + else { + mask = ((FM & 1) | + ((FM << 3) & 0x10) | + ((FM << 6) & 0x100) | + ((FM << 9) & 0x1000) | + ((FM << 12) & 0x10000) | + ((FM << 15) & 0x100000) | + ((FM << 18) & 0x1000000) | + ((FM << 21) & 0x10000000)) * 15; + } + + fpscr = ((__FPU_FPSCR & ~mask) | (frB[1] & mask)) & + ~(FPSCR_VX | FPSCR_FEX | 0x800); + + if (fpscr & (FPSCR_VXSNAN | FPSCR_VXISI | FPSCR_VXIDI | + FPSCR_VXZDZ | FPSCR_VXIMZ | FPSCR_VXVC | + FPSCR_VXSOFT | FPSCR_VXSQRT | FPSCR_VXCVI)) + fpscr |= FPSCR_VX; + + /* The bit order of exception enables and exception status + * is the same. Simply shift and mask to check for enabled + * exceptions. + */ + if (fpscr & (fpscr >> 22) & 0xf8) + fpscr |= FPSCR_FEX; + + __FPU_FPSCR = fpscr; + +#ifdef DEBUG + printk("%s: %02x %p: %08lx\n", __func__, FM, frB, __FPU_FPSCR); +#endif + + return 0; +} -- cgit v1.3.1