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/mips/jazz/reset.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 arch/mips/jazz/reset.c (limited to 'arch/mips/jazz/reset.c') diff --git a/arch/mips/jazz/reset.c b/arch/mips/jazz/reset.c new file mode 100644 index 000000000..052b01f5d --- /dev/null +++ b/arch/mips/jazz/reset.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Reset a Jazz machine. + * + * We don't trust the firmware so we do it the classic way by poking and + * stabbing at the keyboard controller ... + */ +#include +#include + +#define KBD_STAT_IBF 0x02 /* Keyboard input buffer full */ + +static void jazz_write_output(unsigned char val) +{ + int status; + + do { + status = jazz_kh->command; + } while (status & KBD_STAT_IBF); + jazz_kh->data = val; +} + +static void jazz_write_command(unsigned char val) +{ + int status; + + do { + status = jazz_kh->command; + } while (status & KBD_STAT_IBF); + jazz_kh->command = val; +} + +static unsigned char jazz_read_status(void) +{ + return jazz_kh->command; +} + +static inline void kb_wait(void) +{ + unsigned long start = jiffies; + unsigned long timeout = start + HZ/2; + + do { + if (! (jazz_read_status() & 0x02)) + return; + } while (time_before_eq(jiffies, timeout)); +} + +void jazz_machine_restart(char *command) +{ + while(1) { + kb_wait(); + jazz_write_command(0xd1); + kb_wait(); + jazz_write_output(0x00); + } +} -- cgit v1.3.1