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/boot/opal-calls.S | 67 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 arch/powerpc/boot/opal-calls.S (limited to 'arch/powerpc/boot/opal-calls.S') diff --git a/arch/powerpc/boot/opal-calls.S b/arch/powerpc/boot/opal-calls.S new file mode 100644 index 000000000..1f2f330a4 --- /dev/null +++ b/arch/powerpc/boot/opal-calls.S @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (c) 2016 IBM Corporation. + */ + +#include "ppc_asm.h" +#include "../include/asm/opal-api.h" + + .text + + .globl opal_kentry +opal_kentry: + /* r3 is the fdt ptr */ + mtctr r4 + li r4, 0 + li r5, 0 + li r6, 0 + li r7, 0 + LOAD_REG_ADDR(r11, opal) + ld r8,0(r11) + ld r9,8(r11) + bctr + +#define OPAL_CALL(name, token) \ + .globl name; \ +name: \ + li r0, token; \ + b opal_call; + +opal_call: + mflr r11 + std r11,16(r1) + mfcr r12 + stw r12,8(r1) + mr r13,r2 + + /* Set opal return address */ + LOAD_REG_ADDR(r11, opal_return) + mtlr r11 + mfmsr r12 + + /* switch to BE when we enter OPAL */ + li r11,MSR_LE + andc r12,r12,r11 + mtspr SPRN_HSRR1,r12 + + /* load the opal call entry point and base */ + LOAD_REG_ADDR(r11, opal) + ld r12,8(r11) + ld r2,0(r11) + mtspr SPRN_HSRR0,r12 + hrfid + +opal_return: + FIXUP_ENDIAN + mr r2,r13; + lwz r11,8(r1); + ld r12,16(r1) + mtcr r11; + mtlr r12 + blr + +OPAL_CALL(opal_console_write, OPAL_CONSOLE_WRITE); +OPAL_CALL(opal_console_read, OPAL_CONSOLE_READ); +OPAL_CALL(opal_console_write_buffer_space, OPAL_CONSOLE_WRITE_BUFFER_SPACE); +OPAL_CALL(opal_poll_events, OPAL_POLL_EVENTS); +OPAL_CALL(opal_console_flush, OPAL_CONSOLE_FLUSH); -- cgit v1.3.1