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/of.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 arch/powerpc/boot/of.c (limited to 'arch/powerpc/boot/of.c') diff --git a/arch/powerpc/boot/of.c b/arch/powerpc/boot/of.c new file mode 100644 index 000000000..2fbd4ae60 --- /dev/null +++ b/arch/powerpc/boot/of.c @@ -0,0 +1,93 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) Paul Mackerras 1997. + */ +#include +#include +#include "types.h" +#include "elf.h" +#include "string.h" +#include "stdio.h" +#include "page.h" +#include "ops.h" + +#include "of.h" + +/* Value picked to match that used by yaboot */ +#define PROG_START 0x01400000 /* only used on 64-bit systems */ +#define RAM_END (512<<20) /* Fixme: use OF */ +#define ONE_MB 0x100000 + + + +static unsigned long claim_base; + +void epapr_platform_init(unsigned long r3, unsigned long r4, unsigned long r5, + unsigned long r6, unsigned long r7); + +static void *of_try_claim(unsigned long size) +{ + unsigned long addr = 0; + + if (claim_base == 0) + claim_base = _ALIGN_UP((unsigned long)_end, ONE_MB); + + for(; claim_base < RAM_END; claim_base += ONE_MB) { +#ifdef DEBUG + printf(" trying: 0x%08lx\n\r", claim_base); +#endif + addr = (unsigned long) of_claim(claim_base, size, 0); + if (addr != PROM_ERROR) + break; + } + if (addr == 0) + return NULL; + claim_base = PAGE_ALIGN(claim_base + size); + return (void *)addr; +} + +static void of_image_hdr(const void *hdr) +{ + const Elf64_Ehdr *elf64 = hdr; + + if (elf64->e_ident[EI_CLASS] == ELFCLASS64) { + /* + * Maintain a "magic" minimum address. This keeps some older + * firmware platforms running. + */ + if (claim_base < PROG_START) + claim_base = PROG_START; + } +} + +static void of_platform_init(unsigned long a1, unsigned long a2, void *promptr) +{ + platform_ops.image_hdr = of_image_hdr; + platform_ops.malloc = of_try_claim; + platform_ops.exit = of_exit; + platform_ops.vmlinux_alloc = of_vmlinux_alloc; + + dt_ops.finddevice = of_finddevice; + dt_ops.getprop = of_getprop; + dt_ops.setprop = of_setprop; + + of_console_init(); + + of_init(promptr); + loader_info.promptr = promptr; + if (a1 && a2 && a2 != 0xdeadbeef) { + loader_info.initrd_addr = a1; + loader_info.initrd_size = a2; + } +} + +void platform_init(unsigned long r3, unsigned long r4, unsigned long r5, + unsigned long r6, unsigned long r7) +{ + /* Detect OF vs. ePAPR boot */ + if (r5) + of_platform_init(r3, r4, (void *)r5); + else + epapr_platform_init(r3, r4, r5, r6, r7); +} + -- cgit v1.3.1