diff options
| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2026-09-04 10:43:19 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-09-04 07:58:36 -0700 |
| commit | 6668ed271eaefaa63e686bdfbedaeb7b8e492722 (patch) | |
| tree | 58e8288fead484f6755ad0815fc74c3742663761 /arch/arm/mm/tlb-fa.S | |
| download | linux-stable-6668ed271eaefaa63e686bdfbedaeb7b8e492722.tar.gz linux-stable-6668ed271eaefaa63e686bdfbedaeb7b8e492722.zip | |
selftests/bpf: Reject graph kptr use after RCU unlockgrafted
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 <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/arm/mm/tlb-fa.S')
| -rw-r--r-- | arch/arm/mm/tlb-fa.S | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/arch/arm/mm/tlb-fa.S b/arch/arm/mm/tlb-fa.S new file mode 100644 index 000000000..85a6fe766 --- /dev/null +++ b/arch/arm/mm/tlb-fa.S @@ -0,0 +1,65 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/mm/tlb-fa.S + * + * Copyright (C) 2005 Faraday Corp. + * Copyright (C) 2008-2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt> + * + * Based on tlb-v4wbi.S: + * Copyright (C) 1997-2002 Russell King + * + * ARM architecture version 4, Faraday variation. + * This assume an unified TLBs, with a write buffer, and branch target buffer (BTB) + * + * Processors: FA520 FA526 FA626 + */ +#include <linux/linkage.h> +#include <linux/init.h> +#include <linux/cfi_types.h> +#include <asm/assembler.h> +#include <asm/asm-offsets.h> +#include <asm/tlbflush.h> +#include "proc-macros.S" + + +/* + * flush_user_tlb_range(start, end, mm) + * + * Invalidate a range of TLB entries in the specified address space. + * + * - start - range start address + * - end - range end address + * - mm - mm_struct describing address space + */ + .align 4 +SYM_TYPED_FUNC_START(fa_flush_user_tlb_range) + vma_vm_mm ip, r2 + act_mm r3 @ get current->active_mm + eors r3, ip, r3 @ == mm ? + retne lr @ no, we dont do anything + mov r3, #0 + mcr p15, 0, r3, c7, c10, 4 @ drain WB + bic r0, r0, #0x0ff + bic r0, r0, #0xf00 +1: mcr p15, 0, r0, c8, c7, 1 @ invalidate UTLB entry + add r0, r0, #PAGE_SZ + cmp r0, r1 + blo 1b + mcr p15, 0, r3, c7, c10, 4 @ data write barrier + ret lr +SYM_FUNC_END(fa_flush_user_tlb_range) + + +SYM_TYPED_FUNC_START(fa_flush_kern_tlb_range) + mov r3, #0 + mcr p15, 0, r3, c7, c10, 4 @ drain WB + bic r0, r0, #0x0ff + bic r0, r0, #0xf00 +1: mcr p15, 0, r0, c8, c7, 1 @ invalidate UTLB entry + add r0, r0, #PAGE_SZ + cmp r0, r1 + blo 1b + mcr p15, 0, r3, c7, c10, 4 @ data write barrier + mcr p15, 0, r3, c7, c5, 4 @ prefetch flush (isb) + ret lr +SYM_FUNC_END(fa_flush_kern_tlb_range) |