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/dec/wbflush.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 arch/mips/dec/wbflush.c (limited to 'arch/mips/dec/wbflush.c') diff --git a/arch/mips/dec/wbflush.c b/arch/mips/dec/wbflush.c new file mode 100644 index 000000000..dad64d178 --- /dev/null +++ b/arch/mips/dec/wbflush.c @@ -0,0 +1,92 @@ +/* + * Setup the right wbflush routine for the different DECstations. + * + * Created with information from: + * DECstation 3100 Desktop Workstation Functional Specification + * DECstation 5000/200 KN02 System Module Functional Specification + * mipsel-linux-objdump --disassemble vmunix | grep "wbflush" :-) + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 1998 Harald Koerfgen + * Copyright (C) 2002 Maciej W. Rozycki + */ + +#include +#include + +#include +#include +#include + +static void wbflush_kn01(void); +static void wbflush_kn210(void); +static void wbflush_mips(void); + +void (*__wbflush) (void); + +void __init wbflush_setup(void) +{ + switch (mips_machtype) { + case MACH_DS23100: + case MACH_DS5000_200: /* DS5000 3max */ + __wbflush = wbflush_kn01; + break; + case MACH_DS5100: /* DS5100 MIPSMATE */ + __wbflush = wbflush_kn210; + break; + case MACH_DS5000_1XX: /* DS5000/100 3min */ + case MACH_DS5000_XX: /* Personal DS5000/2x */ + case MACH_DS5000_2X0: /* DS5000/240 3max+ */ + case MACH_DS5900: /* DS5900 bigmax */ + default: + __wbflush = wbflush_mips; + break; + } +} + +/* + * For the DS3100 and DS5000/200 the R2020/R3220 writeback buffer functions + * as part of Coprocessor 0. + */ +static void wbflush_kn01(void) +{ + asm(".set\tpush\n\t" + ".set\tnoreorder\n\t" + "1:\tbc0f\t1b\n\t" + "nop\n\t" + ".set\tpop"); +} + +/* + * For the DS5100 the writeback buffer seems to be a part of Coprocessor 3. + * But CP3 has to enabled first. + */ +static void wbflush_kn210(void) +{ + asm(".set\tpush\n\t" + ".set\tnoreorder\n\t" + "mfc0\t$2,$12\n\t" + "lui\t$3,0x8000\n\t" + "or\t$3,$2,$3\n\t" + "mtc0\t$3,$12\n\t" + "nop\n" + "1:\tbc3f\t1b\n\t" + "nop\n\t" + "mtc0\t$2,$12\n\t" + "nop\n\t" + ".set\tpop" + : : : "$2", "$3"); +} + +/* + * I/O ASIC systems use a standard writeback buffer that gets flushed + * upon an uncached read. + */ +static void wbflush_mips(void) +{ + __fast_iob(); +} +EXPORT_SYMBOL(__wbflush); -- cgit v1.3.1