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authorNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>2022-01-06 14:45:12 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2022-01-15 04:21:25 +0300
commit3f5f766d5f7f95a69a630da3544a1a0cee1cdddf (patch)
tree8a7dc3a6de0810d2cc7a72c889b75bc650c8d9a1 /arch/powerpc/net
parent88a71086c48ae98e93c0208044827621e9717f7e (diff)
downloadlinux-3f5f766d5f7f95a69a630da3544a1a0cee1cdddf.tar.xz
powerpc64/bpf: Limit 'ldbrx' to processors compliant with ISA v2.06
Johan reported the below crash with test_bpf on ppc64 e5500: test_bpf: #296 ALU_END_FROM_LE 64: 0x0123456789abcdef -> 0x67452301 jited:1 Oops: Exception in kernel mode, sig: 4 [#1] BE PAGE_SIZE=4K SMP NR_CPUS=24 QEMU e500 Modules linked in: test_bpf(+) CPU: 0 PID: 76 Comm: insmod Not tainted 5.14.0-03771-g98c2059e008a-dirty #1 NIP: 8000000000061c3c LR: 80000000006dea64 CTR: 8000000000061c18 REGS: c0000000032d3420 TRAP: 0700 Not tainted (5.14.0-03771-g98c2059e008a-dirty) MSR: 0000000080089000 <EE,ME> CR: 88002822 XER: 20000000 IRQMASK: 0 <...> NIP [8000000000061c3c] 0x8000000000061c3c LR [80000000006dea64] .__run_one+0x104/0x17c [test_bpf] Call Trace: .__run_one+0x60/0x17c [test_bpf] (unreliable) .test_bpf_init+0x6a8/0xdc8 [test_bpf] .do_one_initcall+0x6c/0x28c .do_init_module+0x68/0x28c .load_module+0x2460/0x2abc .__do_sys_init_module+0x120/0x18c .system_call_exception+0x110/0x1b8 system_call_common+0xf0/0x210 --- interrupt: c00 at 0x101d0acc <...> ---[ end trace 47b2bf19090bb3d0 ]--- Illegal instruction The illegal instruction turned out to be 'ldbrx' emitted for BPF_FROM_[L|B]E, which was only introduced in ISA v2.06. Guard use of the same and implement an alternative approach for older processors. Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF") Reported-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/d1e51c6fdf572062cf3009a751c3406bda01b832.1641468127.git.naveen.n.rao@linux.vnet.ibm.com
Diffstat (limited to 'arch/powerpc/net')
-rw-r--r--arch/powerpc/net/bpf_jit_comp64.c22
1 files changed, 13 insertions, 9 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index bfdd417c6b81..e1e8c934308a 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -634,17 +634,21 @@ bpf_alu32_trunc:
EMIT(PPC_RAW_MR(dst_reg, b2p[TMP_REG_1]));
break;
case 64:
- /*
- * Way easier and faster(?) to store the value
- * into stack and then use ldbrx
- *
- * ctx->seen will be reliable in pass2, but
- * the instructions generated will remain the
- * same across all passes
- */
+ /* Store the value to stack and then use byte-reverse loads */
PPC_BPF_STL(dst_reg, 1, bpf_jit_stack_local(ctx));
EMIT(PPC_RAW_ADDI(b2p[TMP_REG_1], 1, bpf_jit_stack_local(ctx)));
- EMIT(PPC_RAW_LDBRX(dst_reg, 0, b2p[TMP_REG_1]));
+ if (cpu_has_feature(CPU_FTR_ARCH_206)) {
+ EMIT(PPC_RAW_LDBRX(dst_reg, 0, b2p[TMP_REG_1]));
+ } else {
+ EMIT(PPC_RAW_LWBRX(dst_reg, 0, b2p[TMP_REG_1]));
+ if (IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN))
+ EMIT(PPC_RAW_SLDI(dst_reg, dst_reg, 32));
+ EMIT(PPC_RAW_LI(b2p[TMP_REG_2], 4));
+ EMIT(PPC_RAW_LWBRX(b2p[TMP_REG_2], b2p[TMP_REG_2], b2p[TMP_REG_1]));
+ if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+ EMIT(PPC_RAW_SLDI(b2p[TMP_REG_2], b2p[TMP_REG_2], 32));
+ EMIT(PPC_RAW_OR(dst_reg, dst_reg, b2p[TMP_REG_2]));
+ }
break;
}
break;