From 2fe99eb0ccf2bb73df65ebcbbf2f2ff70e63547b Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 7 Mar 2024 17:08:01 -0800 Subject: bpf: Add x86-64 JIT support for PROBE_MEM32 pseudo instructions. Add support for [LDX | STX | ST], PROBE_MEM32, [B | H | W | DW] instructions. They are similar to PROBE_MEM instructions with the following differences: - PROBE_MEM has to check that the address is in the kernel range with src_reg + insn->off >= TASK_SIZE_MAX + PAGE_SIZE check - PROBE_MEM doesn't support store - PROBE_MEM32 relies on the verifier to clear upper 32-bit in the register - PROBE_MEM32 adds 64-bit kern_vm_start address (which is stored in %r12 in the prologue) Due to bpf_arena constructions such %r12 + %reg + off16 access is guaranteed to be within arena virtual range, so no address check at run-time. - PROBE_MEM32 allows STX and ST. If they fault the store is a nop. When LDX faults the destination register is zeroed. Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/bpf/20240308010812.89848-4-alexei.starovoitov@gmail.com --- include/linux/bpf.h | 1 + include/linux/filter.h | 3 +++ 2 files changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ea6ab6e0eef9..8904d1606125 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1458,6 +1458,7 @@ struct bpf_prog_aux { bool xdp_has_frags; bool exception_cb; bool exception_boundary; + struct bpf_arena *arena; /* BTF_KIND_FUNC_PROTO for valid attach_btf_id */ const struct btf_type *attach_func_proto; /* function name for valid attach_btf_id */ diff --git a/include/linux/filter.h b/include/linux/filter.h index 36cc29a2934c..b119f04ecb0b 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -72,6 +72,9 @@ struct ctl_table_header; /* unused opcode to mark special ldsx instruction. Same as BPF_IND */ #define BPF_PROBE_MEMSX 0x40 +/* unused opcode to mark special load instruction. Same as BPF_MSH */ +#define BPF_PROBE_MEM32 0xa0 + /* unused opcode to mark call to interpreter with arguments */ #define BPF_CALL_ARGS 0xe0 -- cgit