Commit 21ab0b6d authored by Puranjay Mohan's avatar Puranjay Mohan Committed by Daniel Borkmann
Browse files

bpf, riscv: Implement bpf_addr_space_cast instruction 



LLVM generates bpf_addr_space_cast instruction while translating
pointers between native (zero) address space and
__attribute__((address_space(N))). The addr_space=0 is reserved as
bpf_arena address space.

rY = addr_space_cast(rX, 0, 1) is processed by the verifier and
converted to normal 32-bit move: wX = wY

rY = addr_space_cast(rX, 1, 0) has to be converted by JIT.

Signed-off-by: default avatarPuranjay Mohan <puranjay12@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Tested-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Tested-by: default avatarPu Lehui <pulehui@huawei.com>
Reviewed-by: default avatarPu Lehui <pulehui@huawei.com>
Acked-by: default avatarBjörn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20240404114203.105970-3-puranjay12@gmail.com
parent 633a6e01

arch/riscv/net/bpf_jit.h

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ struct rv_jit_context { 
	unsigned long flags;

	int stack_size;

	u64 arena_vm_start;

	u64 user_vm_start;

};



/* Convert from ninsns to bytes. */

arch/riscv/net/bpf_jit_comp64.c

+14 −0
Original line number Diff line number Diff line
@@ -1081,6 +1081,15 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, 
	/* dst = src */

	case BPF_ALU | BPF_MOV | BPF_X:

	case BPF_ALU64 | BPF_MOV | BPF_X:

		if (insn_is_cast_user(insn)) {

			emit_mv(RV_REG_T1, rs, ctx);

			emit_zextw(RV_REG_T1, RV_REG_T1, ctx);

			emit_imm(rd, (ctx->user_vm_start >> 32) << 32, ctx);

			emit(rv_beq(RV_REG_T1, RV_REG_ZERO, 4), ctx);

			emit_or(RV_REG_T1, rd, RV_REG_T1, ctx);

			emit_mv(rd, RV_REG_T1, ctx);

			break;

		}

		if (imm == 1) {

			/* Special mov32 for zext */

			emit_zextw(rd, rd, ctx);
@@ -2024,3 +2033,8 @@ bool bpf_jit_supports_ptr_xchg(void) 
{

	return true;

}



bool bpf_jit_supports_arena(void)

{

	return true;

}

arch/riscv/net/bpf_jit_core.c

+1 −0
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) 
	}



	ctx->arena_vm_start = bpf_arena_get_kern_vm_start(prog->aux->arena);

	ctx->user_vm_start = bpf_arena_get_user_vm_start(prog->aux->arena);

	ctx->prog = prog;

	ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);

	if (!ctx->offset) {