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bpf: Disasm support for addr_space_cast instruction. 

LLVM generates rX = addr_space_cast(rY, dst_addr_space, src_addr_space)
instruction when pointers in non-zero address space are used by the bpf
program. Recognize this insn in uapi and in bpf disassembler.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20240308010812.89848-3-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2024-03-07 17:08:00 -08:00 committed by Andrii Nakryiko
parent 317460317a
commit 667a86ad9b
3 changed files with 18 additions and 0 deletions
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4
include/uapi/linux/bpf.h
View File

@ -1339,6 +1339,10 @@ enum {
*/ */
#define BPF_PSEUDO_KFUNC_CALL 2 #define BPF_PSEUDO_KFUNC_CALL 2
enum bpf_addr_space_cast {
BPF_ADDR_SPACE_CAST = 1,
};
/* flags for BPF_MAP_UPDATE_ELEM command */ /* flags for BPF_MAP_UPDATE_ELEM command */
enum { enum {
BPF_ANY = 0, /* create new element or update existing */ BPF_ANY = 0, /* create new element or update existing */

10
kernel/bpf/disasm.c
View File

@ -166,6 +166,12 @@ static bool is_movsx(const struct bpf_insn *insn)
(insn->off == 8 || insn->off == 16 || insn->off == 32); (insn->off == 8 || insn->off == 16 || insn->off == 32);
} }
static bool is_addr_space_cast(const struct bpf_insn *insn)
{
return insn->code == (BPF_ALU64 | BPF_MOV | BPF_X) &&
insn->off == BPF_ADDR_SPACE_CAST;
}
void print_bpf_insn(const struct bpf_insn_cbs *cbs, void print_bpf_insn(const struct bpf_insn_cbs *cbs,
const struct bpf_insn *insn, const struct bpf_insn *insn,
bool allow_ptr_leaks) bool allow_ptr_leaks)
@ -184,6 +190,10 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
insn->code, class == BPF_ALU ? 'w' : 'r', insn->code, class == BPF_ALU ? 'w' : 'r',
insn->dst_reg, class == BPF_ALU ? 'w' : 'r', insn->dst_reg, class == BPF_ALU ? 'w' : 'r',
insn->dst_reg); insn->dst_reg);
} else if (is_addr_space_cast(insn)) {
verbose(cbs->private_data, "(%02x) r%d = addr_space_cast(r%d, %d, %d)\n",
insn->code, insn->dst_reg,
insn->src_reg, ((u32)insn->imm) >> 16, (u16)insn->imm);
} else if (BPF_SRC(insn->code) == BPF_X) { } else if (BPF_SRC(insn->code) == BPF_X) {
verbose(cbs->private_data, "(%02x) %c%d %s %s%c%d\n", verbose(cbs->private_data, "(%02x) %c%d %s %s%c%d\n",
insn->code, class == BPF_ALU ? 'w' : 'r', insn->code, class == BPF_ALU ? 'w' : 'r',

4
tools/include/uapi/linux/bpf.h
View File

@ -1339,6 +1339,10 @@ enum {
*/ */
#define BPF_PSEUDO_KFUNC_CALL 2 #define BPF_PSEUDO_KFUNC_CALL 2
enum bpf_addr_space_cast {
BPF_ADDR_SPACE_CAST = 1,
};
/* flags for BPF_MAP_UPDATE_ELEM command */ /* flags for BPF_MAP_UPDATE_ELEM command */
enum { enum {
BPF_ANY = 0, /* create new element or update existing */ BPF_ANY = 0, /* create new element or update existing */