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

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e30d943db8a480e492a2a608839fd51f92246051..3c42b9f1bada3d5bcd7b2608a71bdb277fb1ea6d 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1339,6 +1339,10 @@ enum {
  */
 #define BPF_PSEUDO_KFUNC_CALL  2
 
+enum bpf_addr_space_cast {
+       BPF_ADDR_SPACE_CAST = 1,
+};
+
 /* flags for BPF_MAP_UPDATE_ELEM command */
 enum {
        BPF_ANY         = 0, /* create new element or update existing */

diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c
index 82b2dbdd048f8ec36cccbfc36c8c1949c115a9a2..bd2e2dd04740c1810ba559b67ac9ba69092dc11a 100644 (file)
--- a/kernel/bpf/disasm.c
+++ b/kernel/bpf/disasm.c
@@ -166,6 +166,12 @@ static bool is_movsx(const struct bpf_insn *insn)
               (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,
                    const struct bpf_insn *insn,
                    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->dst_reg, class == BPF_ALU ? 'w' : 'r',
                                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) {
                        verbose(cbs->private_data, "(%02x) %c%d %s %s%c%d\n",
                                insn->code, class == BPF_ALU ? 'w' : 'r',

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index e30d943db8a480e492a2a608839fd51f92246051..3c42b9f1bada3d5bcd7b2608a71bdb277fb1ea6d 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1339,6 +1339,10 @@ enum {
  */
 #define BPF_PSEUDO_KFUNC_CALL  2
 
+enum bpf_addr_space_cast {
+       BPF_ADDR_SPACE_CAST = 1,
+};
+
 /* flags for BPF_MAP_UPDATE_ELEM command */
 enum {
        BPF_ANY         = 0, /* create new element or update existing */