Parse USDT arguments like "8@(%rsp)" on x86. These are emmited by systemtap. The syntax is a mixture between the "memory dereference case" and the "register read case" as the offset is zero but the register is wrapped in parentheses. We treat them the same as the the "register read case". I've tested that this fixes the "unrecognized arg #N spec: 8@(%rsp).." error I've run into when attaching to a probe with such an argument. Attaching and reading the arguments works. Something similar might be needed for the other supported architectures. ref: https://github.com/libbpf/libbpf/issues/559 Signed-off-by: Timo Hunziker <timo.hunziker@xxxxxx> --- tools/lib/bpf/usdt.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c index b8daae265f99..5e7ec7ad8ad7 100644 --- a/tools/lib/bpf/usdt.c +++ b/tools/lib/bpf/usdt.c @@ -1233,6 +1233,14 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec if (reg_off < 0) return reg_off; arg->reg_off = reg_off; + } else if (sscanf(arg_str, " %d @ ( %%%15[^)] ) %n", &arg_sz, reg_name, &len) == 2) { + /* Register read case with parentheses, e.g., 8@(%rsp) */ + arg->arg_type = USDT_ARG_REG; + arg->val_off = 0; + reg_off = calc_pt_regs_off(reg_name); + if (reg_off < 0) + return reg_off; + arg->reg_off = reg_off; } else if (sscanf(arg_str, " %d @ %%%15s %n", &arg_sz, reg_name, &len) == 2) { /* Register read case, e.g., -4@%eax */ arg->arg_type = USDT_ARG_REG; -- 2.36.2
