From: Masami Hiramatsu (Google) <[email protected]> Cleanup __store_entry_arg() so that it is easier to understand. The main complexity may come from combining the loops for finding stored-entry-arg and max-offset and appending new entry.
This split those different loops into 3 parts, lookup the same entry-arg, find the max offset and append new entry. Signed-off-by: Masami Hiramatsu (Google) <[email protected]> --- kernel/trace/trace_probe.c | 85 +++++++++++++++++++++++--------------------- 1 file changed, 44 insertions(+), 41 deletions(-) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 2eeecb6c95ee..b2261cab4b94 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -770,6 +770,26 @@ static int check_prepare_btf_string_fetch(char *typename, #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API +static void store_entry_arg_at(struct fetch_insn *code, int argnum, int offset) +{ + code[0].op = FETCH_OP_ARG; + code[0].param = argnum; + code[1].op = FETCH_OP_ST_EDATA; + code[1].offset = offset; +} + +static int get_entry_arg_max_offset(struct probe_entry_arg *earg) +{ + int i, max_offset = 0; + + for (i = 0; i < earg->size - 1 && earg->code[i].op != FETCH_OP_END; i++) { + if (earg->code[i].op == FETCH_OP_ST_EDATA) + if (earg->code[i].offset > max_offset) + max_offset = earg->code[i].offset; + } + return max_offset; +} + /* * Add the entry code to store the 'argnum'th parameter and return the offset * in the entry data buffer where the data will be stored. @@ -777,7 +797,6 @@ static int check_prepare_btf_string_fetch(char *typename, static int __store_entry_arg(struct trace_probe *tp, int argnum) { struct probe_entry_arg *earg = tp->entry_arg; - bool match = false; int i, offset; if (!earg) { @@ -795,6 +814,8 @@ static int __store_entry_arg(struct trace_probe *tp, int argnum) for (i = 0; i < earg->size; i++) earg->code[i].op = FETCH_OP_END; tp->entry_arg = earg; + store_entry_arg_at(earg->code, argnum, 0); + return 0; } /* @@ -806,40 +827,34 @@ static int __store_entry_arg(struct trace_probe *tp, int argnum) * code array to find the FETCH_OP_ARG which already fetches the 'argnum' * parameter. If it doesn't match, update 'offset' to find the last * offset. - * If we find the FETCH_OP_END without matching FETCH_OP_ARG entry, we - * will save the entry with FETCH_OP_ARG and FETCH_OP_ST_EDATA, and - * return data offset so that caller can find the data offset in the entry - * data buffer. + * If we hit the FETCH_OP_END without matching FETCH_OP_ARG entry, + * append the entry with FETCH_OP_ARG and FETCH_OP_ST_EDATA, and + * return data offset so that caller can find the data offset in the + * entry data buffer. */ - offset = 0; - for (i = 0; i < earg->size - 1; i++) { - switch (earg->code[i].op) { - case FETCH_OP_END: - earg->code[i].op = FETCH_OP_ARG; - earg->code[i].param = argnum; - earg->code[i + 1].op = FETCH_OP_ST_EDATA; - earg->code[i + 1].offset = offset; - return offset; - case FETCH_OP_ARG: - match = (earg->code[i].param == argnum); - break; - case FETCH_OP_ST_EDATA: - offset = earg->code[i].offset; - if (match) - return offset; - offset += sizeof(unsigned long); - break; - default: - break; - } + + /* Search the offset for the sprcified argnum. */ + for (i = 0; i < earg->size - 1 && earg->code[i].op != FETCH_OP_END; i++) { + if (earg->code[i].op != FETCH_OP_ARG || earg->code[i].param != argnum) + continue; + + if (WARN_ON_ONCE(earg->code[i + 1].op != FETCH_OP_ST_EDATA)) + continue; + + return earg->code[i + 1].offset; } - return -ENOSPC; + if (i >= earg->size - 1) + return -ENOSPC; + + /* Not found, append new entry if possible. */ + offset = get_entry_arg_max_offset(earg) + sizeof(unsigned long); + store_entry_arg_at(&earg->code[i], argnum, offset); + return offset; } int traceprobe_get_entry_data_size(struct trace_probe *tp) { struct probe_entry_arg *earg = tp->entry_arg; - int i, size = 0; if (!earg) return 0; @@ -854,19 +869,7 @@ int traceprobe_get_entry_data_size(struct trace_probe *tp) * stored. Thus we need to find the last FETCH_OP_ST_EDATA in the * code array. */ - for (i = 0; i < earg->size; i++) { - switch (earg->code[i].op) { - case FETCH_OP_END: - goto out; - case FETCH_OP_ST_EDATA: - size = earg->code[i].offset + sizeof(unsigned long); - break; - default: - break; - } - } -out: - return size; + return get_entry_arg_max_offset(earg) + sizeof(unsigned long); } void store_trace_entry_data(void *edata, struct trace_probe *tp, struct pt_regs *regs)
