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tracing/probes: Cleanup probe argument parser
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Cleanup traceprobe_parse_probe_arg_body() to split out the
type parser and post-processing part of fetch_insn.
This makes no functional change.

Link: https://lore.kernel.org/all/170952362603.229804.9942703761682605372.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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@mhiramat
mhiramat committed Mar 6, 2024
1 parent 7e37b6b commit 032330a
Showing 1 changed file with 137 additions and 93 deletions.
230 changes: 137 additions & 93 deletions kernel/trace/trace_probe.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1090,67 +1090,45 @@ static int __parse_bitfield_probe_arg(const char *bf,
return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
}

/* String length checking wrapper */
static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
struct probe_arg *parg,
struct traceprobe_parse_context *ctx)
/* Split type part from @arg and return it. */
static char *parse_probe_arg_type(char *arg, struct probe_arg *parg,
struct traceprobe_parse_context *ctx)
{
struct fetch_insn *code, *scode, *tmp = NULL;
char *t, *t2, *t3;
int ret, len;
char *arg;
char *t = NULL, *t2, *t3;
int offs;

arg = kstrdup(argv, GFP_KERNEL);
if (!arg)
return -ENOMEM;

ret = -EINVAL;
len = strlen(arg);
if (len > MAX_ARGSTR_LEN) {
trace_probe_log_err(ctx->offset, ARG_TOO_LONG);
goto out;
} else if (len == 0) {
trace_probe_log_err(ctx->offset, NO_ARG_BODY);
goto out;
}

ret = -ENOMEM;
parg->comm = kstrdup(arg, GFP_KERNEL);
if (!parg->comm)
goto out;

ret = -EINVAL;
t = strchr(arg, ':');
if (t) {
*t = '\0';
t2 = strchr(++t, '[');
*t++ = '\0';
t2 = strchr(t, '[');
if (t2) {
*t2++ = '\0';
t3 = strchr(t2, ']');
if (!t3) {
int offs = t2 + strlen(t2) - arg;
offs = t2 + strlen(t2) - arg;

trace_probe_log_err(ctx->offset + offs,
ARRAY_NO_CLOSE);
goto out;
return ERR_PTR(-EINVAL);
} else if (t3[1] != '\0') {
trace_probe_log_err(ctx->offset + t3 + 1 - arg,
BAD_ARRAY_SUFFIX);
goto out;
return ERR_PTR(-EINVAL);
}
*t3 = '\0';
if (kstrtouint(t2, 0, &parg->count) || !parg->count) {
trace_probe_log_err(ctx->offset + t2 - arg,
BAD_ARRAY_NUM);
goto out;
return ERR_PTR(-EINVAL);
}
if (parg->count > MAX_ARRAY_LEN) {
trace_probe_log_err(ctx->offset + t2 - arg,
ARRAY_TOO_BIG);
goto out;
return ERR_PTR(-EINVAL);
}
}
}
offs = t ? t - arg : 0;

/*
* Since $comm and immediate string can not be dereferenced,
Expand All @@ -1161,74 +1139,52 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
strncmp(arg, "\\\"", 2) == 0)) {
/* The type of $comm must be "string", and not an array type. */
if (parg->count || (t && strcmp(t, "string"))) {
trace_probe_log_err(ctx->offset + (t ? (t - arg) : 0),
NEED_STRING_TYPE);
goto out;
trace_probe_log_err(ctx->offset + offs, NEED_STRING_TYPE);
return ERR_PTR(-EINVAL);
}
parg->type = find_fetch_type("string", ctx->flags);
} else
parg->type = find_fetch_type(t, ctx->flags);

if (!parg->type) {
trace_probe_log_err(ctx->offset + (t ? (t - arg) : 0), BAD_TYPE);
goto out;
trace_probe_log_err(ctx->offset + offs, BAD_TYPE);
return ERR_PTR(-EINVAL);
}

code = tmp = kcalloc(FETCH_INSN_MAX, sizeof(*code), GFP_KERNEL);
if (!code)
goto out;
code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;

ctx->last_type = NULL;
ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
ctx);
if (ret)
goto fail;

/* Update storing type if BTF is available */
if (IS_ENABLED(CONFIG_PROBE_EVENTS_BTF_ARGS) &&
ctx->last_type) {
if (!t) {
parg->type = find_fetch_type_from_btf_type(ctx);
} else if (strstr(t, "string")) {
ret = check_prepare_btf_string_fetch(t, &code, ctx);
if (ret)
goto fail;
}
}
parg->offset = *size;
*size += parg->type->size * (parg->count ?: 1);
return t;
}

if (parg->count) {
len = strlen(parg->type->fmttype) + 6;
parg->fmt = kmalloc(len, GFP_KERNEL);
if (!parg->fmt) {
ret = -ENOMEM;
goto out;
}
snprintf(parg->fmt, len, "%s[%d]", parg->type->fmttype,
parg->count);
}
/* After parsing, adjust the fetch_insn according to the probe_arg */
static int finalize_fetch_insn(struct fetch_insn *code,
struct probe_arg *parg,
char *type,
int type_offset,
struct traceprobe_parse_context *ctx)
{
struct fetch_insn *scode;
int ret;

ret = -EINVAL;
/* Store operation */
if (parg->type->is_string) {
/* Check bad combination of the type and the last fetch_insn. */
if (!strcmp(parg->type->name, "symstr")) {
if (code->op != FETCH_OP_REG && code->op != FETCH_OP_STACK &&
code->op != FETCH_OP_RETVAL && code->op != FETCH_OP_ARG &&
code->op != FETCH_OP_DEREF && code->op != FETCH_OP_TP_ARG) {
trace_probe_log_err(ctx->offset + (t ? (t - arg) : 0),
trace_probe_log_err(ctx->offset + type_offset,
BAD_SYMSTRING);
goto fail;
return -EINVAL;
}
} else {
if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_UDEREF &&
code->op != FETCH_OP_IMM && code->op != FETCH_OP_COMM &&
code->op != FETCH_OP_DATA && code->op != FETCH_OP_TP_ARG) {
trace_probe_log_err(ctx->offset + (t ? (t - arg) : 0),
trace_probe_log_err(ctx->offset + type_offset,
BAD_STRING);
goto fail;
return -EINVAL;
}
}

if (!strcmp(parg->type->name, "symstr") ||
(code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM ||
code->op == FETCH_OP_DATA) || code->op == FETCH_OP_TP_ARG ||
Expand All @@ -1244,9 +1200,10 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
code++;
if (code->op != FETCH_OP_NOP) {
trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
goto fail;
return -EINVAL;
}
}

/* If op == DEREF, replace it with STRING */
if (!strcmp(parg->type->name, "ustring") ||
code->op == FETCH_OP_UDEREF)
Expand All @@ -1267,47 +1224,134 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
code++;
if (code->op != FETCH_OP_NOP) {
trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
goto fail;
return -E2BIG;
}
code->op = FETCH_OP_ST_RAW;
code->size = parg->type->size;
}

/* Save storing fetch_insn. */
scode = code;

/* Modify operation */
if (t != NULL) {
ret = __parse_bitfield_probe_arg(t, parg->type, &code);
if (type != NULL) {
/* Bitfield needs a special fetch_insn. */
ret = __parse_bitfield_probe_arg(type, parg->type, &code);
if (ret) {
trace_probe_log_err(ctx->offset + t - arg, BAD_BITFIELD);
goto fail;
trace_probe_log_err(ctx->offset + type_offset, BAD_BITFIELD);
return ret;
}
} else if (IS_ENABLED(CONFIG_PROBE_EVENTS_BTF_ARGS) &&
ctx->last_type) {
/* If user not specified the type, try parsing BTF bitfield. */
ret = parse_btf_bitfield(&code, ctx);
if (ret)
goto fail;
return ret;
}
ret = -EINVAL;

/* Loop(Array) operation */
if (parg->count) {
if (scode->op != FETCH_OP_ST_MEM &&
scode->op != FETCH_OP_ST_STRING &&
scode->op != FETCH_OP_ST_USTRING) {
trace_probe_log_err(ctx->offset + (t ? (t - arg) : 0),
BAD_STRING);
goto fail;
trace_probe_log_err(ctx->offset + type_offset, BAD_STRING);
return -EINVAL;
}
code++;
if (code->op != FETCH_OP_NOP) {
trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
goto fail;
return -E2BIG;
}
code->op = FETCH_OP_LP_ARRAY;
code->param = parg->count;
}

/* Finalize the fetch_insn array. */
code++;
code->op = FETCH_OP_END;

ret = 0;
return 0;
}

/* String length checking wrapper */
static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
struct probe_arg *parg,
struct traceprobe_parse_context *ctx)
{
struct fetch_insn *code, *tmp = NULL;
char *type, *arg;
int ret, len;

len = strlen(argv);
if (len > MAX_ARGSTR_LEN) {
trace_probe_log_err(ctx->offset, ARG_TOO_LONG);
return -E2BIG;
} else if (len == 0) {
trace_probe_log_err(ctx->offset, NO_ARG_BODY);
return -EINVAL;
}

arg = kstrdup(argv, GFP_KERNEL);
if (!arg)
return -ENOMEM;

parg->comm = kstrdup(arg, GFP_KERNEL);
if (!parg->comm) {
ret = -ENOMEM;
goto out;
}

type = parse_probe_arg_type(arg, parg, ctx);
if (IS_ERR(type)) {
ret = PTR_ERR(type);
goto out;
}

code = tmp = kcalloc(FETCH_INSN_MAX, sizeof(*code), GFP_KERNEL);
if (!code) {
ret = -ENOMEM;
goto out;
}
code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;

ctx->last_type = NULL;
ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
ctx);
if (ret < 0)
goto fail;

/* Update storing type if BTF is available */
if (IS_ENABLED(CONFIG_PROBE_EVENTS_BTF_ARGS) &&
ctx->last_type) {
if (!type) {
parg->type = find_fetch_type_from_btf_type(ctx);
} else if (strstr(type, "string")) {
ret = check_prepare_btf_string_fetch(type, &code, ctx);
if (ret)
goto fail;
}
}
parg->offset = *size;
*size += parg->type->size * (parg->count ?: 1);

if (parg->count) {
len = strlen(parg->type->fmttype) + 6;
parg->fmt = kmalloc(len, GFP_KERNEL);
if (!parg->fmt) {
ret = -ENOMEM;
goto out;
}
snprintf(parg->fmt, len, "%s[%d]", parg->type->fmttype,
parg->count);
}

ret = finalize_fetch_insn(code, parg, type, type ? type - arg : 0, ctx);
if (ret < 0)
goto fail;

for (; code < tmp + FETCH_INSN_MAX; code++)
if (code->op == FETCH_OP_END)
break;
/* Shrink down the code buffer */
parg->code = kcalloc(code - tmp + 1, sizeof(*code), GFP_KERNEL);
if (!parg->code)
Expand All @@ -1316,7 +1360,7 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
memcpy(parg->code, tmp, sizeof(*code) * (code - tmp + 1));

fail:
if (ret) {
if (ret < 0) {
for (code = tmp; code < tmp + FETCH_INSN_MAX; code++)
if (code->op == FETCH_NOP_SYMBOL ||
code->op == FETCH_OP_DATA)
Expand Down

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