fnargs: adjust up maximum args capture limits

Allow user to request up to 64KB of data for arguments capture.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

src/env.c

@@ -25,9 +25,9 @@ const char argp_program_doc[] =
 struct env env = {
 	.ringbuf_map_sz = DEFAULT_RINGBUF_SZ,
 	.sessions_map_sz = DEFAULT_SESSIONS_SZ,
-	.args_max_total_args_size = MAX_FNARGS_TOTAL_ARGS_SZ,
-	.args_max_sized_arg_size = MAX_FNARGS_SIZED_ARG_SZ,
-	.args_max_str_arg_size = MAX_FNARGS_STR_ARG_SZ,
+	.args_max_total_args_size = DEFAULT_FNARGS_TOTAL_ARGS_SZ,
+	.args_max_sized_arg_size = DEFAULT_FNARGS_SIZED_ARG_SZ,
+	.args_max_str_arg_size = DEFAULT_FNARGS_STR_ARG_SZ,
 	.args_fmt_max_arg_width = DEFAULT_FNARGS_FMT_MAX_ARG_WIDTH,
 };
 
@@ -694,8 +694,7 @@ void print_config_help_message(void)
 	int i;
 
 	log("It's possible to customize various retsnoop's internal implementation details.\n");
-	log("This can be done by specifying one or multiple extra parameters using\n");
-	log("--config KEY=VALUE CLI arguments.\n\n");
+	log("This can be done by specifying one or multiple extra parameters using --config KEY=VALUE CLI arguments.\n\n");
 
 	log("Supported configuration parameters:\n");
 	for (i = 0; i < ARRAY_SIZE(cfg_specs); i++) {

src/fnargs.c

@@ -147,7 +147,7 @@ int prepare_fn_args_specs(int func_id, const struct mass_attacher_func_info *fin
 		t = btf_strip_mods_and_typedefs(finfo->btf, spec->btf_id, &btf_id);
 		if (btf_is_fixed_sized(finfo->btf, t) || btf_is_ptr(t)) {
 			true_len = btf_is_ptr(t) ? 8 : t->size;
-			data_len = min(true_len, MAX_FNARGS_SIZED_ARG_SZ);
+			data_len = min(true_len, env.args_max_sized_arg_size);
 
 			if (true_len <= 8 && is_arg_in_reg(reg_idx, &reg1_name)) {
 				/* fits in one register */
@@ -194,13 +194,13 @@ int prepare_fn_args_specs(int func_id, const struct mass_attacher_func_info *fin
 			if (btf_is_char(finfo->btf, t)) {
 				/* varlen string */
 				true_len = -1; /* mark that it's variable-length, for logging */
-				data_len = MAX_FNARGS_STR_ARG_SZ;
+				data_len = env.args_max_str_arg_size;
 				spec->arg_flags |= FUNC_ARG_PTR | FUNC_ARG_STR | data_len;
 				spec->pointee_btf_id = -1; /* special string marker */
 				dlog("str");
 			} else if (btf_is_fixed_sized(finfo->btf, t)) {
 				true_len = t->size;
-				data_len = min(true_len, MAX_FNARGS_SIZED_ARG_SZ);
+				data_len = min(true_len, env.args_max_sized_arg_size);
 				spec->arg_flags |= FUNC_ARG_PTR | data_len;
 				dlog("ptr_id=%d", spec->pointee_btf_id);
 			} else {

src/retsnoop.h

@@ -40,39 +40,40 @@ enum func_flags {
 };
 
 #define MAX_FNARGS_ARG_SPEC_CNT 12
-#define MAX_FNARGS_TOTAL_ARGS_SZ 3072	/* total captured args size for all args */
-#define MAX_FNARGS_SIZED_ARG_SZ 256	/* maximum capture size for a single fixed-sized arg */
-#define MAX_FNARGS_STR_ARG_SZ 256	/* maximum capture size for a signel string arg */
-#define MAX_FNARGS_ANY_ARG_SZ \
-	(MAX_FNARGS_SIZED_ARG_SZ > MAX_FNARGS_STR_ARG_SZ \
-		? MAX_FNARGS_SIZED_ARG_SZ : MAX_FNARGS_STR_ARG_SZ)
+#define MAX_FNARGS_TOTAL_ARGS_SZ (64 * 1024)	/* maximum total captured args data size */
+#define MAX_FNARGS_SIZED_ARG_SZ (16 * 1024)	/* maximum capture size for a single fixed-sized arg */
+#define MAX_FNARGS_STR_ARG_SZ (16 * 1024)	/* maximum capture size for a signel string arg */
+
+#define DEFAULT_FNARGS_TOTAL_ARGS_SZ 3072	/* default total captured args data size */
+#define DEFAULT_FNARGS_SIZED_ARG_SZ 256		/* default capture size for a single fixed-sized arg */
+#define DEFAULT_FNARGS_STR_ARG_SZ 256		/* default capture size for a signel string arg */
 
 enum func_arg_flags {
-	/* lowest 12 bits */
-	FUNC_ARG_LEN_MASK = 0x0fff,	/* 4KB bytes max */
+	/* lowest 16 bits */
+	FUNC_ARG_LEN_MASK = 0xffff,	/* 64KB bytes max */
 
 	/* next 4 bits */
-	FUNC_ARG_REG = 0x1000,		/* read specified register */
-	FUNC_ARG_REG_PAIR = 0x2000,	/* read specified register */
-	FUNC_ARG_STACK = 0x4000,	/* read stack at specified offset */
-	FUNC_ARG_PTR = 0x8000,		/* pointer indirection */
+	FUNC_ARG_REG = 0x10000,		/* read specified register */
+	FUNC_ARG_REG_PAIR = 0x20000,	/* read specified register */
+	FUNC_ARG_STACK = 0x40000,	/* read stack at specified offset */
+	FUNC_ARG_PTR = 0x80000,		/* pointer indirection */
 
 	/* "varlen string" marker, uses impossible REG_PAIR + PTR combination */
 	FUNC_ARG_STR = FUNC_ARG_PTR | FUNC_ARG_REG_PAIR,
 
 	/* for REG_PAIR/REG we encode the first/only argument register index */
-	FUNC_ARG_REGIDX_MASK = 0x00ff0000,	/* 1st argument register index */
-	FUNC_ARG_REGIDX_SHIFT = 16,
+	FUNC_ARG_REGIDX_MASK = 0x0ff00000,	/* argument register index */
+	FUNC_ARG_REGIDX_SHIFT = 20,
 
 	/* for STACK we have one big offset */
-	FUNC_ARG_STACKOFF_MASK = 0xffff0000,	/* stack offset */
-	FUNC_ARG_STACKOFF_SHIFT = 16,
+	FUNC_ARG_STACKOFF_MASK = 0xfff00000,	/* stack offset */
+	FUNC_ARG_STACKOFF_SHIFT = 20,
 	FUNC_ARG_STACKOFF_MAX = FUNC_ARG_STACKOFF_MASK >> FUNC_ARG_STACKOFF_SHIFT,
 
 	/* special "skip arg" values, uses special REGIDX value */
-	FUNC_ARG_VARARG			= 0x00fe0000,
-	FUNC_ARG_UNKN			= 0x00fd0000,
-	FUNC_ARG_STACKOFF_2BIG		= 0x00fc0000,
+	FUNC_ARG_VARARG			= 0x0fe00000,
+	FUNC_ARG_UNKN			= 0x0fd00000,
+	FUNC_ARG_STACKOFF_2BIG		= 0x0fc00000,
 };
 
 struct func_info {