1 files changed, 61 insertions, 11 deletions

diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c
index 3373b9d45ac4..fc2785eecc17 100644
--- a/tools/lib/bpf/usdt.c
+++ b/tools/lib/bpf/usdt.c
@@ -200,12 +200,23 @@ enum usdt_arg_type {
 	USDT_ARG_CONST,
 	USDT_ARG_REG,
 	USDT_ARG_REG_DEREF,
+	USDT_ARG_SIB,
 };
 
 /* should match exactly struct __bpf_usdt_arg_spec from usdt.bpf.h */
 struct usdt_arg_spec {
 	__u64 val_off;
-	enum usdt_arg_type arg_type;
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	enum usdt_arg_type arg_type: 8;
+	__u16	idx_reg_off: 12;
+	__u16	scale_bitshift: 4;
+	__u8 __reserved: 8;     /* keep reg_off offset stable */
+#else
+	__u8 __reserved: 8;     /* keep reg_off offset stable */
+	__u16	idx_reg_off: 12;
+	__u16	scale_bitshift: 4;
+	enum usdt_arg_type arg_type: 8;
+#endif
 	short reg_off;
 	bool arg_signed;
 	char arg_bitshift;
@@ -570,9 +581,8 @@ static struct elf_seg *find_vma_seg(struct elf_seg *segs, size_t seg_cnt, long o
 	return NULL;
 }
 
-static int parse_usdt_note(Elf *elf, const char *path, GElf_Nhdr *nhdr,
-			   const char *data, size_t name_off, size_t desc_off,
-			   struct usdt_note *usdt_note);
+static int parse_usdt_note(GElf_Nhdr *nhdr, const char *data, size_t name_off,
+			   size_t desc_off, struct usdt_note *usdt_note);
 
 static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, __u64 usdt_cookie);
 
@@ -626,7 +636,7 @@ static int collect_usdt_targets(struct usdt_manager *man, Elf *elf, const char *
 		struct elf_seg *seg = NULL;
 		void *tmp;
 
-		err = parse_usdt_note(elf, path, &nhdr, data->d_buf, name_off, desc_off, &note);
+		err = parse_usdt_note(&nhdr, data->d_buf, name_off, desc_off, &note);
 		if (err)
 			goto err_out;
 
@@ -1132,8 +1142,7 @@ err_out:
 /* Parse out USDT ELF note from '.note.stapsdt' section.
  * Logic inspired by perf's code.
  */
-static int parse_usdt_note(Elf *elf, const char *path, GElf_Nhdr *nhdr,
-			   const char *data, size_t name_off, size_t desc_off,
+static int parse_usdt_note(GElf_Nhdr *nhdr, const char *data, size_t name_off, size_t desc_off,
 			   struct usdt_note *note)
 {
 	const char *provider, *name, *args;
@@ -1283,11 +1292,51 @@ static int calc_pt_regs_off(const char *reg_name)
 
 static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg, int *arg_sz)
 {
-	char reg_name[16];
-	int len, reg_off;
-	long off;
+	char reg_name[16] = {0}, idx_reg_name[16] = {0};
+	int len, reg_off, idx_reg_off, scale = 1;
+	long off = 0;
+
+	if (sscanf(arg_str, " %d @ %ld ( %%%15[^,] , %%%15[^,] , %d ) %n",
+		   arg_sz, &off, reg_name, idx_reg_name, &scale, &len) == 5 ||
+		sscanf(arg_str, " %d @ ( %%%15[^,] , %%%15[^,] , %d ) %n",
+		       arg_sz, reg_name, idx_reg_name, &scale, &len) == 4 ||
+		sscanf(arg_str, " %d @ %ld ( %%%15[^,] , %%%15[^)] ) %n",
+		       arg_sz, &off, reg_name, idx_reg_name, &len) == 4 ||
+		sscanf(arg_str, " %d @ ( %%%15[^,] , %%%15[^)] ) %n",
+		       arg_sz, reg_name, idx_reg_name, &len) == 3
+		) {
+		/*
+		 * Scale Index Base case:
+		 * 1@-96(%rbp,%rax,8)
+		 * 1@(%rbp,%rax,8)
+		 * 1@-96(%rbp,%rax)
+		 * 1@(%rbp,%rax)
+		 */
+		arg->arg_type = USDT_ARG_SIB;
+		arg->val_off = off;
 
-	if (sscanf(arg_str, " %d @ %ld ( %%%15[^)] ) %n", arg_sz, &off, reg_name, &len) == 3) {
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+
+		idx_reg_off = calc_pt_regs_off(idx_reg_name);
+		if (idx_reg_off < 0)
+			return idx_reg_off;
+		arg->idx_reg_off = idx_reg_off;
+
+		/* validate scale factor and set fields directly */
+		switch (scale) {
+		case 1: arg->scale_bitshift = 0; break;
+		case 2: arg->scale_bitshift = 1; break;
+		case 4: arg->scale_bitshift = 2; break;
+		case 8: arg->scale_bitshift = 3; break;
+		default:
+			pr_warn("usdt: invalid SIB scale %d, expected 1, 2, 4, 8\n", scale);
+			return -EINVAL;
+		}
+	} else if (sscanf(arg_str, " %d @ %ld ( %%%15[^)] ) %n",
+				arg_sz, &off, reg_name, &len) == 3) {
 		/* Memory dereference case, e.g., -4@-20(%rbp) */
 		arg->arg_type = USDT_ARG_REG_DEREF;
 		arg->val_off = off;
@@ -1306,6 +1355,7 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
 	} 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;
+		/* register read has no memory offset */
 		arg->val_off = 0;
 
 		reg_off = calc_pt_regs_off(reg_name);