[PATCH v4 3/4] kallsyms: delta-compress lineinfo tables for ~2.7x size reduction

[Sasha Levin <sashal@kernel.org>]

Replace the flat uncompressed parallel arrays (lineinfo_addrs[],
lineinfo_file_ids[], lineinfo_lines[]) with a block-indexed,
delta-encoded, ULEB128 varint compressed format.

The sorted address array has small deltas between consecutive entries
(typically 1-50 bytes), file IDs have high locality (delta often 0,
same file), and line numbers change slowly.  Delta-encoding followed
by ULEB128 varint compression shrinks most values from 4 bytes to 1.

Entries are grouped into blocks of 64.  A small uncompressed block
index (first addr + byte offset per block) enables O(log(N/64)) binary
search, followed by sequential decode of at most 64 varints within the
matching block.  All decode state lives on the stack -- zero
allocations, still safe for NMI/panic context.

Measured on a defconfig+debug x86_64 build (3,017,154 entries, 4,822
source files, 47,144 blocks):

  Before (flat arrays):
    lineinfo_addrs[]    12,068,616 bytes (u32 x 3.0M)
    lineinfo_file_ids[]  6,034,308 bytes (u16 x 3.0M)
    lineinfo_lines[]    12,068,616 bytes (u32 x 3.0M)
    Total:              30,171,540 bytes (28.8 MiB, 10.0 bytes/entry)

  After (block-indexed delta + ULEB128):
    lineinfo_block_addrs[]    188,576 bytes (184 KiB)
    lineinfo_block_offsets[]  188,576 bytes (184 KiB)
    lineinfo_data[]        10,926,128 bytes (10.4 MiB)
    Total:                 11,303,280 bytes (10.8 MiB, 3.7 bytes/entry)

  Savings: 18.0 MiB (2.7x reduction)

Booted in QEMU and verified with SysRq-l that annotations still work:

  default_idle+0x9/0x10 (arch/x86/kernel/process.c:767)
  default_idle_call+0x6c/0xb0 (kernel/sched/idle.c:122)
  do_idle+0x335/0x490 (kernel/sched/idle.c:191)
  cpu_startup_entry+0x4e/0x60 (kernel/sched/idle.c:429)
  rest_init+0x1aa/0x1b0 (init/main.c:760)

Suggested-by: Juergen Gross <jgross@suse.com>
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 .../admin-guide/kallsyms-lineinfo.rst         |   7 +-
 include/linux/mod_lineinfo.h                  | 227 ++++++++++++++++--
 init/Kconfig                                  |   8 +-
 kernel/kallsyms.c                             |  46 ++--
 kernel/kallsyms_internal.h                    |   8 +-
 kernel/module/kallsyms.c                      |  85 +++----
 scripts/empty_lineinfo.S                      |  20 +-
 scripts/gen_lineinfo.c                        | 189 +++++++++------
 scripts/kallsyms.c                            |   7 +-
 9 files changed, 406 insertions(+), 191 deletions(-)

diff --git a/Documentation/admin-guide/kallsyms-lineinfo.rst b/Documentation/admin-guide/kallsyms-lineinfo.rst
index 5cae995eb118e..dd264830c8d5b 100644
--- a/Documentation/admin-guide/kallsyms-lineinfo.rst
+++ b/Documentation/admin-guide/kallsyms-lineinfo.rst
@@ -76,10 +76,11 @@ Memory Overhead
 ===============
 
 The vmlinux lineinfo tables are stored in ``.rodata`` and typically add
-approximately 44 MiB to the kernel image for a standard configuration
-(~4.6 million DWARF line entries, ~10 bytes per entry after deduplication).
+approximately 10-15 MiB to the kernel image for a standard configuration
+(~4.6 million DWARF line entries, ~2-3 bytes per entry after delta
+compression).
 
-Per-module lineinfo adds approximately 10 bytes per DWARF line entry to each
+Per-module lineinfo adds approximately 2-3 bytes per DWARF line entry to each
 ``.ko`` file.
 
 Known Limitations
diff --git a/include/linux/mod_lineinfo.h b/include/linux/mod_lineinfo.h
index d62e9608f0f82..364e5d81fe5bb 100644
--- a/include/linux/mod_lineinfo.h
+++ b/include/linux/mod_lineinfo.h
@@ -8,13 +8,23 @@
  *
  * Section layout (all values in target-native endianness):
  *
- *   struct mod_lineinfo_header     (16 bytes)
- *   u32 addrs[num_entries]         -- offsets from .text base, sorted
- *   u16 file_ids[num_entries]      -- parallel to addrs
- *   <2-byte pad if num_entries is odd>
- *   u32 lines[num_entries]         -- parallel to addrs
+ *   struct mod_lineinfo_header
+ *   u32 block_addrs[num_blocks]    -- first addr per block, for binary search
+ *   u32 block_offsets[num_blocks]  -- byte offset into compressed data stream
+ *   u8  data[data_size]            -- LEB128 delta-compressed entries
  *   u32 file_offsets[num_files]    -- byte offset into filenames[]
  *   char filenames[filenames_size] -- concatenated NUL-terminated strings
+ *
+ * Each sub-array is located by an explicit (offset, size) pair in the
+ * header, similar to a flattened devicetree.  This makes bounds checking
+ * straightforward: validate offset + size <= section_size for each array.
+ *
+ * Compressed stream format (per block of LINEINFO_BLOCK_ENTRIES entries):
+ *   Entry 0: file_id (ULEB128), line (ULEB128)
+ *            addr is in block_addrs[]
+ *   Entry 1..N: addr_delta (ULEB128),
+ *               file_id_delta (SLEB128),
+ *               line_delta (SLEB128)
  */
 #ifndef _LINUX_MOD_LINEINFO_H
 #define _LINUX_MOD_LINEINFO_H
@@ -25,44 +35,209 @@
 #include <stdint.h>
 typedef uint32_t u32;
 typedef uint16_t u16;
+typedef uint8_t  u8;
 #endif
 
+#define LINEINFO_BLOCK_ENTRIES 64
+
 struct mod_lineinfo_header {
 	u32 num_entries;
+	u32 num_blocks;
 	u32 num_files;
-	u32 filenames_size;	/* total bytes of concatenated filenames */
-	u32 reserved;		/* padding, must be 0 */
+	u32 blocks_offset;	/* offset to block_addrs[] from section start */
+	u32 blocks_size;	/* bytes: num_blocks * 2 * sizeof(u32) */
+	u32 data_offset;	/* offset to compressed stream */
+	u32 data_size;		/* bytes of compressed data */
+	u32 files_offset;	/* offset to file_offsets[] */
+	u32 files_size;		/* bytes: num_files * sizeof(u32) */
+	u32 filenames_offset;
+	u32 filenames_size;
+	u32 reserved;		/* must be 0 */
 };
 
-/* Offset helpers: compute byte offset from start of section to each array */
+/*
+ * Descriptor for a lineinfo table, used by the shared lookup function.
+ * Callers populate this from either linker globals (vmlinux) or a
+ * validated mod_lineinfo_header (modules).
+ */
+struct lineinfo_table {
+	const u32 *blk_addrs;
+	const u32 *blk_offsets;
+	const u8  *data;
+	u32 data_size;
+	const u32 *file_offsets;
+	const char *filenames;
+	u32 num_entries;
+	u32 num_blocks;
+	u32 num_files;
+	u32 filenames_size;
+};
 
-static inline u32 mod_lineinfo_addrs_off(void)
+/*
+ * Read a ULEB128 varint from a byte stream.
+ * Returns the decoded value and advances *pos past the encoded bytes.
+ * If *pos would exceed 'end', returns 0 and sets *pos = end (safe for
+ * NMI/panic context: no crash, just a missed annotation).
+ */
+static inline u32 lineinfo_read_uleb128(const u8 *data, u32 *pos, u32 end)
 {
-	return sizeof(struct mod_lineinfo_header);
-}
+	u32 result = 0;
+	unsigned int shift = 0;
 
-static inline u32 mod_lineinfo_file_ids_off(u32 num_entries)
-{
-	return mod_lineinfo_addrs_off() + num_entries * sizeof(u32);
+	while (*pos < end) {
+		u8 byte = data[*pos];
+		(*pos)++;
+		result |= (u32)(byte & 0x7f) << shift;
+		if (!(byte & 0x80))
+			return result;
+		shift += 7;
+		if (shift >= 32) {
+			/* Malformed: skip remaining continuation bytes */
+			while (*pos < end && (data[*pos] & 0x80))
+				(*pos)++;
+			if (*pos < end)
+				(*pos)++;
+			return result;
+		}
+	}
+	return result;
 }
 
-static inline u32 mod_lineinfo_lines_off(u32 num_entries)
+/* Read an SLEB128 varint. Same safety guarantees as above. */
+static inline int32_t lineinfo_read_sleb128(const u8 *data, u32 *pos, u32 end)
 {
-	/* u16 file_ids[] may need 2-byte padding to align lines[] to 4 bytes */
-	u32 off = mod_lineinfo_file_ids_off(num_entries) +
-		  num_entries * sizeof(u16);
-	return (off + 3) & ~3u;
-}
+	int32_t result = 0;
+	unsigned int shift = 0;
+	u8 byte = 0;
 
-static inline u32 mod_lineinfo_file_offsets_off(u32 num_entries)
-{
-	return mod_lineinfo_lines_off(num_entries) + num_entries * sizeof(u32);
+	while (*pos < end) {
+		byte = data[*pos];
+		(*pos)++;
+		result |= (int32_t)(byte & 0x7f) << shift;
+		shift += 7;
+		if (!(byte & 0x80))
+			break;
+		if (shift >= 32) {
+			while (*pos < end && (data[*pos] & 0x80))
+				(*pos)++;
+			if (*pos < end)
+				(*pos)++;
+			return result;
+		}
+	}
+
+	/* Sign-extend if the high bit of the last byte was set */
+	if (shift < 32 && (byte & 0x40))
+		result |= -(1 << shift);
+
+	return result;
 }
 
-static inline u32 mod_lineinfo_filenames_off(u32 num_entries, u32 num_files)
+/*
+ * Search a lineinfo table for the source file and line corresponding to a
+ * given offset (from _text for vmlinux, from .text base for modules).
+ *
+ * Safe for NMI and panic context: no locks, no allocations, all state on stack.
+ * Returns true and sets @file and @line on success; false on any failure.
+ */
+static inline bool lineinfo_search(const struct lineinfo_table *tbl,
+				   unsigned int offset,
+				   const char **file, unsigned int *line)
 {
-	return mod_lineinfo_file_offsets_off(num_entries) +
-	       num_files * sizeof(u32);
+	unsigned int low, high, mid, block;
+	unsigned int cur_addr, cur_file_id, cur_line;
+	unsigned int best_file_id = 0, best_line = 0;
+	unsigned int block_entries, data_end;
+	bool found = false;
+	u32 pos;
+
+	if (!tbl->num_entries || !tbl->num_blocks)
+		return false;
+
+	/* Binary search on blk_addrs[] to find the right block */
+	low = 0;
+	high = tbl->num_blocks;
+	while (low < high) {
+		mid = low + (high - low) / 2;
+		if (tbl->blk_addrs[mid] <= offset)
+			low = mid + 1;
+		else
+			high = mid;
+	}
+
+	if (low == 0)
+		return false;
+	block = low - 1;
+
+	/* How many entries in this block? */
+	block_entries = LINEINFO_BLOCK_ENTRIES;
+	if (block == tbl->num_blocks - 1) {
+		unsigned int remaining = tbl->num_entries -
+					block * LINEINFO_BLOCK_ENTRIES;
+
+		if (remaining < block_entries)
+			block_entries = remaining;
+	}
+
+	/* Determine end of this block's data in the compressed stream */
+	if (block + 1 < tbl->num_blocks)
+		data_end = tbl->blk_offsets[block + 1];
+	else
+		data_end = tbl->data_size;
+
+	/* Clamp data_end to actual data size */
+	if (data_end > tbl->data_size)
+		data_end = tbl->data_size;
+
+	/* Decode entry 0: addr from blk_addrs, file_id and line from stream */
+	pos = tbl->blk_offsets[block];
+	if (pos >= data_end)
+		return false;
+
+	cur_addr = tbl->blk_addrs[block];
+	cur_file_id = lineinfo_read_uleb128(tbl->data, &pos, data_end);
+	cur_line = lineinfo_read_uleb128(tbl->data, &pos, data_end);
+
+	/* Check entry 0 */
+	if (cur_addr <= offset) {
+		best_file_id = cur_file_id;
+		best_line = cur_line;
+		found = true;
+	}
+
+	/* Decode entries 1..N */
+	for (unsigned int i = 1; i < block_entries; i++) {
+		unsigned int addr_delta;
+		int32_t file_delta, line_delta;
+
+		addr_delta = lineinfo_read_uleb128(tbl->data, &pos, data_end);
+		file_delta = lineinfo_read_sleb128(tbl->data, &pos, data_end);
+		line_delta = lineinfo_read_sleb128(tbl->data, &pos, data_end);
+
+		cur_addr += addr_delta;
+		cur_file_id = (unsigned int)((int32_t)cur_file_id + file_delta);
+		cur_line = (unsigned int)((int32_t)cur_line + line_delta);
+
+		if (cur_addr > offset)
+			break;
+
+		best_file_id = cur_file_id;
+		best_line = cur_line;
+		found = true;
+	}
+
+	if (!found)
+		return false;
+
+	if (best_file_id >= tbl->num_files)
+		return false;
+
+	if (tbl->file_offsets[best_file_id] >= tbl->filenames_size)
+		return false;
+
+	*file = &tbl->filenames[tbl->file_offsets[best_file_id]];
+	*line = best_line;
+	return true;
 }
 
 #endif /* _LINUX_MOD_LINEINFO_H */
diff --git a/init/Kconfig b/init/Kconfig
index bf53275bc405a..6e3795b3dbd62 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2065,8 +2065,9 @@ config KALLSYMS_LINEINFO
 	    anon_vma_clone+0x2ed/0xcf0 (mm/rmap.c:412)
 
 	  This requires elfutils (libdw-dev/elfutils-devel) on the build host.
-	  Adds approximately 44MB to a typical kernel image (10 bytes per
-	  DWARF line-table entry, ~4.6M entries for a typical config).
+	  Adds approximately 10-15MB to a typical kernel image (~2-3 bytes
+	  per entry after delta compression, ~4.6M entries for a typical
+	  config).
 
 	  If unsure, say N.
 
@@ -2079,7 +2080,8 @@ config KALLSYMS_LINEINFO_MODULES
 	  so stack traces from module code include (file.c:123) annotations.
 
 	  Requires elfutils (libdw-dev/elfutils-devel) on the build host.
-	  Increases .ko sizes by approximately 10 bytes per DWARF line entry.
+	  Increases .ko sizes by approximately 2-3 bytes per DWARF line
+	  entry after delta compression.
 
 	  If unsure, say N.
 
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 9df92b0fd9041..76e30cac3a277 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -467,13 +467,16 @@ static int append_buildid(char *buffer,   const char *modname,
 
 #endif /* CONFIG_STACKTRACE_BUILD_ID */
 
+#include <linux/mod_lineinfo.h>
+
 bool kallsyms_lookup_lineinfo(unsigned long addr,
 			      const char **file, unsigned int *line)
 {
+	struct lineinfo_table tbl;
 	unsigned long long raw_offset;
-	unsigned int offset, low, high, mid, file_id;
 
-	if (!IS_ENABLED(CONFIG_KALLSYMS_LINEINFO) || !lineinfo_num_entries)
+	if (!IS_ENABLED(CONFIG_KALLSYMS_LINEINFO) ||
+	    !lineinfo_num_entries || !lineinfo_num_blocks)
 		return false;
 
 	/* Compute offset from _text */
@@ -483,34 +486,19 @@ bool kallsyms_lookup_lineinfo(unsigned long addr,
 	raw_offset = addr - (unsigned long)_text;
 	if (raw_offset > UINT_MAX)
 		return false;
-	offset = (unsigned int)raw_offset;
-
-	/* Binary search for largest entry <= offset */
-	low = 0;
-	high = lineinfo_num_entries;
-	while (low < high) {
-		mid = low + (high - low) / 2;
-		if (lineinfo_addrs[mid] <= offset)
-			low = mid + 1;
-		else
-			high = mid;
-	}
-
-	if (low == 0)
-		return false;
-	low--;
-
-	file_id = lineinfo_file_ids[low];
-	*line = lineinfo_lines[low];
-
-	if (file_id >= lineinfo_num_files)
-		return false;
-
-	if (lineinfo_file_offsets[file_id] >= lineinfo_filenames_size)
-		return false;
 
-	*file = &lineinfo_filenames[lineinfo_file_offsets[file_id]];
-	return true;
+	tbl.blk_addrs	= lineinfo_block_addrs;
+	tbl.blk_offsets	= lineinfo_block_offsets;
+	tbl.data	= lineinfo_data;
+	tbl.data_size	= lineinfo_data_size;
+	tbl.file_offsets = lineinfo_file_offsets;
+	tbl.filenames	= lineinfo_filenames;
+	tbl.num_entries	= lineinfo_num_entries;
+	tbl.num_blocks	= lineinfo_num_blocks;
+	tbl.num_files	= lineinfo_num_files;
+	tbl.filenames_size = lineinfo_filenames_size;
+
+	return lineinfo_search(&tbl, (unsigned int)raw_offset, file, line);
 }
 
 /* Look up a kernel symbol and return it in a text buffer. */
diff --git a/kernel/kallsyms_internal.h b/kernel/kallsyms_internal.h
index d7374ce444d81..ffe4c658067ec 100644
--- a/kernel/kallsyms_internal.h
+++ b/kernel/kallsyms_internal.h
@@ -16,10 +16,12 @@ extern const unsigned int kallsyms_markers[];
 extern const u8 kallsyms_seqs_of_names[];
 
 extern const u32 lineinfo_num_entries;
-extern const u32 lineinfo_addrs[];
-extern const u16 lineinfo_file_ids[];
-extern const u32 lineinfo_lines[];
 extern const u32 lineinfo_num_files;
+extern const u32 lineinfo_num_blocks;
+extern const u32 lineinfo_block_addrs[];
+extern const u32 lineinfo_block_offsets[];
+extern const u32 lineinfo_data_size;
+extern const u8  lineinfo_data[];
 extern const u32 lineinfo_file_offsets[];
 extern const u32 lineinfo_filenames_size;
 extern const char lineinfo_filenames[];
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 5b46293e957ab..8715a923ba536 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -509,16 +509,11 @@ bool module_lookup_lineinfo(struct module *mod, unsigned long addr,
 			    const char **file, unsigned int *line)
 {
 	const struct mod_lineinfo_header *hdr;
+	struct lineinfo_table tbl;
 	const void *base;
-	const u32 *addrs, *lines, *file_offsets;
-	const u16 *file_ids;
-	const char *filenames;
-	u32 num_entries, num_files, filenames_size;
+	u32 section_size;
 	unsigned long text_base;
-	unsigned int offset;
 	unsigned long long raw_offset;
-	unsigned int low, high, mid;
-	u16 file_id;
 
 	if (!IS_ENABLED(CONFIG_KALLSYMS_LINEINFO_MODULES))
 		return false;
@@ -527,61 +522,55 @@ bool module_lookup_lineinfo(struct module *mod, unsigned long addr,
 	if (!base)
 		return false;
 
-	if (mod->lineinfo_data_size < sizeof(*hdr))
+	section_size = mod->lineinfo_data_size;
+	if (section_size < sizeof(*hdr))
 		return false;
 
 	hdr = base;
-	num_entries = hdr->num_entries;
-	num_files = hdr->num_files;
-	filenames_size = hdr->filenames_size;
 
-	if (num_entries == 0)
+	if (hdr->num_entries == 0 || hdr->num_blocks == 0)
 		return false;
 
-	/* Validate section is large enough for all arrays */
-	if (mod->lineinfo_data_size <
-	    mod_lineinfo_filenames_off(num_entries, num_files) + filenames_size)
+	/* Validate each sub-array fits within the section */
+	if (hdr->blocks_offset + hdr->blocks_size > section_size)
 		return false;
-
-	addrs = base + mod_lineinfo_addrs_off();
-	file_ids = base + mod_lineinfo_file_ids_off(num_entries);
-	lines = base + mod_lineinfo_lines_off(num_entries);
-	file_offsets = base + mod_lineinfo_file_offsets_off(num_entries);
-	filenames = base + mod_lineinfo_filenames_off(num_entries, num_files);
-
-	/* Compute offset from module .text base */
-	text_base = (unsigned long)mod->mem[MOD_TEXT].base;
-	if (addr < text_base)
+	if (hdr->data_offset + hdr->data_size > section_size)
 		return false;
-
-	raw_offset = addr - text_base;
-	if (raw_offset > UINT_MAX)
+	if (hdr->files_offset + hdr->files_size > section_size)
+		return false;
+	if (hdr->filenames_offset + hdr->filenames_size > section_size)
 		return false;
-	offset = (unsigned int)raw_offset;
-
-	/* Binary search for largest entry <= offset */
-	low = 0;
-	high = num_entries;
-	while (low < high) {
-		mid = low + (high - low) / 2;
-		if (addrs[mid] <= offset)
-			low = mid + 1;
-		else
-			high = mid;
-	}
 
-	if (low == 0)
+	/* Validate array sizes match declared counts */
+	if (hdr->blocks_size < hdr->num_blocks * 2 * sizeof(u32))
+		return false;
+	if (hdr->files_size < hdr->num_files * sizeof(u32))
 		return false;
-	low--;
 
-	file_id = file_ids[low];
-	if (file_id >= num_files)
+	/*
+	 * Compute offset from module .text base.
+	 * NOTE: This assumes .text is at the start of the MOD_TEXT segment.
+	 * A proper fix would use ELF relocations to reference .text directly.
+	 */
+	text_base = (unsigned long)mod->mem[MOD_TEXT].base;
+	if (addr < text_base)
 		return false;
 
-	if (file_offsets[file_id] >= filenames_size)
+	raw_offset = addr - text_base;
+	if (raw_offset > U32_MAX)
 		return false;
 
-	*file = &filenames[file_offsets[file_id]];
-	*line = lines[low];
-	return true;
+	tbl.blk_addrs	= base + hdr->blocks_offset;
+	tbl.blk_offsets	= base + hdr->blocks_offset +
+			  hdr->num_blocks * sizeof(u32);
+	tbl.data	= base + hdr->data_offset;
+	tbl.data_size	= hdr->data_size;
+	tbl.file_offsets = base + hdr->files_offset;
+	tbl.filenames	= base + hdr->filenames_offset;
+	tbl.num_entries	= hdr->num_entries;
+	tbl.num_blocks	= hdr->num_blocks;
+	tbl.num_files	= hdr->num_files;
+	tbl.filenames_size = hdr->filenames_size;
+
+	return lineinfo_search(&tbl, (unsigned int)raw_offset, file, line);
 }
diff --git a/scripts/empty_lineinfo.S b/scripts/empty_lineinfo.S
index e058c41137123..edd5b1092f050 100644
--- a/scripts/empty_lineinfo.S
+++ b/scripts/empty_lineinfo.S
@@ -14,12 +14,20 @@ lineinfo_num_entries:
 	.balign 4
 lineinfo_num_files:
 	.long 0
-	.globl lineinfo_addrs
-lineinfo_addrs:
-	.globl lineinfo_file_ids
-lineinfo_file_ids:
-	.globl lineinfo_lines
-lineinfo_lines:
+	.globl lineinfo_num_blocks
+	.balign 4
+lineinfo_num_blocks:
+	.long 0
+	.globl lineinfo_block_addrs
+lineinfo_block_addrs:
+	.globl lineinfo_block_offsets
+lineinfo_block_offsets:
+	.globl lineinfo_data_size
+	.balign 4
+lineinfo_data_size:
+	.long 0
+	.globl lineinfo_data
+lineinfo_data:
 	.globl lineinfo_file_offsets
 lineinfo_file_offsets:
 	.globl lineinfo_filenames_size
diff --git a/scripts/gen_lineinfo.c b/scripts/gen_lineinfo.c
index 7d06701549345..45b1c1081164d 100644
--- a/scripts/gen_lineinfo.c
+++ b/scripts/gen_lineinfo.c
@@ -548,6 +548,35 @@ static void deduplicate(void)
 	num_entries = j + 1;
 }
 
+/*
+ * Emit the LEB128 delta-compressed data stream for one block.
+ * Uses .uleb128/.sleb128 assembler directives for encoding.
+ */
+static void emit_block_data(unsigned int block)
+{
+	unsigned int base = block * LINEINFO_BLOCK_ENTRIES;
+	unsigned int count = num_entries - base;
+
+	if (count > LINEINFO_BLOCK_ENTRIES)
+		count = LINEINFO_BLOCK_ENTRIES;
+
+	/* Entry 0: file_id, line (both unsigned) */
+	printf("\t.uleb128 %u\n", entries[base].file_id);
+	printf("\t.uleb128 %u\n", entries[base].line);
+
+	/* Entries 1..N: addr_delta (unsigned), file/line deltas (signed) */
+	for (unsigned int i = 1; i < count; i++) {
+		unsigned int idx = base + i;
+
+		printf("\t.uleb128 %u\n",
+		       entries[idx].offset - entries[idx - 1].offset);
+		printf("\t.sleb128 %d\n",
+		       (int)entries[idx].file_id - (int)entries[idx - 1].file_id);
+		printf("\t.sleb128 %d\n",
+		       (int)entries[idx].line - (int)entries[idx - 1].line);
+	}
+}
+
 static void compute_file_offsets(void)
 {
 	unsigned int offset = 0;
@@ -571,6 +600,11 @@ static void print_escaped_asciz(const char *s)
 
 static void output_assembly(void)
 {
+	unsigned int num_blocks;
+
+	num_blocks = num_entries ?
+		(num_entries + LINEINFO_BLOCK_ENTRIES - 1) / LINEINFO_BLOCK_ENTRIES : 0;
+
 	printf("/* SPDX-License-Identifier: GPL-2.0 */\n");
 	printf("/*\n");
 	printf(" * Automatically generated by scripts/gen_lineinfo\n");
@@ -591,29 +625,40 @@ static void output_assembly(void)
 	printf("lineinfo_num_files:\n");
 	printf("\t.long %u\n\n", num_files);
 
-	/* Sorted address offsets from _text */
-	printf("\t.globl lineinfo_addrs\n");
+	/* Number of blocks */
+	printf("\t.globl lineinfo_num_blocks\n");
+	printf("\t.balign 4\n");
+	printf("lineinfo_num_blocks:\n");
+	printf("\t.long %u\n\n", num_blocks);
+
+	/* Block first-addresses for binary search */
+	printf("\t.globl lineinfo_block_addrs\n");
 	printf("\t.balign 4\n");
-	printf("lineinfo_addrs:\n");
-	for (unsigned int i = 0; i < num_entries; i++)
-		printf("\t.long 0x%x\n", entries[i].offset);
-	printf("\n");
-
-	/* File IDs, parallel to addrs (u16 -- supports up to 65535 files) */
-	printf("\t.globl lineinfo_file_ids\n");
-	printf("\t.balign 2\n");
-	printf("lineinfo_file_ids:\n");
-	for (unsigned int i = 0; i < num_entries; i++)
-		printf("\t.short %u\n", entries[i].file_id);
-	printf("\n");
-
-	/* Line numbers, parallel to addrs */
-	printf("\t.globl lineinfo_lines\n");
+	printf("lineinfo_block_addrs:\n");
+	for (unsigned int i = 0; i < num_blocks; i++)
+		printf("\t.long 0x%x\n", entries[i * LINEINFO_BLOCK_ENTRIES].offset);
+
+	/* Block byte offsets into compressed stream */
+	printf("\t.globl lineinfo_block_offsets\n");
 	printf("\t.balign 4\n");
-	printf("lineinfo_lines:\n");
-	for (unsigned int i = 0; i < num_entries; i++)
-		printf("\t.long %u\n", entries[i].line);
-	printf("\n");
+	printf("lineinfo_block_offsets:\n");
+	for (unsigned int i = 0; i < num_blocks; i++)
+		printf("\t.long .Lblock_%u - lineinfo_data\n", i);
+
+	/* Compressed data size */
+	printf("\t.globl lineinfo_data_size\n");
+	printf("\t.balign 4\n");
+	printf("lineinfo_data_size:\n");
+	printf("\t.long .Ldata_end - lineinfo_data\n\n");
+
+	/* Compressed data stream */
+	printf("\t.globl lineinfo_data\n");
+	printf("lineinfo_data:\n");
+	for (unsigned int i = 0; i < num_blocks; i++) {
+		printf(".Lblock_%u:\n", i);
+		emit_block_data(i);
+	}
+	printf(".Ldata_end:\n\n");
 
 	/* File string offset table */
 	printf("\t.globl lineinfo_file_offsets\n");
@@ -621,34 +666,27 @@ static void output_assembly(void)
 	printf("lineinfo_file_offsets:\n");
 	for (unsigned int i = 0; i < num_files; i++)
 		printf("\t.long %u\n", files[i].str_offset);
-	printf("\n");
 
 	/* Filenames size */
-	{
-		unsigned int fsize = 0;
-
-		for (unsigned int i = 0; i < num_files; i++)
-			fsize += strlen(files[i].name) + 1;
-		printf("\t.globl lineinfo_filenames_size\n");
-		printf("\t.balign 4\n");
-		printf("lineinfo_filenames_size:\n");
-		printf("\t.long %u\n\n", fsize);
-	}
+	printf("\t.globl lineinfo_filenames_size\n");
+	printf("\t.balign 4\n");
+	printf("lineinfo_filenames_size:\n");
+	printf("\t.long .Lfilenames_end - lineinfo_filenames\n\n");
 
 	/* Concatenated NUL-terminated filenames */
 	printf("\t.globl lineinfo_filenames\n");
 	printf("lineinfo_filenames:\n");
 	for (unsigned int i = 0; i < num_files; i++)
 		print_escaped_asciz(files[i].name);
-	printf("\n");
+	printf(".Lfilenames_end:\n");
 }
 
 static void output_module_assembly(void)
 {
-	unsigned int filenames_size = 0;
+	unsigned int num_blocks;
 
-	for (unsigned int i = 0; i < num_files; i++)
-		filenames_size += strlen(files[i].name) + 1;
+	num_blocks = num_entries ?
+		(num_entries + LINEINFO_BLOCK_ENTRIES - 1) / LINEINFO_BLOCK_ENTRIES : 0;
 
 	printf("/* SPDX-License-Identifier: GPL-2.0 */\n");
 	printf("/*\n");
@@ -658,46 +696,56 @@ static void output_module_assembly(void)
 
 	printf("\t.section .mod_lineinfo, \"a\"\n\n");
 
-	/* Header: num_entries, num_files, filenames_size, reserved */
+	/*
+	 * Header -- offsets and sizes are assembler expressions so the
+	 * layout is self-describing without manual C arithmetic.
+	 */
+	printf(".Lhdr:\n");
 	printf("\t.balign 4\n");
-	printf("\t.long %u\n", num_entries);
-	printf("\t.long %u\n", num_files);
-	printf("\t.long %u\n", filenames_size);
-	printf("\t.long 0\n\n");
-
-	/* addrs[] */
-	for (unsigned int i = 0; i < num_entries; i++)
-		printf("\t.long 0x%x\n", entries[i].offset);
-	if (num_entries)
-		printf("\n");
-
-	/* file_ids[] */
-	for (unsigned int i = 0; i < num_entries; i++)
-		printf("\t.short %u\n", entries[i].file_id);
-
-	/* Padding to align lines[] to 4 bytes */
-	if (num_entries & 1)
-		printf("\t.short 0\n");
-	if (num_entries)
-		printf("\n");
-
-	/* lines[] */
-	for (unsigned int i = 0; i < num_entries; i++)
-		printf("\t.long %u\n", entries[i].line);
-	if (num_entries)
-		printf("\n");
+	printf("\t.long %u\t\t\t\t/* num_entries */\n", num_entries);
+	printf("\t.long %u\t\t\t\t/* num_blocks */\n", num_blocks);
+	printf("\t.long %u\t\t\t\t/* num_files */\n", num_files);
+	printf("\t.long .Lblk_addrs - .Lhdr\t\t/* blocks_offset */\n");
+	printf("\t.long .Lblk_offsets_end - .Lblk_addrs\t/* blocks_size */\n");
+	printf("\t.long .Ldata - .Lhdr\t\t\t/* data_offset */\n");
+	printf("\t.long .Ldata_end - .Ldata\t\t/* data_size */\n");
+	printf("\t.long .Lfile_offsets - .Lhdr\t\t/* files_offset */\n");
+	printf("\t.long .Lfile_offsets_end - .Lfile_offsets /* files_size */\n");
+	printf("\t.long .Lfilenames - .Lhdr\t\t/* filenames_offset */\n");
+	printf("\t.long .Lfilenames_end - .Lfilenames\t/* filenames_size */\n");
+	printf("\t.long 0\t\t\t\t\t/* reserved */\n\n");
+
+	/* block_addrs[] */
+	printf(".Lblk_addrs:\n");
+	for (unsigned int i = 0; i < num_blocks; i++)
+		printf("\t.long 0x%x\n", entries[i * LINEINFO_BLOCK_ENTRIES].offset);
+
+	/* block_offsets[] */
+	printf(".Lblk_offsets:\n");
+	for (unsigned int i = 0; i < num_blocks; i++)
+		printf("\t.long .Lblock_%u - .Ldata\n", i);
+	printf(".Lblk_offsets_end:\n\n");
+
+	/* compressed data stream */
+	printf(".Ldata:\n");
+	for (unsigned int i = 0; i < num_blocks; i++) {
+		printf(".Lblock_%u:\n", i);
+		emit_block_data(i);
+	}
+	printf(".Ldata_end:\n");
 
 	/* file_offsets[] */
+	printf("\t.balign 4\n");
+	printf(".Lfile_offsets:\n");
 	for (unsigned int i = 0; i < num_files; i++)
 		printf("\t.long %u\n", files[i].str_offset);
-	if (num_files)
-		printf("\n");
+	printf(".Lfile_offsets_end:\n\n");
 
 	/* filenames[] */
+	printf(".Lfilenames:\n");
 	for (unsigned int i = 0; i < num_files; i++)
 		print_escaped_asciz(files[i].name);
-	if (num_files)
-		printf("\n");
+	printf(".Lfilenames_end:\n");
 }
 
 int main(int argc, char *argv[])
@@ -777,8 +825,10 @@ int main(int argc, char *argv[])
 	deduplicate();
 	compute_file_offsets();
 
-	fprintf(stderr, "lineinfo: %u entries, %u files\n",
-		num_entries, num_files);
+	fprintf(stderr, "lineinfo: %u entries, %u files, %u blocks\n",
+		num_entries, num_files,
+		num_entries ?
+		(num_entries + LINEINFO_BLOCK_ENTRIES - 1) / LINEINFO_BLOCK_ENTRIES : 0);
 
 	if (module_mode)
 		output_module_assembly();
@@ -794,6 +844,5 @@ int main(int argc, char *argv[])
 	for (unsigned int i = 0; i < num_files; i++)
 		free(files[i].name);
 	free(files);
-
 	return 0;
 }
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 42662c4fbc6c9..94fbdad3df7c6 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -80,11 +80,12 @@ static bool is_ignored_symbol(const char *name, char type)
 {
 	/* Ignore lineinfo symbols for kallsyms pass stability */
 	static const char * const lineinfo_syms[] = {
-		"lineinfo_addrs",
-		"lineinfo_file_ids",
+		"lineinfo_block_addrs",
+		"lineinfo_block_offsets",
+		"lineinfo_data",
 		"lineinfo_file_offsets",
 		"lineinfo_filenames",
-		"lineinfo_lines",
+		"lineinfo_num_blocks",
 		"lineinfo_num_entries",
 		"lineinfo_num_files",
 	};
-- 
2.51.0