Re: [PATCH 01/17] kallsyms: support big kernel symbols (2-byte lengths)
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-07-04 21:34:16
Also in:
linux-kbuild, lkml, rust-for-linux
Subsystem:
the rest · Maintainer:
Linus Torvalds
On Sun, Jul 04, 2021 at 11:17:50PM +0200, Miguel Ojeda wrote:
On Sun, Jul 4, 2021 at 11:05 PM Matthew Wilcox [off-list ref] wrote:quoted
What happened to my suggestion from last time of encoding symbols < 128 as 0-127 and symbols larger than that as (data[0] - 128) * 256 + data[1]) ?Nothing, sorry, we focused on other parts (e.g. the allocation panics) during this iteration. I can take a look for v2.
Here's what I have. Build testing now.
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index c851ca0ed357..0d45a6e5fdc3 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c@@ -67,6 +67,14 @@ static unsigned int kallsyms_expand_symbol(unsigned int off, len = *data; data++; + /* lengths larger than 128 are encoded as two bytes */ + if (len >= 128) { + len -= 128; + len *= 256; + len += *data; + data++; + } + /* * Update the offset to return the offset for the next symbol on * the compressed stream.
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 54ad86d13784..701566e01a1d 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c@@ -467,10 +467,16 @@ static void write_src(void) output_label("kallsyms_names"); off = 0; for (i = 0; i < table_cnt; i++) { + int len = table[i]->len; if ((i & 0xFF) == 0) markers[i >> 8] = off; - printf("\t.byte 0x%02x", table[i]->len); + if (len >= 128) { + printf("\t.byte 0x%02x\n", len / 256 + 128); + len %= 256; + off++; + } + printf("\t.byte 0x%02x", len); for (k = 0; k < table[i]->len; k++) printf(", 0x%02x", table[i]->sym[k]); printf("\n");