lkml.org 
[lkml]   [2014]   [Feb]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4/6] kbuild: Support padding in kallsyms tables
Date
Add support for padding the variable length tables in kallsyms.
This adds a new --pad=XXX option to kallsyms to specify the table lengths,
and another option --pad-file=X to write the table lengths to a file.
Then when a table is shorter than the padding add the necessary padding
at the end.

This allows to replace an existing symbol table later with a different
one that may differ slightly.

Add 5% slack for now in case the prediction is too small
(can happen with LTO)

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
scripts/kallsyms.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 90 insertions(+), 3 deletions(-)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index d79027e..c874304 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -23,6 +23,13 @@
#include <string.h>
#include <ctype.h>

+/*
+ * The ratio to increase the padding, by how much the final kallsyms
+ * can be larger. This is for symbols that are not visible before
+ * final linking.
+ */
+#define PAD_RATIO 20 /* 1/x = ~5% */
+
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
#endif
@@ -41,6 +48,14 @@ struct text_range {
unsigned long long start, end;
};

+enum pads {
+ PAD_OFF,
+ PAD_NAMES,
+ PAD_MARKERS,
+ PAD_TOKTAB,
+ NUM_PAD
+};
+
static unsigned long long _text;
static struct text_range text_ranges[] = {
{ "_stext", "_etext" },
@@ -69,6 +84,7 @@ static void usage(void)
fprintf(stderr, "Usage: kallsyms [--all-symbols] "
"[--symbol-prefix=<prefix char>] "
"[--page-offset=<CONFIG_PAGE_OFFSET>] "
+ "[--pad=A,B,C] [--pad-file=name] "
"< in.map > out.S\n");
exit(1);
}
@@ -303,7 +319,14 @@ static int expand_symbol(unsigned char *data, int len, char *result)
return total;
}

-static void write_src(void)
+static void bad_padding(char *msg, int diff)
+{
+ fprintf(stderr, "kallsyms: %s padding too short: %d missing\n",
+ msg, diff);
+ exit(EXIT_FAILURE);
+}
+
+static void write_src(int *pad, int *opad)
{
unsigned int i, k, off;
unsigned int best_idx[256];
@@ -335,6 +358,16 @@ static void write_src(void)
for (i = 0; i < table_cnt; i++) {
printf("\tPTR\t%#llx\n", table[i].addr - _text);
}
+ if (pad) {
+ if (i > pad[PAD_OFF])
+ bad_padding("address pointers", i - pad[PAD_OFF]);
+ for (; i < pad[PAD_OFF]; i++)
+ printf("\tPTR\t0\n");
+ } else {
+ for (i = 0; i < table_cnt / PAD_RATIO; i++)
+ printf("\tPTR\t0\n");
+ opad[PAD_OFF] = table_cnt + table_cnt/PAD_RATIO;
+ }
printf("\n");

output_label("kallsyms_num_syms");
@@ -363,11 +396,31 @@ static void write_src(void)

off += table[i].len + 1;
}
+ if (pad) {
+ if (off > pad[PAD_NAMES])
+ bad_padding("name table", off - pad[PAD_NAMES]);
+ if (off < pad[PAD_NAMES])
+ printf("\t.fill %d,1,0\n", pad[PAD_NAMES] - off);
+ } else {
+ printf("\t.fill %d,1,0\n", off/PAD_RATIO);
+ off += off/PAD_RATIO;
+ opad[PAD_NAMES] = off;
+ }
printf("\n");

output_label("kallsyms_markers");
for (i = 0; i < ((table_cnt + 255) >> 8); i++)
printf("\tPTR\t%d\n", markers[i]);
+ if (pad) {
+ if (i > pad[PAD_MARKERS])
+ bad_padding("markers", i - pad[PAD_MARKERS]);
+ for (; i < pad[PAD_MARKERS]; i++)
+ printf("\tPTR\t0\n");
+ } else {
+ for (k = 0; k < i/PAD_RATIO; k++)
+ printf("\tPTR\t0\n");
+ opad[PAD_MARKERS] = i + i/PAD_RATIO;
+ }
printf("\n");

free(markers);
@@ -380,6 +433,16 @@ static void write_src(void)
printf("\t.asciz\t\"%s\"\n", buf);
off += strlen(buf) + 1;
}
+ if (pad) {
+ if (off > pad[PAD_TOKTAB])
+ bad_padding("token table", off - pad[PAD_TOKTAB]);
+ if (off < pad[PAD_TOKTAB])
+ printf("\t.fill %d,1,0\n", pad[PAD_TOKTAB] - off);
+ } else {
+ printf("\t.fill %d,1,0\n", off/PAD_RATIO);
+ off += off/PAD_RATIO;
+ opad[PAD_TOKTAB] = off;
+ }
printf("\n");

output_label("kallsyms_token_index");
@@ -647,6 +710,10 @@ static void sort_symbols(void)

int main(int argc, char **argv)
{
+ int inpad[NUM_PAD], opad[NUM_PAD];
+ int *inpadp = NULL;
+ FILE *opadf = NULL;
+
if (argc >= 2) {
int i;
for (i = 1; i < argc; i++) {
@@ -661,6 +728,22 @@ int main(int argc, char **argv)
} else if (strncmp(argv[i], "--page-offset=", 14) == 0) {
const char *p = &argv[i][14];
kernel_start_addr = strtoull(p, NULL, 16);
+ } else if (strncmp(argv[i], "--pad=", 6) == 0) {
+ inpadp = inpad;
+ if (sscanf(argv[i] + 6, "%d,%d,%d,%d",
+ inpad + 0,
+ inpad + 1,
+ inpad + 2,
+ inpad + 3) != NUM_PAD) {
+ fprintf(stderr, "Bad pad list\n");
+ exit(EXIT_FAILURE);
+ }
+ } else if (strncmp(argv[i], "--pad-file=", 11) == 0) {
+ opadf = fopen(argv[i] + 11, "w");
+ if (!opadf) {
+ fprintf(stderr, "Cannot open %s", argv[i]+11);
+ exit(EXIT_FAILURE);
+ }
} else
usage();
}
@@ -670,7 +753,11 @@ int main(int argc, char **argv)
read_map(stdin);
sort_symbols();
optimize_token_table();
- write_src();
-
+ write_src(inpadp, opad);
+ if (opadf) {
+ fprintf(opadf, "--pad=%d,%d,%d,%d\n",
+ opad[0], opad[1], opad[2], opad[3]);
+ fclose(opadf);
+ }
return 0;
}
--
1.8.5.2


\
 
 \ /
  Last update: 2014-02-08 09:41    [W:0.078 / U:2.740 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site