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kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU

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x86-64 was the only user.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250123190747.745588-16-brgerst@gmail.com
This commit is contained in:
Brian Gerst
2025-01-23 14:07:47 -05:00
committed by Ingo Molnar
parent 4b00c1160a
commit 01157ddc58
4 changed files with 13 additions and 78 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
init/Kconfig
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@@ -1869,11 +1869,6 @@ config KALLSYMS_ALL
Say N unless you really need all symbols, or kernel live patching.
config KALLSYMS_ABSOLUTE_PERCPU
bool
depends on KALLSYMS
default n
# end of the "standard kernel features (expert users)" menu
config ARCH_HAS_MEMBARRIER_CALLBACKS

12
kernel/kallsyms.c
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@@ -148,16 +148,8 @@ static unsigned int get_symbol_offset(unsigned long pos)
unsigned long kallsyms_sym_address(int idx)
{
/* values are unsigned offsets if --absolute-percpu is not in effect */
if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
/* ...otherwise, positive offsets are absolute values */
if (kallsyms_offsets[idx] >= 0)
return kallsyms_offsets[idx];
/* ...and negative offsets are relative to kallsyms_relative_base - 1 */
return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
/* values are unsigned offsets */
return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
}
static unsigned int get_symbol_seq(int index)

70
scripts/kallsyms.c
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@@ -5,7 +5,7 @@
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*
* Usage: kallsyms [--all-symbols] [--absolute-percpu] in.map > out.S
* Usage: kallsyms [--all-symbols] in.map > out.S
*
* Table compression uses all the unused char codes on the symbols and
* maps these to the most used substrings (tokens). For instance, it might
@@ -37,7 +37,6 @@ struct sym_entry {
unsigned long long addr;
unsigned int len;
unsigned int seq;
bool percpu_absolute;
unsigned char sym[];
};
@@ -55,14 +54,9 @@ static struct addr_range text_ranges[] = {
#define text_range_text (&text_ranges[0])
#define text_range_inittext (&text_ranges[1])
static struct addr_range percpu_range = {
"__per_cpu_start", "__per_cpu_end", -1ULL, 0
};
static struct sym_entry **table;
static unsigned int table_size, table_cnt;
static int all_symbols;
static int absolute_percpu;
static int token_profit[0x10000];
@@ -73,7 +67,7 @@ static unsigned char best_table_len[256];
static void usage(void)
{
fprintf(stderr, "Usage: kallsyms [--all-symbols] [--absolute-percpu] in.map > out.S\n");
fprintf(stderr, "Usage: kallsyms [--all-symbols] in.map > out.S\n");
exit(1);
}
@@ -164,7 +158,6 @@ static struct sym_entry *read_symbol(FILE *in, char **buf, size_t *buf_len)
return NULL;
check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges));
check_symbol_range(name, addr, &percpu_range, 1);
/* include the type field in the symbol name, so that it gets
* compressed together */
@@ -175,7 +168,6 @@ static struct sym_entry *read_symbol(FILE *in, char **buf, size_t *buf_len)
sym->len = len;
sym->sym[0] = type;
strcpy(sym_name(sym), name);
sym->percpu_absolute = false;
return sym;
}
@@ -319,11 +311,6 @@ static int expand_symbol(const unsigned char *data, int len, char *result)
return total;
}
static bool symbol_absolute(const struct sym_entry *s)
{
return s->percpu_absolute;
}
static int compare_names(const void *a, const void *b)
{
int ret;
@@ -455,22 +442,11 @@ static void write_src(void)
*/
long long offset;
bool overflow;
if (!absolute_percpu) {
offset = table[i]->addr - relative_base;
overflow = offset < 0 || offset > UINT_MAX;
} else if (symbol_absolute(table[i])) {
offset = table[i]->addr;
overflow = offset < 0 || offset > INT_MAX;
} else {
offset = relative_base - table[i]->addr - 1;
overflow = offset < INT_MIN || offset >= 0;
}
if (overflow) {
offset = table[i]->addr - relative_base;
if (offset < 0 || offset > UINT_MAX) {
fprintf(stderr, "kallsyms failure: "
"%s symbol value %#llx out of range in relative mode\n",
symbol_absolute(table[i]) ? "absolute" : "relative",
"relative symbol value %#llx out of range\n",
table[i]->addr);
exit(EXIT_FAILURE);
}
@@ -725,36 +701,15 @@ static void sort_symbols(void)
qsort(table, table_cnt, sizeof(table[0]), compare_symbols);
}
static void make_percpus_absolute(void)
{
unsigned int i;
for (i = 0; i < table_cnt; i++)
if (symbol_in_range(table[i], &percpu_range, 1)) {
/*
* Keep the 'A' override for percpu symbols to
* ensure consistent behavior compared to older
* versions of this tool.
*/
table[i]->sym[0] = 'A';
table[i]->percpu_absolute = true;
}
}
/* find the minimum non-absolute symbol address */
static void record_relative_base(void)
{
unsigned int i;
for (i = 0; i < table_cnt; i++)
if (!symbol_absolute(table[i])) {
/*
* The table is sorted by address.
* Take the first non-absolute symbol value.
*/
relative_base = table[i]->addr;
return;
}
/*
* The table is sorted by address.
* Take the first symbol value.
*/
if (table_cnt)
relative_base = table[0]->addr;
}
int main(int argc, char **argv)
@@ -762,7 +717,6 @@ int main(int argc, char **argv)
while (1) {
static const struct option long_options[] = {
{"all-symbols", no_argument, &all_symbols, 1},
{"absolute-percpu", no_argument, &absolute_percpu, 1},
{},
};
@@ -779,8 +733,6 @@ int main(int argc, char **argv)
read_map(argv[optind]);
shrink_table();
if (absolute_percpu)
make_percpus_absolute();
sort_symbols();
record_relative_base();
optimize_token_table();

4
scripts/link-vmlinux.sh
View File

@@ -144,10 +144,6 @@ kallsyms()
kallsymopt="${kallsymopt} --all-symbols"
fi
if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
kallsymopt="${kallsymopt} --absolute-percpu"
fi
info KSYMS "${2}.S"
scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S"