On 2022/12/15 21:58, Leizhen (ThunderTown) wrote:
On 2022/12/15 21:24, Geert Uytterhoeven wrote:
Hi Zhen,
CC Jason
On Thu, Dec 15, 2022 at 1:34 PM Leizhen (ThunderTown)
<thunder.leizhen@xxxxxxxxxx> wrote:
On 2022/12/15 17:39, Geert Uytterhoeven wrote:
On Thu, Dec 15, 2022 at 10:16 AM Leizhen (ThunderTown)
<thunder.leizhen@xxxxxxxxxx> wrote:
On 2022/12/15 16:50, Geert Uytterhoeven wrote:
On Tue, Nov 15, 2022 at 9:41 AM Zhen Lei <thunder.leizhen@xxxxxxxxxx> wrote:
Added test cases for basic functions and performance of functions
kallsyms_lookup_name(), kallsyms_on_each_symbol() and
kallsyms_on_each_match_symbol(). It also calculates the compression rate
of the kallsyms compression algorithm for the current symbol set.
The basic functions test begins by testing a set of symbols whose address
values are known. Then, traverse all symbol addresses and find the
corresponding symbol name based on the address. It's impossible to
determine whether these addresses are correct, but we can use the above
three functions along with the addresses to test each other. Due to the
traversal operation of kallsyms_on_each_symbol() is too slow, only 60
symbols can be tested in one second, so let it test on average once
every 128 symbols. The other two functions validate all symbols.
If the basic functions test is passed, print only performance test
results. If the test fails, print error information, but do not perform
subsequent performance tests.
Start self-test automatically after system startup if
CONFIG_KALLSYMS_SELFTEST=y.
Example of output content: (prefix 'kallsyms_selftest:' is omitted
start
---------------------------------------------------------
| nr_symbols | compressed size | original size | ratio(%) |
|---------------------------------------------------------|
| 107543 | 1357912 | 2407433 | 56.40 |
---------------------------------------------------------
kallsyms_lookup_name() looked up 107543 symbols
The time spent on each symbol is (ns): min=630, max=35295, avg=7353
kallsyms_on_each_symbol() traverse all: 11782628 ns
kallsyms_on_each_match_symbol() traverse all: 9261 ns
finish
Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Thanks for your patch, which is now commit 30f3bb09778de64e ("kallsyms:
Add self-test facility") in linus/master.
I gave this a try on m68k (atari_defconfig + CONFIG_KALLSYMS_SELFTEST=y),
but it failed:
start
kallsyms_lookup_name() for kallsyms_test_func_static failed:
addr=0, expect 60ab0
kallsyms_lookup_name() for kallsyms_test_func failed: addr=0, expect 60ac0
kallsyms_lookup_name() for kallsyms_test_func_weak failed: addr=0,
expect 60ac2
kallsyms_lookup_name() for vmalloc failed: addr=0, expect c272a
kallsyms_lookup_name() for vfree failed: addr=0, expect c2142
kallsyms_on_each_match_symbol() for kallsyms_test_func_static
failed: count=0, addr=0, expect 60ab0
kallsyms_on_each_match_symbol() for kallsyms_test_func failed:
count=0, addr=0, expect 60ac0
kallsyms_on_each_match_symbol() for kallsyms_test_func_weak
failed: count=0, addr=0, expect 60ac2
kallsyms_on_each_match_symbol() for vmalloc failed: count=0,
addr=0, expect c272a
kallsyms_on_each_match_symbol() for vfree failed: count=0, addr=0,
expect c2142
abort
Given all addresses are zero, it looks like some required functionality
or config option is missing.
$ grep SYM .config
CONFIG_KALLSYMS=y
CONFIG_KALLSYMS_SELFTEST=y
CONFIG_KALLSYMS_BASE_RELATIVE=y
# CONFIG_ASYMMETRIC_KEY_TYPE is not set
CONFIG_SYMBOLIC_ERRNAME=y
# CONFIG_STRIP_ASM_SYMS is not set
CONFIG_KALLSYMS_SELFTEST
Do you have a clue?
cat /proc/kallsyms | grep kallsyms_test_func
Let's see if the compiler-generated symbols have some special suffixes.
Thanks, looks normal to me:
atari:~# cat /proc/kallsyms | grep kallsyms_test_func
00060ab0 t kallsyms_test_func_static
00060ac0 T kallsyms_test_func
00060ac2 W kallsyms_test_func_weak
atari:~#
It's incredible. I don't have a m68k environment and I'm trying to build a qemu
environment. If you're in a hurry and willing, you can apply the debugging patch
in the attachment. I'd like to see what's wrong. Use "dmesg | grep tst" to collect
the output information.
Still fails:
tst: found kallsyms_test_func at index=12845
tst: [12533] = kallsyms_test_func, seq=17370, offset=191223
tst: [18800] = kallsyms_test_func, seq=23193, offset=259263
tst: [21934] = kallsyms_test_func, seq=2527, offset=22331
tst: [23501] = kallsyms_test_func, seq=11792, offset=126366
tst: [24284] = kallsyms_test_func, seq=8427, offset=87395
tst: [24676] = kallsyms_test_func, seq=21896, offset=243536
tst: [24872] = kallsyms_test_func, seq=22571, offset=251856
tst: [24970] = kallsyms_test_func, seq=23264, offset=260074
tst: [25019] = kallsyms_test_func, seq=9003, offset=93752
tst: [25043] = kallsyms_test_func, seq=14324, offset=155117
tst: [25055] = kallsyms_test_func, seq=5942, offset=62266
tst: [25061] = kallsyms_test_func, seq=14347, offset=155467
tst: [25064] = kallsyms_test_func, seq=14350, offset=155512
tst: [25066] = kallsyms_test_func, seq=14346, offset=155457
tst: [25067] = kallsyms_test_func, seq=14354, offset=155565
- pr_warn("tst: [%d] = %s, seq=%d, offset=%d\n", mid, name, seq, off);
+ pr_warn("tst: [%d] = %s, seq=%d, offset=%d\n", mid, namebuf, seq, off);
Sorry, a variable in the debugging code is incorrectly written. 'name' should
be replaced with 'namebuf', then we can see which function the comparison is wrong.
I attached debug patch v2.
However, the binary search sequence looks very suspicious.
After investigation, it turns out compare_symbol_name() and strcmp()
always return positive numbers.
Looks like commit 3bc753c06dd02a35 ("kbuild: treat char as always
unsigned") is to blame.
Oh, maybe you can "git reset --hard 30f3bb09778de64" and try again.
30f3bb09778de64 kallsyms: Add self-test facility
But the latest kernel is OK on x86. So other patches are unlikely to
affect this function.
Is m68k big-endian?
Changing:
--- a/arch/m68k/include/asm/string.h
+++ b/arch/m68k/include/asm/string.h
@@ -42,7 +42,7 @@ static inline char *strncpy(char *dest, const
char *src, size_t n)
#define __HAVE_ARCH_STRCMP
static inline int strcmp(const char *cs, const char *ct)
{
- char res;
+ signed char res;
asm ("\n"
"1: move.b (%0)+,%2\n" /* get *cs */
fixes strcmp, but the test still fails:
tst: kallsyms_lookup_names() is OK, name=kallsyms_test_func, i=0
i=0, i is impossible zero. Maybe kallsyms_lookup_names() always return success now.
kallsyms_selftest: kallsyms_lookup_name() for
kallsyms_test_func_static failed: addr=8e1c, expect 60cd4
kallsyms_selftest: kallsyms_lookup_name() for kallsyms_test_func
failed: addr=8e1c, expect 60ce4
kallsyms_selftest: kallsyms_lookup_name() for
kallsyms_test_func_weak failed: addr=8e1c, expect 60ce6
kallsyms_selftest: kallsyms_lookup_name() for vmalloc failed:
addr=8e1c, expect c2946
kallsyms_selftest: kallsyms_lookup_name() for vfree failed:
addr=8e1c, expect c235e
kallsyms_selftest: kallsyms_on_each_match_symbol() for
kallsyms_test_func_static failed: count=25068, addr=1f3d3c, expect
60cd4
kallsyms_selftest: kallsyms_on_each_match_symbol() for
kallsyms_test_func failed: count=25068, addr=1f3d3c, expect 60ce4
kallsyms_selftest: kallsyms_on_each_match_symbol() for
kallsyms_test_func_weak failed: count=25068, addr=1f3d3c, expect 60ce6
kallsyms_selftest: kallsyms_on_each_match_symbol() for vmalloc
failed: count=25068, addr=1f3d3c, expect c2946
kallsyms_selftest: kallsyms_on_each_match_symbol() for vfree
failed: count=25068, addr=1f3d3c, expect c235e
kallsyms_selftest: abort
Dropping -funsigned-char doesn't improve upon that...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
.
--
Regards,
Zhen Lei
From c065ac86cfd9153e4fb71bbc06d440a41834b878 Mon Sep 17 00:00:00 2001
From: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Date: Thu, 15 Dec 2022 20:12:38 +0800
Subject: [PATCH v2] kallsyms: debug m68k
Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
---
kernel/kallsyms.c | 57 ++++++++++++++++++++++++++++++++++++++
kernel/kallsyms_selftest.c | 3 ++
2 files changed, 60 insertions(+)
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 83f499182c9aa31..80251da9952b957 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -267,6 +267,63 @@ static int kallsyms_lookup_names(const char *name,
return 0;
}
+void tst_kallsyms_lookup_name(const char *name, void *addr)
+{
+ int i;
+ int ret;
+ int low, mid, high;
+ unsigned int seq, off;
+ char namebuf[KSYM_NAME_LEN];
+
+ ret = kallsyms_lookup_names(name, &i, NULL);
+ if (!ret) {
+ pr_warn("tst: kallsyms_lookup_names() is OK, name=%s, i=%d\n", name, i);
+ if (addr == (void *)kallsyms_sym_address(get_symbol_seq(i)))
+ pr_warn("tst: lookup address is OK\n");
+ return;
+ }
+
+
+ for (i = 0; i < kallsyms_num_syms; i++) {
+ seq = get_symbol_seq(i);
+ off = get_symbol_offset(seq);
+ kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
+ ret = compare_symbol_name(name, namebuf);
+ if (!ret) {
+ pr_warn("tst: found %s at index=%d\n", name, i);
+ if (addr == (void *)kallsyms_sym_address(get_symbol_seq(i)))
+ pr_warn("tst: lookup address is OK\n");
+ break;
+ }
+ }
+
+ if (i == kallsyms_num_syms) {
+ pr_warn("tst: found %s failed\n", name);
+ return;
+ }
+
+ low = 0;
+ high = kallsyms_num_syms - 1;
+
+ while (low <= high) {
+ mid = low + (high - low) / 2;
+ seq = get_symbol_seq(mid);
+ off = get_symbol_offset(seq);
+ kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
+ pr_warn("tst: [%d] = %s, seq=%d, offset=%d\n", mid, namebuf, seq, off);
+ ret = compare_symbol_name(name, namebuf);
+ if (ret > 0)
+ low = mid + 1;
+ else if (ret < 0)
+ high = mid - 1;
+ else
+ break;
+ }
+
+ if (mid == i)
+ pr_warn("tst: binary search is OK\n");
+}
+
/* Lookup the address for this symbol. Returns 0 if not found. */
unsigned long kallsyms_lookup_name(const char *name)
{
diff --git a/kernel/kallsyms_selftest.c b/kernel/kallsyms_selftest.c
index f35d9cc1aab1544..f0f7c9fc72c5d53 100644
--- a/kernel/kallsyms_selftest.c
+++ b/kernel/kallsyms_selftest.c
@@ -293,6 +293,9 @@ static int test_kallsyms_basic_function(void)
unsigned long addr, lookup_addr;
char namebuf[KSYM_NAME_LEN];
struct test_stat *stat, *stat2;
+ extern void tst_kallsyms_lookup_name(const char *name, void *addr);
+
+ tst_kallsyms_lookup_name("kallsyms_test_func", kallsyms_test_func);
stat = kmalloc(sizeof(*stat) * 2, GFP_KERNEL);
if (!stat)
--
2.25.1
