This reimplements commit 951bcae6c5a0 ("kallsyms: Avoid weak references
for kallsyms symbols").
I am not a big fan of PROVIDE() because it always satisfies the linker
even in situations that should result in a link error. In other words,
it can potentially shift a compile-time error into a run-time error.
Duplicating kallsyms_* in vmlinux.lds.h also reduces maintainability.
I shuffled scripts/link-vmlinux.sh to prepend one more kallsyms step.
The following logs illustrates how it works.
[Before]
LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.o
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.o
LD vmlinux
[After]
KSYMS .tmp_vmlinux.kallsyms0.S # added
AS .tmp_vmlinux.kallsyms0.o # added
LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.o
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.o
LD vmlinux
Step 0 takes /dev/null as input, and generates .tmp_vmlinux.kallsyms0.o,
which has a valid kallsyms format with zero symbols, and can be linked
to vmlinux. Since it is really small, the added compile-time cost is
negligible.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
include/asm-generic/vmlinux.lds.h | 19 -------------
kernel/kallsyms_internal.h | 5 ----
scripts/kallsyms.c | 6 -----
scripts/link-vmlinux.sh | 45 ++++++++++++++++---------------
4 files changed, 24 insertions(+), 51 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 870753fbb123..9752eb420ffa 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -448,30 +448,11 @@
#endif
#endif
-/*
- * Some symbol definitions will not exist yet during the first pass of the
- * link, but are guaranteed to exist in the final link. Provide preliminary
- * definitions that will be superseded in the final link to avoid having to
- * rely on weak external linkage, which requires a GOT when used in position
- * independent code.
- */
-#define PRELIMINARY_SYMBOL_DEFINITIONS \
- PROVIDE(kallsyms_addresses = .); \
- PROVIDE(kallsyms_offsets = .); \
- PROVIDE(kallsyms_names = .); \
- PROVIDE(kallsyms_num_syms = .); \
- PROVIDE(kallsyms_relative_base = .); \
- PROVIDE(kallsyms_token_table = .); \
- PROVIDE(kallsyms_token_index = .); \
- PROVIDE(kallsyms_markers = .); \
- PROVIDE(kallsyms_seqs_of_names = .);
-
/*
* Read only Data
*/
#define RO_DATA(align) \
. = ALIGN((align)); \
- PRELIMINARY_SYMBOL_DEFINITIONS \
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
__start_rodata = .; \
*(.rodata) *(.rodata.*) \
diff --git a/kernel/kallsyms_internal.h b/kernel/kallsyms_internal.h
index 85480274fc8f..925f2ab22639 100644
--- a/kernel/kallsyms_internal.h
+++ b/kernel/kallsyms_internal.h
@@ -4,11 +4,6 @@
#include <linux/types.h>
-/*
- * These will be re-linked against their real values during the second link
- * stage. Preliminary values must be provided in the linker script using the
- * PROVIDE() directive so that the first link stage can complete successfully.
- */
extern const unsigned long kallsyms_addresses[];
extern const int kallsyms_offsets[];
extern const u8 kallsyms_names[];
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 653b92f6d4c8..6b90f52fd707 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -246,12 +246,6 @@ static void shrink_table(void)
}
}
table_cnt = pos;
-
- /* When valid symbol is not registered, exit to error */
- if (!table_cnt) {
- fprintf(stderr, "No valid symbol.\n");
- exit(1);
- }
}
static void read_map(const char *in)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 7aca51b24e9f..242a92e24f20 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -165,27 +165,25 @@ kallsyms()
kallsymopt="${kallsymopt} --lto-clang"
fi
- info KSYMS ${2}
- scripts/kallsyms ${kallsymopt} ${1} > ${2}
+ info KSYMS "${2}.S"
+ scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S"
+
+ info AS "${2}.o"
+ ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
+ ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
+ -c -o "${2}.o" "${2}.S"
+ kallsymso=${2}.o
}
# Perform one step in kallsyms generation, including temporary linking of
# vmlinux.
kallsyms_step()
{
- kallsymso_prev=${kallsymso}
kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
- kallsymso=${kallsyms_vmlinux}.o
- kallsyms_S=${kallsyms_vmlinux}.S
- vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
- mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms
- kallsyms ${kallsyms_vmlinux}.syms ${kallsyms_S}
-
- info AS ${kallsymso}
- ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
- ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
- -c -o ${kallsymso} ${kallsyms_S}
+ vmlinux_link "${kallsyms_vmlinux}" "${kallsymso}" "${btf_vmlinux_bin_o}"
+ mksysmap "${kallsyms_vmlinux}" "${kallsyms_vmlinux}.syms"
+ kallsyms "${kallsyms_vmlinux}.syms" "${kallsyms_vmlinux}"
}
# Create map file with all symbols from ${1}
@@ -235,15 +233,15 @@ if is_enabled CONFIG_DEBUG_INFO_BTF; then
fi
kallsymso=""
-kallsymso_prev=""
-kallsyms_vmlinux=""
if is_enabled CONFIG_KALLSYMS; then
# kallsyms support
# Generate section listing all symbols and add it into vmlinux
- # It's a three step process:
+ # It's a four step process:
+ # 0) Generate a dummy __kallsyms, which has zero symbols, but a valid
+ # format.
# 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
- # but __kallsyms is empty.
+ # with a dummy __kallsyms.
# Running kallsyms on that gives us .tmp_kallsyms1.o with
# the right size
# 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
@@ -262,13 +260,18 @@ if is_enabled CONFIG_KALLSYMS; then
# a) Verify that the System.map from vmlinux matches the map from
# ${kallsymso}.
- kallsyms_step 1
- kallsyms_step 2
+ # step 0
+ kallsyms /dev/null .tmp_vmlinux.kallsyms0
- # step 3
- size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
+ # step 1
+ kallsyms_step 1
+ size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
+
+ # step 2
+ kallsyms_step 2
size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
+ # step 3
if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
kallsyms_step 3
fi
--
2.40.1Hi Masahiro,
kernel test robot noticed the following build errors:
[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on linus/master masahiroy-kbuild/fixes next-20240521]
[cannot apply to v6.9]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Masahiro-Yamada/kbuild-avoid-unneeded-kallsyms-step-3/20240520-204508
base: https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link: https://lore.kernel.org/r/20240520124212.2351033-5-masahiroy%40kernel.org
patch subject: [PATCH 4/4] kbuild: remove PROVIDE() for kallsyms symbols
config: x86_64-rhel-8.3-bpf (https://download.01.org/0day-ci/archive/20240521/202405211448.fglQOQ9W-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240521/202405211448.fglQOQ9W-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405211448.fglQOQ9W-lkp@intel.com/
All errors (new ones prefixed by >>):
ld: vmlinux.o: in function `get_symbol_offset':
>> kernel/kallsyms.c:125:(.text+0x2111af): undefined reference to `kallsyms_markers'
>> ld: kernel/kallsyms.c:125:(.text+0x2111b5): undefined reference to `kallsyms_names'
ld: kernel/kallsyms.c:146:(.text+0x2111eb): undefined reference to `kallsyms_names'
ld: vmlinux.o: in function `get_symbol_pos':
>> kernel/kallsyms.c:330:(.text+0x211218): undefined reference to `kallsyms_relative_base'
>> ld: kernel/kallsyms.c:330:(.text+0x211226): undefined reference to `kallsyms_num_syms'
ld: vmlinux.o: in function `kallsyms_sym_address':
>> kernel/kallsyms.c:159:(.text+0x211245): undefined reference to `kallsyms_offsets'
>> ld: kernel/kallsyms.c:159:(.text+0x211285): undefined reference to `kallsyms_offsets'
ld: kernel/kallsyms.c:159:(.text+0x211296): undefined reference to `kallsyms_offsets'
ld: kernel/kallsyms.c:159:(.text+0x2112b7): undefined reference to `kallsyms_offsets'
ld: kernel/kallsyms.c:159:(.text+0x2112ec): undefined reference to `kallsyms_offsets'
ld: vmlinux.o: in function `get_ksymbol_mod':
>> kernel/kallsyms.c:623:(.text+0x211434): undefined reference to `kallsyms_num_syms'
ld: vmlinux.o: in function `kallsyms_expand_symbol':
>> kernel/kallsyms.c:50:(.text+0x21167d): undefined reference to `kallsyms_names'
ld: kernel/kallsyms.c:51:(.text+0x211684): undefined reference to `kallsyms_names'
>> ld: kernel/kallsyms.c:73:(.text+0x2116b6): undefined reference to `kallsyms_token_index'
>> ld: kernel/kallsyms.c:73:(.text+0x2116bf): undefined reference to `kallsyms_token_table'
ld: kernel/kallsyms.c:77:(.text+0x2116c6): undefined reference to `kallsyms_token_table'
ld: vmlinux.o: in function `update_iter':
kernel/kallsyms.c:740:(.text+0x211757): undefined reference to `kallsyms_num_syms'
ld: vmlinux.o: in function `kallsyms_sym_address':
kernel/kallsyms.c:159:(.text+0x211782): undefined reference to `kallsyms_offsets'
>> ld: kernel/kallsyms.c:163:(.text+0x211790): undefined reference to `kallsyms_relative_base'
ld: vmlinux.o: in function `kallsyms_get_symbol_type':
kernel/kallsyms.c:108:(.text+0x21179e): undefined reference to `kallsyms_names'
ld: kernel/kallsyms.c:108:(.text+0x2117aa): undefined reference to `kallsyms_token_index'
ld: vmlinux.o: in function `get_ksymbol_core':
>> kernel/kallsyms.c:693:(.text+0x2117b1): undefined reference to `kallsyms_token_table'
ld: vmlinux.o: in function `kallsyms_lookup_names':
kernel/kallsyms.c:218:(.text+0x211a48): undefined reference to `kallsyms_num_syms'
ld: vmlinux.o: in function `get_symbol_seq':
>> kernel/kallsyms.c:203:(.text+0x211a83): undefined reference to `kallsyms_seqs_of_names'
>> ld: kernel/kallsyms.c:203:(.text+0x211a90): undefined reference to `kallsyms_seqs_of_names'
ld: kernel/kallsyms.c:203:(.text+0x211a9c): undefined reference to `kallsyms_seqs_of_names'
ld: kernel/kallsyms.c:203:(.text+0x211af2): undefined reference to `kallsyms_seqs_of_names'
ld: kernel/kallsyms.c:203:(.text+0x211aff): undefined reference to `kallsyms_seqs_of_names'
ld: vmlinux.o:kernel/kallsyms.c:203: more undefined references to `kallsyms_seqs_of_names' follow
ld: vmlinux.o: in function `kallsyms_sym_address':
kernel/kallsyms.c:159:(.text+0x211fb0): undefined reference to `kallsyms_offsets'
ld: kernel/kallsyms.c:163:(.text+0x211fbe): undefined reference to `kallsyms_relative_base'
ld: vmlinux.o: in function `get_symbol_seq':
kernel/kallsyms.c:203:(.text+0x212049): undefined reference to `kallsyms_seqs_of_names'
ld: kernel/kallsyms.c:203:(.text+0x212056): undefined reference to `kallsyms_seqs_of_names'
ld: kernel/kallsyms.c:203:(.text+0x21205d): undefined reference to `kallsyms_seqs_of_names'
ld: vmlinux.o: in function `kallsyms_sym_address':
kernel/kallsyms.c:159:(.text+0x212071): undefined reference to `kallsyms_offsets'
ld: kernel/kallsyms.c:163:(.text+0x21207f): undefined reference to `kallsyms_relative_base'
ld: vmlinux.o: in function `kallsyms_on_each_symbol':
kernel/kallsyms.c:293:(.text+0x2120e5): undefined reference to `kallsyms_num_syms'
ld: vmlinux.o: in function `kallsyms_sym_address':
kernel/kallsyms.c:159:(.text+0x21214b): undefined reference to `kallsyms_offsets'
ld: kernel/kallsyms.c:163:(.text+0x212159): undefined reference to `kallsyms_relative_base'
ld: kernel/kallsyms.c:163:(.text+0x212224): undefined reference to `kallsyms_relative_base'
ld: vmlinux.o: in function `get_symbol_seq':
kernel/kallsyms.c:203:(.text+0x212239): undefined reference to `kallsyms_seqs_of_names'
ld: kernel/kallsyms.c:203:(.text+0x212240): undefined reference to `kallsyms_seqs_of_names'
ld: kernel/kallsyms.c:203:(.text+0x212253): undefined reference to `kallsyms_seqs_of_names'
ld: vmlinux.o: in function `kallsyms_sym_address':
kernel/kallsyms.c:159:(.text+0x21225f): undefined reference to `kallsyms_offsets'
ld: vmlinux.o: in function `crash_save_vmcoreinfo_init':
>> kernel/vmcore_info.c:214:(.init.text+0x429d6): undefined reference to `kallsyms_names'
>> ld: kernel/vmcore_info.c:215:(.init.text+0x429f0): undefined reference to `kallsyms_num_syms'
>> ld: kernel/vmcore_info.c:216:(.init.text+0x42a0a): undefined reference to `kallsyms_token_table'
>> ld: kernel/vmcore_info.c:217:(.init.text+0x42a24): undefined reference to `kallsyms_token_index'
>> ld: kernel/vmcore_info.c:219:(.init.text+0x42a3e): undefined reference to `kallsyms_offsets'
>> ld: kernel/vmcore_info.c:220:(.init.text+0x42a58): undefined reference to `kallsyms_relative_base'
pahole: .tmp_vmlinux.btf: Invalid argument
.btf.vmlinux.bin.o: file not recognized: file format not recognized
vim +125 kernel/kallsyms.c
^1da177e4c3f41 Linus Torvalds 2005-04-16 36
ad6ccfad6f759a Manish Katiyar 2009-05-12 37 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 38 * Expand a compressed symbol data into the resulting uncompressed string,
e3f26752f0f8a6 Chen Gang 2013-04-15 39 * if uncompressed string is too long (>= maxlen), it will be truncated,
ad6ccfad6f759a Manish Katiyar 2009-05-12 40 * given the offset to where the symbol is in the compressed stream.
ad6ccfad6f759a Manish Katiyar 2009-05-12 41 */
e3f26752f0f8a6 Chen Gang 2013-04-15 42 static unsigned int kallsyms_expand_symbol(unsigned int off,
e3f26752f0f8a6 Chen Gang 2013-04-15 43 char *result, size_t maxlen)
^1da177e4c3f41 Linus Torvalds 2005-04-16 44 {
^1da177e4c3f41 Linus Torvalds 2005-04-16 45 int len, skipped_first = 0;
cde26a6e17ec36 Masahiro Yamada 2020-02-02 46 const char *tptr;
cde26a6e17ec36 Masahiro Yamada 2020-02-02 47 const u8 *data;
^1da177e4c3f41 Linus Torvalds 2005-04-16 48
ad6ccfad6f759a Manish Katiyar 2009-05-12 49 /* Get the compressed symbol length from the first symbol byte. */
^1da177e4c3f41 Linus Torvalds 2005-04-16 @50 data = &kallsyms_names[off];
^1da177e4c3f41 Linus Torvalds 2005-04-16 51 len = *data;
^1da177e4c3f41 Linus Torvalds 2005-04-16 52 data++;
73bbb94466fd3f Miguel Ojeda 2021-04-05 53 off++;
73bbb94466fd3f Miguel Ojeda 2021-04-05 54
73bbb94466fd3f Miguel Ojeda 2021-04-05 55 /* If MSB is 1, it is a "big" symbol, so needs an additional byte. */
73bbb94466fd3f Miguel Ojeda 2021-04-05 56 if ((len & 0x80) != 0) {
73bbb94466fd3f Miguel Ojeda 2021-04-05 57 len = (len & 0x7F) | (*data << 7);
73bbb94466fd3f Miguel Ojeda 2021-04-05 58 data++;
73bbb94466fd3f Miguel Ojeda 2021-04-05 59 off++;
73bbb94466fd3f Miguel Ojeda 2021-04-05 60 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 61
ad6ccfad6f759a Manish Katiyar 2009-05-12 62 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 63 * Update the offset to return the offset for the next symbol on
ad6ccfad6f759a Manish Katiyar 2009-05-12 64 * the compressed stream.
ad6ccfad6f759a Manish Katiyar 2009-05-12 65 */
73bbb94466fd3f Miguel Ojeda 2021-04-05 66 off += len;
^1da177e4c3f41 Linus Torvalds 2005-04-16 67
ad6ccfad6f759a Manish Katiyar 2009-05-12 68 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 69 * For every byte on the compressed symbol data, copy the table
ad6ccfad6f759a Manish Katiyar 2009-05-12 70 * entry for that byte.
ad6ccfad6f759a Manish Katiyar 2009-05-12 71 */
^1da177e4c3f41 Linus Torvalds 2005-04-16 72 while (len) {
^1da177e4c3f41 Linus Torvalds 2005-04-16 @73 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
^1da177e4c3f41 Linus Torvalds 2005-04-16 74 data++;
^1da177e4c3f41 Linus Torvalds 2005-04-16 75 len--;
^1da177e4c3f41 Linus Torvalds 2005-04-16 76
^1da177e4c3f41 Linus Torvalds 2005-04-16 77 while (*tptr) {
^1da177e4c3f41 Linus Torvalds 2005-04-16 78 if (skipped_first) {
e3f26752f0f8a6 Chen Gang 2013-04-15 79 if (maxlen <= 1)
e3f26752f0f8a6 Chen Gang 2013-04-15 80 goto tail;
^1da177e4c3f41 Linus Torvalds 2005-04-16 81 *result = *tptr;
^1da177e4c3f41 Linus Torvalds 2005-04-16 82 result++;
e3f26752f0f8a6 Chen Gang 2013-04-15 83 maxlen--;
^1da177e4c3f41 Linus Torvalds 2005-04-16 84 } else
^1da177e4c3f41 Linus Torvalds 2005-04-16 85 skipped_first = 1;
^1da177e4c3f41 Linus Torvalds 2005-04-16 86 tptr++;
^1da177e4c3f41 Linus Torvalds 2005-04-16 87 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 88 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 89
e3f26752f0f8a6 Chen Gang 2013-04-15 90 tail:
e3f26752f0f8a6 Chen Gang 2013-04-15 91 if (maxlen)
^1da177e4c3f41 Linus Torvalds 2005-04-16 92 *result = '\0';
^1da177e4c3f41 Linus Torvalds 2005-04-16 93
ad6ccfad6f759a Manish Katiyar 2009-05-12 94 /* Return to offset to the next symbol. */
^1da177e4c3f41 Linus Torvalds 2005-04-16 95 return off;
^1da177e4c3f41 Linus Torvalds 2005-04-16 96 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 97
ad6ccfad6f759a Manish Katiyar 2009-05-12 98 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 99 * Get symbol type information. This is encoded as a single char at the
ad6ccfad6f759a Manish Katiyar 2009-05-12 100 * beginning of the symbol name.
ad6ccfad6f759a Manish Katiyar 2009-05-12 101 */
^1da177e4c3f41 Linus Torvalds 2005-04-16 102 static char kallsyms_get_symbol_type(unsigned int off)
^1da177e4c3f41 Linus Torvalds 2005-04-16 103 {
ad6ccfad6f759a Manish Katiyar 2009-05-12 104 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 105 * Get just the first code, look it up in the token table,
ad6ccfad6f759a Manish Katiyar 2009-05-12 106 * and return the first char from this token.
ad6ccfad6f759a Manish Katiyar 2009-05-12 107 */
^1da177e4c3f41 Linus Torvalds 2005-04-16 108 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
^1da177e4c3f41 Linus Torvalds 2005-04-16 109 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 110
^1da177e4c3f41 Linus Torvalds 2005-04-16 111
ad6ccfad6f759a Manish Katiyar 2009-05-12 112 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 113 * Find the offset on the compressed stream given and index in the
ad6ccfad6f759a Manish Katiyar 2009-05-12 114 * kallsyms array.
ad6ccfad6f759a Manish Katiyar 2009-05-12 115 */
^1da177e4c3f41 Linus Torvalds 2005-04-16 116 static unsigned int get_symbol_offset(unsigned long pos)
^1da177e4c3f41 Linus Torvalds 2005-04-16 117 {
aad094701c6355 Jan Beulich 2006-12-08 118 const u8 *name;
73bbb94466fd3f Miguel Ojeda 2021-04-05 119 int i, len;
^1da177e4c3f41 Linus Torvalds 2005-04-16 120
ad6ccfad6f759a Manish Katiyar 2009-05-12 121 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 122 * Use the closest marker we have. We have markers every 256 positions,
ad6ccfad6f759a Manish Katiyar 2009-05-12 123 * so that should be close enough.
ad6ccfad6f759a Manish Katiyar 2009-05-12 124 */
^1da177e4c3f41 Linus Torvalds 2005-04-16 @125 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
^1da177e4c3f41 Linus Torvalds 2005-04-16 126
ad6ccfad6f759a Manish Katiyar 2009-05-12 127 /*
ad6ccfad6f759a Manish Katiyar 2009-05-12 128 * Sequentially scan all the symbols up to the point we're searching
ad6ccfad6f759a Manish Katiyar 2009-05-12 129 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
ad6ccfad6f759a Manish Katiyar 2009-05-12 130 * so we just need to add the len to the current pointer for every
ad6ccfad6f759a Manish Katiyar 2009-05-12 131 * symbol we wish to skip.
ad6ccfad6f759a Manish Katiyar 2009-05-12 132 */
73bbb94466fd3f Miguel Ojeda 2021-04-05 133 for (i = 0; i < (pos & 0xFF); i++) {
73bbb94466fd3f Miguel Ojeda 2021-04-05 134 len = *name;
73bbb94466fd3f Miguel Ojeda 2021-04-05 135
73bbb94466fd3f Miguel Ojeda 2021-04-05 136 /*
73bbb94466fd3f Miguel Ojeda 2021-04-05 137 * If MSB is 1, it is a "big" symbol, so we need to look into
73bbb94466fd3f Miguel Ojeda 2021-04-05 138 * the next byte (and skip it, too).
73bbb94466fd3f Miguel Ojeda 2021-04-05 139 */
73bbb94466fd3f Miguel Ojeda 2021-04-05 140 if ((len & 0x80) != 0)
73bbb94466fd3f Miguel Ojeda 2021-04-05 141 len = ((len & 0x7F) | (name[1] << 7)) + 1;
73bbb94466fd3f Miguel Ojeda 2021-04-05 142
73bbb94466fd3f Miguel Ojeda 2021-04-05 143 name = name + len + 1;
73bbb94466fd3f Miguel Ojeda 2021-04-05 144 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 145
^1da177e4c3f41 Linus Torvalds 2005-04-16 146 return name - kallsyms_names;
^1da177e4c3f41 Linus Torvalds 2005-04-16 147 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 148
30f3bb09778de6 Zhen Lei 2022-11-15 149 unsigned long kallsyms_sym_address(int idx)
2213e9a66bb87d Ard Biesheuvel 2016-03-15 150 {
2213e9a66bb87d Ard Biesheuvel 2016-03-15 151 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
2213e9a66bb87d Ard Biesheuvel 2016-03-15 152 return kallsyms_addresses[idx];
2213e9a66bb87d Ard Biesheuvel 2016-03-15 153
2213e9a66bb87d Ard Biesheuvel 2016-03-15 154 /* values are unsigned offsets if --absolute-percpu is not in effect */
2213e9a66bb87d Ard Biesheuvel 2016-03-15 155 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
2213e9a66bb87d Ard Biesheuvel 2016-03-15 156 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
2213e9a66bb87d Ard Biesheuvel 2016-03-15 157
2213e9a66bb87d Ard Biesheuvel 2016-03-15 158 /* ...otherwise, positive offsets are absolute values */
2213e9a66bb87d Ard Biesheuvel 2016-03-15 @159 if (kallsyms_offsets[idx] >= 0)
2213e9a66bb87d Ard Biesheuvel 2016-03-15 160 return kallsyms_offsets[idx];
2213e9a66bb87d Ard Biesheuvel 2016-03-15 161
2213e9a66bb87d Ard Biesheuvel 2016-03-15 162 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
2213e9a66bb87d Ard Biesheuvel 2016-03-15 @163 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
2213e9a66bb87d Ard Biesheuvel 2016-03-15 164 }
2213e9a66bb87d Ard Biesheuvel 2016-03-15 165
76903a9648744c Yonghong Song 2023-08-25 166 static void cleanup_symbol_name(char *s)
8b8e6b5d3b013b Sami Tolvanen 2021-04-08 167 {
8b8e6b5d3b013b Sami Tolvanen 2021-04-08 168 char *res;
8b8e6b5d3b013b Sami Tolvanen 2021-04-08 169
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 170 if (!IS_ENABLED(CONFIG_LTO_CLANG))
76903a9648744c Yonghong Song 2023-08-25 171 return;
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 172
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 173 /*
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 174 * LLVM appends various suffixes for local functions and variables that
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 175 * must be promoted to global scope as part of LTO. This can break
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 176 * hooking of static functions with kprobes. '.' is not a valid
8cc32a9bbf2934 Yonghong Song 2023-06-28 177 * character in an identifier in C. Suffixes only in LLVM LTO observed:
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 178 * - foo.llvm.[0-9a-f]+
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 179 */
8cc32a9bbf2934 Yonghong Song 2023-06-28 180 res = strstr(s, ".llvm.");
76903a9648744c Yonghong Song 2023-08-25 181 if (res)
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 182 *res = '\0';
6eb4bd92c1cedc Nick Desaulniers 2021-10-04 183
76903a9648744c Yonghong Song 2023-08-25 184 return;
8b8e6b5d3b013b Sami Tolvanen 2021-04-08 185 }
8b8e6b5d3b013b Sami Tolvanen 2021-04-08 186
60443c88f3a89f Zhen Lei 2022-11-02 187 static int compare_symbol_name(const char *name, char *namebuf)
60443c88f3a89f Zhen Lei 2022-11-02 188 {
33f0467fe06934 Yonghong Song 2023-08-24 189 /* The kallsyms_seqs_of_names is sorted based on names after
33f0467fe06934 Yonghong Song 2023-08-24 190 * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled.
33f0467fe06934 Yonghong Song 2023-08-24 191 * To ensure correct bisection in kallsyms_lookup_names(), do
33f0467fe06934 Yonghong Song 2023-08-24 192 * cleanup_symbol_name(namebuf) before comparing name and namebuf.
33f0467fe06934 Yonghong Song 2023-08-24 193 */
33f0467fe06934 Yonghong Song 2023-08-24 194 cleanup_symbol_name(namebuf);
33f0467fe06934 Yonghong Song 2023-08-24 195 return strcmp(name, namebuf);
60443c88f3a89f Zhen Lei 2022-11-02 196 }
60443c88f3a89f Zhen Lei 2022-11-02 197
19bd8981dc2ee3 Zhen Lei 2022-11-02 198 static unsigned int get_symbol_seq(int index)
19bd8981dc2ee3 Zhen Lei 2022-11-02 199 {
19bd8981dc2ee3 Zhen Lei 2022-11-02 200 unsigned int i, seq = 0;
19bd8981dc2ee3 Zhen Lei 2022-11-02 201
19bd8981dc2ee3 Zhen Lei 2022-11-02 202 for (i = 0; i < 3; i++)
19bd8981dc2ee3 Zhen Lei 2022-11-02 @203 seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i];
19bd8981dc2ee3 Zhen Lei 2022-11-02 204
19bd8981dc2ee3 Zhen Lei 2022-11-02 205 return seq;
19bd8981dc2ee3 Zhen Lei 2022-11-02 206 }
19bd8981dc2ee3 Zhen Lei 2022-11-02 207
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Tue, May 21, 2024 at 4:13 PM kernel test robot <lkp@intel.com> wrote: > > Hi Masahiro, > > kernel test robot noticed the following build errors: > > [auto build test ERROR on masahiroy-kbuild/for-next] > [also build test ERROR on linus/master masahiroy-kbuild/fixes next-20240521] > [cannot apply to v6.9] > [If your patch is applied to the wrong git tree, kindly drop us a note. > And when submitting patch, we suggest to use '--base' as documented in > https://git-scm.com/docs/git-format-patch#_base_tree_information] > > url: https://github.com/intel-lab-lkp/linux/commits/Masahiro-Yamada/kbuild-avoid-unneeded-kallsyms-step-3/20240520-204508 > base: https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next > patch link: https://lore.kernel.org/r/20240520124212.2351033-5-masahiroy%40kernel.org > patch subject: [PATCH 4/4] kbuild: remove PROVIDE() for kallsyms symbols > config: x86_64-rhel-8.3-bpf (https://download.01.org/0day-ci/archive/20240521/202405211448.fglQOQ9W-lkp@intel.com/config) > compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0 > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240521/202405211448.fglQOQ9W-lkp@intel.com/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot <lkp@intel.com> > | Closes: https://lore.kernel.org/oe-kbuild-all/202405211448.fglQOQ9W-lkp@intel.com/ > > All errors (new ones prefixed by >>): Thanks, I will move kallsyms step 0 before btf creation. -- Best Regards Masahiro Yamada
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