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author | Masahiro Yamada <masahiroy@kernel.org> | 2024-06-10 14:25:17 +0300 |
---|---|---|
committer | Masahiro Yamada <masahiroy@kernel.org> | 2024-07-15 19:08:36 +0300 |
commit | c442db3f49f27e5a60a641b2ac9a3c6320796ed6 (patch) | |
tree | 665aa0090b4e1c77ce6e2c2d1b89111c8a5a333e | |
parent | ddf41329839f49dadf26973cd845ea160ac1784d (diff) | |
download | linux-c442db3f49f27e5a60a641b2ac9a3c6320796ed6.tar.xz |
kbuild: remove PROVIDE() for kallsyms symbols
This reimplements commit 951bcae6c5a0 ("kallsyms: Avoid weak references
for kallsyms symbols") because I am not a big fan of PROVIDE().
As an alternative solution, this commit prepends one more kallsyms step.
KSYMS .tmp_vmlinux.kallsyms0.S # added
AS .tmp_vmlinux.kallsyms0.o # added
LD .tmp_vmlinux.btf
BTF .btf.vmlinux.bin.o
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 the empty symbol list, 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>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
-rw-r--r-- | include/asm-generic/vmlinux.lds.h | 19 | ||||
-rw-r--r-- | kernel/kallsyms_internal.h | 5 | ||||
-rw-r--r-- | scripts/kallsyms.c | 6 | ||||
-rwxr-xr-x | scripts/link-vmlinux.sh | 9 |
4 files changed, 7 insertions, 32 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 5703526d6ebf..62b4cb0462e6 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -452,29 +452,10 @@ #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 Provide preliminary - * definitions that will be superseded in the final link to avoid having to - * rely on weak external linkage, which requires a GOT when used in position - * independent code.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 47978efe4797..fa53b5eef553 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -259,12 +259,6 @@ 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 3d9d7257143a..83d605ba7241 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -227,6 +227,10 @@ btf_vmlinux_bin_o= kallsymso= strip_debug= +if is_enabled CONFIG_KALLSYMS; then + kallsyms /dev/null .tmp_vmlinux.kallsyms0 +fi + if is_enabled CONFIG_DEBUG_INFO_BTF; then if ! gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then echo >&2 "Failed to generate BTF for vmlinux" @@ -239,9 +243,10 @@ 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 with empty symbol list. # 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 |