@@ -451,30 +451,11 @@
#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- * definitions that will be superseded in the final link to avoid having to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.*) \
@@ -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[];
@@ -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)
@@ -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
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> --- (no changes since v1) include/asm-generic/vmlinux.lds.h | 19 ------------------- kernel/kallsyms_internal.h | 5 ----- scripts/kallsyms.c | 6 ------ scripts/link-vmlinux.sh | 9 +++++++-- 4 files changed, 7 insertions(+), 32 deletions(-)