@@ -79,6 +79,7 @@ SCCS
System.map*
TAGS
aconf
+addaddrs
af_names.h
aic7*reg.h*
aic7*reg_print.c*
@@ -1570,6 +1570,16 @@ config POSIX_TIMERS
If unsure say y.
+config KALLMODSYMS
+ default y
+ bool "Enable support for /proc/kallmodsyms" if EXPERT
+ depends on KALLSYMS
+ select VMLINUX_MAP
+ help
+ This option enables the /proc/kallmodsyms file, which unambiguously
+ maps built-in kernel symbols and their associated object files and
+ modules to addresses.
+
config PRINTK
default y
bool "Enable support for printk" if EXPERT
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
+/addaddrs
/asn1_compiler
/bin2c
/generate_rust_target
@@ -5,6 +5,7 @@
hostprogs-always-$(CONFIG_BUILD_BIN2C) += bin2c
hostprogs-always-$(CONFIG_KALLSYMS) += kallsyms
+hostprogs-always-$(CONFIG_KALLMODSYMS) += addaddrs
hostprogs-always-$(BUILD_C_RECORDMCOUNT) += recordmcount
hostprogs-always-$(CONFIG_BUILDTIME_TABLE_SORT) += sorttable
hostprogs-always-$(CONFIG_ASN1) += asn1_compiler
@@ -27,6 +27,10 @@ ifdef CONFIG_LTO_CLANG
initcalls-lds := .tmp_initcalls.lds
endif
+ifneq ($(CONFIG_VMLINUX_MAP)$(CONFIG_KALLMODSYMS),)
+KBUILD_MAPFLAGS = -Map=$@.map
+endif
+
# objtool for vmlinux.o
# ---------------------------------------------------------------------------
#
@@ -47,7 +51,7 @@ objtool-args = $(vmlinux-objtool-args-y) --link
quiet_cmd_ld_vmlinux.o = LD $@
cmd_ld_vmlinux.o = \
$(LD) ${KBUILD_LDFLAGS} -r -o $@ \
- $(addprefix -T , $(initcalls-lds)) \
+ $(KBUILD_MAPFLAGS) $(addprefix -T , $(initcalls-lds)) \
--whole-archive vmlinux.a --no-whole-archive \
--start-group $(KBUILD_VMLINUX_LIBS) --end-group \
$(cmd_objtool)
new file mode 100644
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Used only by link-vmlinux.sh */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+
+int main (void)
+{
+ int i = 0;
+ while (!feof(stdin)) {
+ uint64_t a, b;
+ int ret;
+ char *rest = NULL;
+
+ i++;
+ if ((ret = scanf("%" SCNx64 " %" SCNx64 " %m[^\n]\n", &a, &b, &rest)) < 3) {
+ fprintf(stderr,
+ "Syntax error: invalid line %i found in rangefile generation: at least three fields expected, %i converted\n", i, ret);
+ exit(1);
+ }
+
+ printf("0x%018" PRIx64 " %s\n", a+b, rest);
+ free(rest);
+ }
+ exit(0);
+}
@@ -60,10 +60,7 @@ vmlinux_link()
# skip output file argument
shift
- # kallmodsyms needs a linker mapfile that contains original object
- # file names, so cannot use this optimization.
- if { is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; } && \
- ! is_enabled CONFIG_KALLMODSYMS; then
+ if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
# Use vmlinux.o instead of performing the slow LTO link again.
objs=vmlinux.o
libs=
@@ -153,12 +150,31 @@ kallsyms()
# - but sometimes there is a line break after the first field
# - start reading at "Linker script and memory map"
# - stop reading at ".brk"
+ # if there is a vmlinux.o.map and LTO_CLANG or KERNEL_IBT are
+ # turned on, we have used a vmlinux -r'ed .o for linking: use this
+ # as our primary information source, but acquire section addresses
+ # from the (later) linker map we were passed in. This makes things
+ # a bit more complex, since we have to recognize and eliminate
+ # sections elided by the linker, and add together numbers larger
+ # than awk can portably handle.
if is_enabled CONFIG_KALLMODSYMS; then
- ${AWK} '
- /\.o$/ && start==1 { print $(NF-2), $(NF-1), $NF }
- /^Linker script and memory map/ { start = 1 }
- /^\.brk/ { exit(0) }
- ' ${3} | sort > .tmp_vmlinux.ranges
+ if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
+ ${AWK} 'BEGIN { addresses = 1 }
+ /^Linker script and memory map/ { start = 1 }
+ !start { next }
+ { got_section = 0 }
+ /^ \./ { section = $1; got_section = 1; if (NF == 1) { getline }}
+ addresses && got_section && !(section in addrs) { addrs[section] = $2 }
+ !addresses && got_section && section in addrs { print $(NF-2), addrs[section], $(NF-1), $NF }
+ /^\.brk/ || /^\.bss\.\.brk/ { addresses = 0; start = 0; nextfile }
+ ' ${3} vmlinux.o.map | scripts/addaddrs | sort > .tmp_vmlinux.ranges
+ else
+ ${AWK} '
+ start && /\.o$/ { print $(NF-2), $(NF-1), $NF }
+ /^Linker script and memory map/ { start = 1 }
+ /^\.brk/ { exit(0) }
+ ' ${3} | sort > .tmp_vmlinux.ranges
+ fi
fi
# get kallsyms options
The previous commit emits .tmp_vmlinux.ranges, which maps address range/size pairs in vmlinux to the object files which make them up; this is used by kallmodsyms to let us associate symbols with object file names and kernel module names at address-range granularity (i.e., space-efficiently). But the previous commit only works if the final linker runs directly on the input .o files from the kernel build: if an intermediate ld -r is done, the final link emits a mapfile containing only the name of the intermediate ld -r (vmlinux.o), which messes up .tmp_vmlinux.ranges and makes kallmodsyms attribute all symbols to {vmlinux.o} which isn't much use for disambiguation. vmlinux.o has the object file names we need, but the addresses are all wrong so we can't use that either. This commit fixes that by extracting the addresses from the final vmlinux mapfile (or one of the intermediate kallsyms mapfiles) and using them to adjust the address/objfile name pairs extracted from the vmlinux.o mapfile, giving us a ranges map with the right addresses and the right names. It's a bit painful because the addresses are often large numbers, and awk is... not good at handling them (GNU awk can use large integers, but the feature is at risk of removal). So we emit a slightly different file format with a pair of hex values (the address in vmlinux.o and section address from the final mapfile), then pipe it through a tiny new C filter (scripts/addaddrs) whose only purpose is to add those two numbers together! One niggle is that .hot/.cold stuff is no longer correctly attributed to its object file any more -- it seems to not appear in any of the mapfiles at all (only in System.map), so I don't see any way to fix this. (This possibly makes it work with clang LTO too, but I haven't tested it, and if the mapfile format differs it will fail until that's fixed. But this definitely overcomes *one* of the roadblocks preventing clang LTO from working with kallmodsyms.) Signed-off-by: Nick Alcock <nick.alcock@oracle.com> Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com> --- Notes: v10: new. Documentation/dontdiff | 1 + init/Kconfig | 10 ++++++++++ scripts/.gitignore | 1 + scripts/Makefile | 1 + scripts/Makefile.vmlinux_o | 6 +++++- scripts/addaddrs.c | 28 ++++++++++++++++++++++++++++ scripts/link-vmlinux.sh | 34 +++++++++++++++++++++++++--------- 7 files changed, 71 insertions(+), 10 deletions(-) create mode 100644 scripts/addaddrs.c