1#!/bin/bash 2# SPDX-License-Identifier: GPL-2.0 3# 4# sympos for vmlinux, which is resolved differently from sympos for a module. 5# 6# A module's .ko preserves symbol table order, so klp diff can count -- that is 7# what test-sympos covers. vmlinux cannot be counted: the final link reorders 8# sub-sections, so the order in vmlinux.o is not the order the running kernel 9# has. klp diff bridges that with .klp.symid, a table of { id, address } 10# emitted into vmlinux.o whose addresses the linker resolves, read back out of 11# the linked vmlinux. 12# 13# Getting it wrong points the relocation at a different symbol of the same 14# name. Nothing fails to build or load; the patched code uses the wrong 15# object. 16# 17# The fixture is arranged so the two answers differ: the static that comes 18# first in the symbol table is placed at the *higher* address, so counting 19# gives 1 and reading the linked image gives 2. Without that, both paths agree 20# and the test cannot tell them apart. 21 22. "$(dirname "$0")/../lib.sh" 23 24setup 25 26# use_a's static sorts last by section name, use_b's first. Only use_a is 27# patched, so exactly one sympos comes out. 28build_one sympos_vmlinux.c orig_a.o -DFUNC_NAME=use_a -DVARSEC='".data.zzz"' 29build_one sympos_vmlinux.c patched_a.o -DFUNC_NAME=use_a -DVARSEC='".data.zzz"' -DPATCHED 30build_one sympos_vmlinux.c b.o -DFUNC_NAME=use_b -DVARSEC='".data.aaa"' -DNO_MODINFO 31 32make_vmlinux_pair "$workdir/orig_a.o" "$workdir/b.o" \ 33 -- "$workdir/patched_a.o" "$workdir/b.o" 34 35[ "$(count_input_symbols vmlinux.o dup_counter)" = 2 ] || 36 fail "fixture did not produce two dup_counter symbols" 37has_input_section vmlinux.o .klp.symid || 38 fail "objtool --klp-symids emitted no .klp.symid table" 39has_input_section vmlinux .klp.symid || 40 fail ".klp.symid did not survive the link" 41 42# The premise: symbol table order and address order must disagree, or the test 43# proves nothing. 44first_addr="$(in_symbols vmlinux | awk '$8 == "dup_counter" { print $2; exit }')" 45low_addr="$(in_symbols vmlinux | awk '$8 == "dup_counter" { print $2 }' | sort | head -1)" 46[ "$first_addr" != "$low_addr" ] || 47 probe_skip "linker did not reorder the two statics" 48 49assert_input_symbol dup_counter 50run_diff 51 52# Address order says 2. Counting symbol table order would say 1. 53assert_klp_sympos dup_counter 2 54out_symbols | grep -q 'dup_counter,1' && 55 fail "sympos 1 emitted: counted symbol table order instead of reading the linked vmlinux" 56 57pass "vmlinux sympos taken from the linked image, not from symbol table order" 58