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![Arnaldo Carvalho de Melo](/assets/img/avatar_default.png)
To have a way to intercept usage of the reference counted struct map. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
368 lines
10 KiB
C
368 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/compiler.h>
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#include <linux/rbtree.h>
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#include <inttypes.h>
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#include <string.h>
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#include <ctype.h>
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#include <stdlib.h>
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#include "dso.h"
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#include "map.h"
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#include "symbol.h"
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#include <internal/lib.h> // page_size
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#include "tests.h"
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#include "debug.h"
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#include "machine.h"
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#define UM(x) map__unmap_ip(kallsyms_map, (x))
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static bool is_ignored_symbol(const char *name, char type)
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{
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/* Symbol names that exactly match to the following are ignored.*/
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static const char * const ignored_symbols[] = {
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/*
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* Symbols which vary between passes. Passes 1 and 2 must have
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* identical symbol lists. The kallsyms_* symbols below are
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* only added after pass 1, they would be included in pass 2
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* when --all-symbols is specified so exclude them to get a
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* stable symbol list.
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*/
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"kallsyms_addresses",
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"kallsyms_offsets",
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"kallsyms_relative_base",
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"kallsyms_num_syms",
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"kallsyms_names",
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"kallsyms_markers",
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"kallsyms_token_table",
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"kallsyms_token_index",
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/* Exclude linker generated symbols which vary between passes */
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"_SDA_BASE_", /* ppc */
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"_SDA2_BASE_", /* ppc */
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NULL
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};
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/* Symbol names that begin with the following are ignored.*/
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static const char * const ignored_prefixes[] = {
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"$", /* local symbols for ARM, MIPS, etc. */
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".L", /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
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"__crc_", /* modversions */
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"__efistub_", /* arm64 EFI stub namespace */
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"__kvm_nvhe_$", /* arm64 local symbols in non-VHE KVM namespace */
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"__kvm_nvhe_.L", /* arm64 local symbols in non-VHE KVM namespace */
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"__AArch64ADRPThunk_", /* arm64 lld */
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"__ARMV5PILongThunk_", /* arm lld */
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"__ARMV7PILongThunk_",
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"__ThumbV7PILongThunk_",
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"__LA25Thunk_", /* mips lld */
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"__microLA25Thunk_",
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NULL
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};
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/* Symbol names that end with the following are ignored.*/
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static const char * const ignored_suffixes[] = {
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"_from_arm", /* arm */
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"_from_thumb", /* arm */
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"_veneer", /* arm */
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NULL
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};
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/* Symbol names that contain the following are ignored.*/
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static const char * const ignored_matches[] = {
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".long_branch.", /* ppc stub */
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".plt_branch.", /* ppc stub */
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NULL
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};
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const char * const *p;
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for (p = ignored_symbols; *p; p++)
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if (!strcmp(name, *p))
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return true;
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for (p = ignored_prefixes; *p; p++)
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if (!strncmp(name, *p, strlen(*p)))
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return true;
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for (p = ignored_suffixes; *p; p++) {
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int l = strlen(name) - strlen(*p);
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if (l >= 0 && !strcmp(name + l, *p))
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return true;
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}
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for (p = ignored_matches; *p; p++) {
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if (strstr(name, *p))
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return true;
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}
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if (type == 'U' || type == 'u')
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return true;
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/* exclude debugging symbols */
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if (type == 'N' || type == 'n')
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return true;
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if (toupper(type) == 'A') {
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/* Keep these useful absolute symbols */
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if (strcmp(name, "__kernel_syscall_via_break") &&
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strcmp(name, "__kernel_syscall_via_epc") &&
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strcmp(name, "__kernel_sigtramp") &&
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strcmp(name, "__gp"))
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return true;
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}
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return false;
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}
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static int test__vmlinux_matches_kallsyms(struct test_suite *test __maybe_unused,
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int subtest __maybe_unused)
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{
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int err = TEST_FAIL;
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struct rb_node *nd;
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struct symbol *sym;
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struct map *kallsyms_map, *vmlinux_map;
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struct map_rb_node *rb_node;
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struct machine kallsyms, vmlinux;
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struct maps *maps;
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u64 mem_start, mem_end;
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bool header_printed;
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/*
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* Step 1:
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*
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* Init the machines that will hold kernel, modules obtained from
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* both vmlinux + .ko files and from /proc/kallsyms split by modules.
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*/
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machine__init(&kallsyms, "", HOST_KERNEL_ID);
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machine__init(&vmlinux, "", HOST_KERNEL_ID);
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maps = machine__kernel_maps(&vmlinux);
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/*
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* Step 2:
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*
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* Create the kernel maps for kallsyms and the DSO where we will then
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* load /proc/kallsyms. Also create the modules maps from /proc/modules
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* and find the .ko files that match them in /lib/modules/`uname -r`/.
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*/
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if (machine__create_kernel_maps(&kallsyms) < 0) {
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pr_debug("machine__create_kernel_maps failed");
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err = TEST_SKIP;
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goto out;
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}
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/*
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* Step 3:
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*
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* Load and split /proc/kallsyms into multiple maps, one per module.
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* Do not use kcore, as this test was designed before kcore support
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* and has parts that only make sense if using the non-kcore code.
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* XXX: extend it to stress the kcorre code as well, hint: the list
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* of modules extracted from /proc/kcore, in its current form, can't
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* be compacted against the list of modules found in the "vmlinux"
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* code and with the one got from /proc/modules from the "kallsyms" code.
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*/
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if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
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pr_debug("machine__load_kallsyms failed");
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err = TEST_SKIP;
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goto out;
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}
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/*
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* Step 4:
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*
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* kallsyms will be internally on demand sorted by name so that we can
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* find the reference relocation * symbol, i.e. the symbol we will use
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* to see if the running kernel was relocated by checking if it has the
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* same value in the vmlinux file we load.
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*/
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kallsyms_map = machine__kernel_map(&kallsyms);
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/*
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* Step 5:
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*
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* Now repeat step 2, this time for the vmlinux file we'll auto-locate.
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*/
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if (machine__create_kernel_maps(&vmlinux) < 0) {
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pr_info("machine__create_kernel_maps failed");
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goto out;
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}
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vmlinux_map = machine__kernel_map(&vmlinux);
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/*
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* Step 6:
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*
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* Locate a vmlinux file in the vmlinux path that has a buildid that
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* matches the one of the running kernel.
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*
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* While doing that look if we find the ref reloc symbol, if we find it
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* we'll have its ref_reloc_symbol.unrelocated_addr and then
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* maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
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* to fixup the symbols.
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*/
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if (machine__load_vmlinux_path(&vmlinux) <= 0) {
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pr_info("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
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err = TEST_SKIP;
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goto out;
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}
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err = 0;
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/*
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* Step 7:
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*
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* Now look at the symbols in the vmlinux DSO and check if we find all of them
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* in the kallsyms dso. For the ones that are in both, check its names and
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* end addresses too.
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*/
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map__for_each_symbol(vmlinux_map, sym, nd) {
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struct symbol *pair, *first_pair;
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sym = rb_entry(nd, struct symbol, rb_node);
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if (sym->start == sym->end)
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continue;
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mem_start = map__unmap_ip(vmlinux_map, sym->start);
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mem_end = map__unmap_ip(vmlinux_map, sym->end);
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first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
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pair = first_pair;
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if (pair && UM(pair->start) == mem_start) {
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next_pair:
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if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
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/*
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* kallsyms don't have the symbol end, so we
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* set that by using the next symbol start - 1,
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* in some cases we get this up to a page
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* wrong, trace_kmalloc when I was developing
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* this code was one such example, 2106 bytes
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* off the real size. More than that and we
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* _really_ have a problem.
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*/
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s64 skew = mem_end - UM(pair->end);
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if (llabs(skew) >= page_size)
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pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
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mem_start, sym->name, mem_end,
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UM(pair->end));
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/*
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* Do not count this as a failure, because we
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* could really find a case where it's not
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* possible to get proper function end from
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* kallsyms.
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*/
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continue;
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} else {
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pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
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if (pair) {
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if (UM(pair->start) == mem_start)
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goto next_pair;
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pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
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mem_start, sym->name, pair->name);
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} else {
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pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
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mem_start, sym->name, first_pair->name);
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}
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continue;
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}
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} else if (mem_start == map__end(kallsyms.vmlinux_map)) {
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/*
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* Ignore aliases to _etext, i.e. to the end of the kernel text area,
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* such as __indirect_thunk_end.
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*/
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continue;
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} else if (is_ignored_symbol(sym->name, sym->type)) {
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/*
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* Ignore hidden symbols, see scripts/kallsyms.c for the details
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*/
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continue;
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} else {
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pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
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mem_start, sym->name);
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}
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err = -1;
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}
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if (verbose <= 0)
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goto out;
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header_printed = false;
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maps__for_each_entry(maps, rb_node) {
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struct map *map = rb_node->map;
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struct dso *dso = map__dso(map);
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/*
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* If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
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* the kernel will have the path for the vmlinux file being used,
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* so use the short name, less descriptive but the same ("[kernel]" in
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* both cases.
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*/
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struct map *pair = maps__find_by_name(kallsyms.kmaps, (dso->kernel ?
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dso->short_name :
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dso->name));
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if (pair) {
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map__set_priv(pair, 1);
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} else {
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if (!header_printed) {
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pr_info("WARN: Maps only in vmlinux:\n");
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header_printed = true;
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}
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map__fprintf(map, stderr);
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}
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}
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header_printed = false;
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maps__for_each_entry(maps, rb_node) {
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struct map *pair, *map = rb_node->map;
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mem_start = map__unmap_ip(vmlinux_map, map__start(map));
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mem_end = map__unmap_ip(vmlinux_map, map__end(map));
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pair = maps__find(kallsyms.kmaps, mem_start);
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if (pair == NULL || map__priv(pair))
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continue;
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if (map__start(pair) == mem_start) {
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struct dso *dso = map__dso(map);
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if (!header_printed) {
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pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
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header_printed = true;
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}
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pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
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map__start(map), map__end(map), map__pgoff(map), dso->name);
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if (mem_end != map__end(pair))
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pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
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map__start(pair), map__end(pair), map__pgoff(pair));
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pr_info(" %s\n", dso->name);
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map__set_priv(pair, 1);
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}
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}
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header_printed = false;
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maps = machine__kernel_maps(&kallsyms);
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maps__for_each_entry(maps, rb_node) {
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struct map *map = rb_node->map;
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if (!map__priv(map)) {
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if (!header_printed) {
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pr_info("WARN: Maps only in kallsyms:\n");
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header_printed = true;
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}
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map__fprintf(map, stderr);
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}
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}
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out:
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machine__exit(&kallsyms);
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machine__exit(&vmlinux);
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return err;
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}
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DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);
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