cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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unwind-libdw.c (6686B)


      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/compiler.h>
      3#include <elfutils/libdw.h>
      4#include <elfutils/libdwfl.h>
      5#include <inttypes.h>
      6#include <errno.h>
      7#include "debug.h"
      8#include "dso.h"
      9#include "unwind.h"
     10#include "unwind-libdw.h"
     11#include "machine.h"
     12#include "map.h"
     13#include "symbol.h"
     14#include "thread.h"
     15#include <linux/types.h>
     16#include <linux/zalloc.h>
     17#include "event.h"
     18#include "perf_regs.h"
     19#include "callchain.h"
     20
     21static char *debuginfo_path;
     22
     23static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata,
     24			    const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused,
     25			    const char *file_name, const char *debuglink_file __maybe_unused,
     26			    GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name)
     27{
     28	const struct dso *dso = *userdata;
     29
     30	assert(dso);
     31	if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename))
     32		*debuginfo_file_name = strdup(dso->symsrc_filename);
     33	return -1;
     34}
     35
     36static const Dwfl_Callbacks offline_callbacks = {
     37	.find_debuginfo		= __find_debuginfo,
     38	.debuginfo_path		= &debuginfo_path,
     39	.section_address	= dwfl_offline_section_address,
     40	// .find_elf is not set as we use dwfl_report_elf() instead.
     41};
     42
     43static int __report_module(struct addr_location *al, u64 ip,
     44			    struct unwind_info *ui)
     45{
     46	Dwfl_Module *mod;
     47	struct dso *dso = NULL;
     48	/*
     49	 * Some callers will use al->sym, so we can't just use the
     50	 * cheaper thread__find_map() here.
     51	 */
     52	thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
     53
     54	if (al->map)
     55		dso = al->map->dso;
     56
     57	if (!dso)
     58		return 0;
     59
     60	mod = dwfl_addrmodule(ui->dwfl, ip);
     61	if (mod) {
     62		Dwarf_Addr s;
     63
     64		dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
     65		if (s != al->map->start - al->map->pgoff)
     66			mod = 0;
     67	}
     68
     69	if (!mod)
     70		mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1,
     71				      al->map->start - al->map->pgoff, false);
     72	if (!mod) {
     73		char filename[PATH_MAX];
     74
     75		if (dso__build_id_filename(dso, filename, sizeof(filename), false))
     76			mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1,
     77					      al->map->start - al->map->pgoff, false);
     78	}
     79
     80	if (mod) {
     81		void **userdatap;
     82
     83		dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL);
     84		*userdatap = dso;
     85	}
     86
     87	return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
     88}
     89
     90static int report_module(u64 ip, struct unwind_info *ui)
     91{
     92	struct addr_location al;
     93
     94	return __report_module(&al, ip, ui);
     95}
     96
     97/*
     98 * Store all entries within entries array,
     99 * we will process it after we finish unwind.
    100 */
    101static int entry(u64 ip, struct unwind_info *ui)
    102
    103{
    104	struct unwind_entry *e = &ui->entries[ui->idx++];
    105	struct addr_location al;
    106
    107	if (__report_module(&al, ip, ui))
    108		return -1;
    109
    110	e->ip	  = ip;
    111	e->ms.maps = al.maps;
    112	e->ms.map = al.map;
    113	e->ms.sym = al.sym;
    114
    115	pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
    116		 al.sym ? al.sym->name : "''",
    117		 ip,
    118		 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
    119	return 0;
    120}
    121
    122static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
    123{
    124	/* We want only single thread to be processed. */
    125	if (*thread_argp != NULL)
    126		return 0;
    127
    128	*thread_argp = arg;
    129	return dwfl_pid(dwfl);
    130}
    131
    132static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
    133			  Dwarf_Word *data)
    134{
    135	struct addr_location al;
    136	ssize_t size;
    137
    138	if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
    139		pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
    140		return -1;
    141	}
    142
    143	if (!al.map->dso)
    144		return -1;
    145
    146	size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
    147				   addr, (u8 *) data, sizeof(*data));
    148
    149	return !(size == sizeof(*data));
    150}
    151
    152static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
    153			void *arg)
    154{
    155	struct unwind_info *ui = arg;
    156	struct stack_dump *stack = &ui->sample->user_stack;
    157	u64 start, end;
    158	int offset;
    159	int ret;
    160
    161	ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
    162	if (ret)
    163		return false;
    164
    165	end = start + stack->size;
    166
    167	/* Check overflow. */
    168	if (addr + sizeof(Dwarf_Word) < addr)
    169		return false;
    170
    171	if (addr < start || addr + sizeof(Dwarf_Word) > end) {
    172		ret = access_dso_mem(ui, addr, result);
    173		if (ret) {
    174			pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
    175				 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
    176				addr, start, end);
    177			return false;
    178		}
    179		return true;
    180	}
    181
    182	offset  = addr - start;
    183	*result = *(Dwarf_Word *)&stack->data[offset];
    184	pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
    185		 addr, (unsigned long)*result, offset);
    186	return true;
    187}
    188
    189static const Dwfl_Thread_Callbacks callbacks = {
    190	.next_thread		= next_thread,
    191	.memory_read		= memory_read,
    192	.set_initial_registers	= libdw__arch_set_initial_registers,
    193};
    194
    195static int
    196frame_callback(Dwfl_Frame *state, void *arg)
    197{
    198	struct unwind_info *ui = arg;
    199	Dwarf_Addr pc;
    200	bool isactivation;
    201
    202	if (!dwfl_frame_pc(state, &pc, NULL)) {
    203		if (!ui->best_effort)
    204			pr_err("%s", dwfl_errmsg(-1));
    205		return DWARF_CB_ABORT;
    206	}
    207
    208	// report the module before we query for isactivation
    209	report_module(pc, ui);
    210
    211	if (!dwfl_frame_pc(state, &pc, &isactivation)) {
    212		if (!ui->best_effort)
    213			pr_err("%s", dwfl_errmsg(-1));
    214		return DWARF_CB_ABORT;
    215	}
    216
    217	if (!isactivation)
    218		--pc;
    219
    220	return entry(pc, ui) || !(--ui->max_stack) ?
    221	       DWARF_CB_ABORT : DWARF_CB_OK;
    222}
    223
    224int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
    225			struct thread *thread,
    226			struct perf_sample *data,
    227			int max_stack,
    228			bool best_effort)
    229{
    230	struct unwind_info *ui, ui_buf = {
    231		.sample		= data,
    232		.thread		= thread,
    233		.machine	= thread->maps->machine,
    234		.cb		= cb,
    235		.arg		= arg,
    236		.max_stack	= max_stack,
    237		.best_effort    = best_effort
    238	};
    239	Dwarf_Word ip;
    240	int err = -EINVAL, i;
    241
    242	if (!data->user_regs.regs)
    243		return -EINVAL;
    244
    245	ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
    246	if (!ui)
    247		return -ENOMEM;
    248
    249	*ui = ui_buf;
    250
    251	ui->dwfl = dwfl_begin(&offline_callbacks);
    252	if (!ui->dwfl)
    253		goto out;
    254
    255	err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
    256	if (err)
    257		goto out;
    258
    259	err = report_module(ip, ui);
    260	if (err)
    261		goto out;
    262
    263	err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
    264	if (err)
    265		goto out;
    266
    267	err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
    268
    269	if (err && ui->max_stack != max_stack)
    270		err = 0;
    271
    272	/*
    273	 * Display what we got based on the order setup.
    274	 */
    275	for (i = 0; i < ui->idx && !err; i++) {
    276		int j = i;
    277
    278		if (callchain_param.order == ORDER_CALLER)
    279			j = ui->idx - i - 1;
    280
    281		err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
    282	}
    283
    284 out:
    285	if (err)
    286		pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
    287
    288	dwfl_end(ui->dwfl);
    289	free(ui);
    290	return 0;
    291}