/* * Copyright (C) 2015 Josh Poimboeuf * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . */ /* * This file reads all the special sections which have alternate instructions * which can be patched in or redirected to at runtime. */ #include #include #include "special.h" #include "warn.h" #define EX_ENTRY_SIZE 12 #define EX_ORIG_OFFSET 0 #define EX_NEW_OFFSET 4 #define JUMP_ENTRY_SIZE 24 #define JUMP_ORIG_OFFSET 0 #define JUMP_NEW_OFFSET 8 #define ALT_ENTRY_SIZE 13 #define ALT_ORIG_OFFSET 0 #define ALT_NEW_OFFSET 4 #define ALT_FEATURE_OFFSET 8 #define ALT_ORIG_LEN_OFFSET 10 #define ALT_NEW_LEN_OFFSET 11 #define X86_FEATURE_POPCNT (4*32+23) struct special_entry { const char *sec; bool group, jump_or_nop; unsigned char size, orig, new; unsigned char orig_len, new_len; /* group only */ unsigned char feature; /* ALTERNATIVE macro CPU feature */ }; struct special_entry entries[] = { { .sec = ".altinstructions", .group = true, .size = ALT_ENTRY_SIZE, .orig = ALT_ORIG_OFFSET, .orig_len = ALT_ORIG_LEN_OFFSET, .new = ALT_NEW_OFFSET, .new_len = ALT_NEW_LEN_OFFSET, .feature = ALT_FEATURE_OFFSET, }, { .sec = "__jump_table", .jump_or_nop = true, .size = JUMP_ENTRY_SIZE, .orig = JUMP_ORIG_OFFSET, .new = JUMP_NEW_OFFSET, }, { .sec = "__ex_table", .size = EX_ENTRY_SIZE, .orig = EX_ORIG_OFFSET, .new = EX_NEW_OFFSET, }, {}, }; static int get_alt_entry(struct elf *elf, struct special_entry *entry, struct section *sec, int idx, struct special_alt *alt) { struct rela *orig_rela, *new_rela; unsigned long offset; offset = idx * entry->size; alt->group = entry->group; alt->jump_or_nop = entry->jump_or_nop; if (alt->group) { alt->orig_len = *(unsigned char *)(sec->data + offset + entry->orig_len); alt->new_len = *(unsigned char *)(sec->data + offset + entry->new_len); } if (entry->feature) { unsigned short feature; feature = *(unsigned short *)(sec->data + offset + entry->feature); /* * It has been requested that we don't validate the !POPCNT * feature path which is a "very very small percentage of * machines". */ if (feature == X86_FEATURE_POPCNT) alt->skip_orig = true; } orig_rela = find_rela_by_dest(sec, offset + entry->orig); if (!orig_rela) { WARN_FUNC("can't find orig rela", sec, offset + entry->orig); return -1; } if (orig_rela->sym->type != STT_SECTION) { WARN_FUNC("don't know how to handle non-section rela symbol %s", sec, offset + entry->orig, orig_rela->sym->name); return -1; } alt->orig_sec = orig_rela->sym->sec; alt->orig_off = orig_rela->addend; if (!entry->group || alt->new_len) { new_rela = find_rela_by_dest(sec, offset + entry->new); if (!new_rela) { WARN_FUNC("can't find new rela", sec, offset + entry->new); return -1; } alt->new_sec = new_rela->sym->sec; alt->new_off = (unsigned int)new_rela->addend; /* _ASM_EXTABLE_EX hack */ if (alt->new_off >= 0x7ffffff0) alt->new_off -= 0x7ffffff0; } return 0; } /* * Read all the special sections and create a list of special_alt structs which * describe all the alternate instructions which can be patched in or * redirected to at runtime. */ int special_get_alts(struct elf *elf, struct list_head *alts) { struct special_entry *entry; struct section *sec; unsigned int nr_entries; struct special_alt *alt; int idx, ret; INIT_LIST_HEAD(alts); for (entry = entries; entry->sec; entry++) { sec = find_section_by_name(elf, entry->sec); if (!sec) continue; if (sec->len % entry->size != 0) { WARN("%s size not a multiple of %d", sec->name, entry->size); return -1; } nr_entries = sec->len / entry->size; for (idx = 0; idx < nr_entries; idx++) { alt = malloc(sizeof(*alt)); if (!alt) { WARN("malloc failed"); return -1; } memset(alt, 0, sizeof(*alt)); ret = get_alt_entry(elf, entry, sec, idx, alt); if (ret) return ret; list_add_tail(&alt->list, alts); } } return 0; }
authorThomas Gleixner <tglx@linutronix.de>2017-01-31 09:37:34 +0100
committerThomas Gleixner <tglx@linutronix.de>2017-01-31 21:47:58 +0100
commit0becc0ae5b42828785b589f686725ff5bc3b9b25 (patch)
treebe6d0e1f37c38ed0a7dd5da2d4b1e93f0fb43101 /tools/perf/util/debug.h
parent24c2503255d35c269b67162c397a1a1c1e02f6ce (diff)
x86/mce: Make timer handling more robust
Erik reported that on a preproduction hardware a CMCI storm triggers the BUG_ON in add_timer_on(). The reason is that the per CPU MCE timer is started by the CMCI logic before the MCE CPU hotplug callback starts the timer with add_timer_on(). So the timer is already queued which triggers the BUG. Using add_timer_on() is pretty pointless in this code because the timer is strictlty per CPU, initialized as pinned and all operations which arm the timer happen on the CPU to which the timer belongs. Simplify the whole machinery by using mod_timer() instead of add_timer_on() which avoids the problem because mod_timer() can handle already queued timers. Use __start_timer() everywhere so the earliest armed expiry time is preserved. Reported-by: Erik Veijola <erik.veijola@intel.com> Tested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@alien8.de> Cc: Tony Luck <tony.luck@intel.com> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701310936080.3457@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'tools/perf/util/debug.h')