44ca9341f6
perf now uses an offset from _text/_stext for kretprobes if the kernel supports it, rather than the actual function name. As such, let's choose the LEP for powerpc ABIv2 so as to ensure the probe gets hit. Do it only if the kernel supports specifying offsets with kretprobes. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/7445b5334673ef5404ac1d12609bad4d73d2b567.1488961018.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
132 lines
3.1 KiB
C
132 lines
3.1 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation.
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*
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* Copyright (C) 2015 Naveen N. Rao, IBM Corporation
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*/
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#include "debug.h"
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#include "symbol.h"
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#include "map.h"
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#include "probe-event.h"
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#include "probe-file.h"
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#ifdef HAVE_LIBELF_SUPPORT
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bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
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{
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return ehdr.e_type == ET_EXEC ||
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ehdr.e_type == ET_REL ||
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ehdr.e_type == ET_DYN;
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}
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#endif
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#if !defined(_CALL_ELF) || _CALL_ELF != 2
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int arch__choose_best_symbol(struct symbol *syma,
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struct symbol *symb __maybe_unused)
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{
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char *sym = syma->name;
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/* Skip over any initial dot */
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if (*sym == '.')
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sym++;
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/* Avoid "SyS" kernel syscall aliases */
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if (strlen(sym) >= 3 && !strncmp(sym, "SyS", 3))
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return SYMBOL_B;
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if (strlen(sym) >= 10 && !strncmp(sym, "compat_SyS", 10))
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return SYMBOL_B;
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return SYMBOL_A;
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}
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/* Allow matching against dot variants */
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int arch__compare_symbol_names(const char *namea, const char *nameb)
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{
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/* Skip over initial dot */
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if (*namea == '.')
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namea++;
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if (*nameb == '.')
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nameb++;
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return strcmp(namea, nameb);
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}
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#endif
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#if defined(_CALL_ELF) && _CALL_ELF == 2
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#ifdef HAVE_LIBELF_SUPPORT
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void arch__sym_update(struct symbol *s, GElf_Sym *sym)
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{
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s->arch_sym = sym->st_other;
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}
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#endif
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#define PPC64LE_LEP_OFFSET 8
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void arch__fix_tev_from_maps(struct perf_probe_event *pev,
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struct probe_trace_event *tev, struct map *map,
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struct symbol *sym)
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{
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int lep_offset;
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/*
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* When probing at a function entry point, we normally always want the
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* LEP since that catches calls to the function through both the GEP and
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* the LEP. Hence, we would like to probe at an offset of 8 bytes if
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* the user only specified the function entry.
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*
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* However, if the user specifies an offset, we fall back to using the
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* GEP since all userspace applications (objdump/readelf) show function
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* disassembly with offsets from the GEP.
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*/
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if (pev->point.offset || !map || !sym)
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return;
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/* For kretprobes, add an offset only if the kernel supports it */
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if (!pev->uprobes && pev->point.retprobe) {
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#ifdef HAVE_LIBELF_SUPPORT
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if (!kretprobe_offset_is_supported())
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#endif
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return;
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}
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lep_offset = PPC64_LOCAL_ENTRY_OFFSET(sym->arch_sym);
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if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS)
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tev->point.offset += PPC64LE_LEP_OFFSET;
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else if (lep_offset) {
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if (pev->uprobes)
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tev->point.address += lep_offset;
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else
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tev->point.offset += lep_offset;
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}
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}
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#ifdef HAVE_LIBELF_SUPPORT
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void arch__post_process_probe_trace_events(struct perf_probe_event *pev,
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int ntevs)
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{
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struct probe_trace_event *tev;
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struct map *map;
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struct symbol *sym = NULL;
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struct rb_node *tmp;
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int i = 0;
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map = get_target_map(pev->target, pev->uprobes);
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if (!map || map__load(map) < 0)
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return;
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for (i = 0; i < ntevs; i++) {
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tev = &pev->tevs[i];
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map__for_each_symbol(map, sym, tmp) {
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if (map->unmap_ip(map, sym->start) == tev->point.address)
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arch__fix_tev_from_maps(pev, tev, map, sym);
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}
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}
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}
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#endif /* HAVE_LIBELF_SUPPORT */
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#endif
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