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https://sourceware.org/git/binutils-gdb.git
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cb19713281
Running gdbserver under Valgrind I get:
==26925== Conditional jump or move depends on uninitialised value(s)
==26925== at 0x473E7F: i387_cache_to_xsave(regcache*, void*) (i387-fp.c:579)
==26925== by 0x46E3ED: x86_fill_xstateregset(regcache*, void*) (linux-x86-low.c:418)
==26925== by 0x45E747: regsets_store_inferior_registers(regsets_info*, regcache*) (linux-low.c:5456)
==26925== by 0x45EEF8: linux_store_registers(regcache*, int) (linux-low.c:5731)
==26925== by 0x426441: regcache_invalidate_thread(thread_info*) (regcache.c:89)
==26925== by 0x45CCAF: linux_resume_one_lwp_throw(lwp_info*, int, int, siginfo_t*) (linux-low.c:4447)
==26925== by 0x45CE2A: linux_resume_one_lwp(lwp_info*, int, int, siginfo_t*) (linux-low.c:4519)
==26925== by 0x45E17C: proceed_one_lwp(thread_info*, lwp_info*) (linux-low.c:5216)
==26925== by 0x45DC81: linux_resume_one_thread(thread_info*, bool) (linux-low.c:5031)
==26925== by 0x45DD34: linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}::operator()(thread_info*) const (linux-low.c:5095)
==26925== by 0x462907: void for_each_thread<linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}>(linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}) (gdbthread.h:150)
==26925== by 0x45DE62: linux_resume(thread_resume*, unsigned long) (linux-low.c:5093)
==26925==
==26925== Conditional jump or move depends on uninitialised value(s)
==26925== at 0x473EBD: i387_cache_to_xsave(regcache*, void*) (i387-fp.c:586)
==26925== by 0x46E3ED: x86_fill_xstateregset(regcache*, void*) (linux-x86-low.c:418)
==26925== by 0x45E747: regsets_store_inferior_registers(regsets_info*, regcache*) (linux-low.c:5456)
==26925== by 0x45EEF8: linux_store_registers(regcache*, int) (linux-low.c:5731)
==26925== by 0x426441: regcache_invalidate_thread(thread_info*) (regcache.c:89)
==26925== by 0x45CCAF: linux_resume_one_lwp_throw(lwp_info*, int, int, siginfo_t*) (linux-low.c:4447)
==26925== by 0x45CE2A: linux_resume_one_lwp(lwp_info*, int, int, siginfo_t*) (linux-low.c:4519)
==26925== by 0x45E17C: proceed_one_lwp(thread_info*, lwp_info*) (linux-low.c:5216)
==26925== by 0x45DC81: linux_resume_one_thread(thread_info*, bool) (linux-low.c:5031)
==26925== by 0x45DD34: linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}::operator()(thread_info*) const (linux-low.c:5095)
==26925== by 0x462907: void for_each_thread<linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}>(linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}) (gdbthread.h:150)
==26925== by 0x45DE62: linux_resume(thread_resume*, unsigned long) (linux-low.c:5093)
The problem is a type/width mismatch in code like this, in
gdbserver/i387-fp.c:
/* Some registers are 16-bit. */
collect_register_by_name (regcache, "fctrl", &val);
fp->fctrl = val;
In the above code:
#1 - 'val' is a 64-bit unsigned long.
#2 - "fctrl" is 32-bit in the register cache, thus half of 'val' is
left uninitialized by collect_register_by_name, which works with
an untyped raw buffer output (i.e., void*).
#3 - fp->fctrl is an unsigned short (16-bit). For some such
registers we're masking off the uninitialized bits with 0xffff,
but not in all cases.
We end up in such a fragile situation because
collect_registers_by_name works with an untyped output buffer pointer,
making it easy to pass a pointer to a variable of the wrong size.
Fix this by using regcache_raw_get_unsigned instead (actually a new
regcache_raw_get_unsigned_by_name wrapper), which always returns a
zero-extended ULONGEST register value. It ends up simplifying the
i387-tdep.c code a bit, even.
gdb/gdbserver/ChangeLog:
2018-07-11 Pedro Alves <palves@redhat.com>
* i387-fp.c (i387_cache_to_fsave, cache_to_fxsave)
(i387_cache_to_xsave): Use regcache_raw_get_unsigned_by_name
instead of collect_register_by_name.
* regcache.c (regcache_raw_get_unsigned_by_name): New.
* regcache.h (regcache_raw_get_unsigned_by_name): New.
142 lines
4.6 KiB
C
142 lines
4.6 KiB
C
/* Register support routines for the remote server for GDB.
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Copyright (C) 2001-2018 Free Software Foundation, Inc.
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This file is part of GDB.
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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 as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef REGCACHE_H
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#define REGCACHE_H
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#include "common-regcache.h"
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struct thread_info;
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struct target_desc;
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/* The data for the register cache. Note that we have one per
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inferior; this is primarily for simplicity, as the performance
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benefit is minimal. */
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struct regcache : public reg_buffer_common
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{
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/* The regcache's target description. */
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const struct target_desc *tdesc = nullptr;
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/* Whether the REGISTERS buffer's contents are valid. If false, we
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haven't fetched the registers from the target yet. Not that this
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register cache is _not_ pass-through, unlike GDB's. Note that
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"valid" here is unrelated to whether the registers are available
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in a traceframe. For that, check REGISTER_STATUS below. */
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int registers_valid = 0;
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int registers_owned = 0;
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unsigned char *registers = nullptr;
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#ifndef IN_PROCESS_AGENT
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/* One of REG_UNAVAILBLE or REG_VALID. */
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unsigned char *register_status = nullptr;
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#endif
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/* See common/common-regcache.h. */
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enum register_status get_register_status (int regnum) const override;
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/* See common/common-regcache.h. */
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void raw_supply (int regnum, const void *buf) override;
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/* See common/common-regcache.h. */
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void raw_collect (int regnum, void *buf) const override;
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/* See common/common-regcache.h. */
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bool raw_compare (int regnum, const void *buf, int offset) const override;
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};
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struct regcache *init_register_cache (struct regcache *regcache,
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const struct target_desc *tdesc,
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unsigned char *regbuf);
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void regcache_cpy (struct regcache *dst, struct regcache *src);
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/* Create a new register cache for INFERIOR. */
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struct regcache *new_register_cache (const struct target_desc *tdesc);
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struct regcache *get_thread_regcache (struct thread_info *thread, int fetch);
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/* Release all memory associated with the register cache for INFERIOR. */
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void free_register_cache (struct regcache *regcache);
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/* Invalidate cached registers for one thread. */
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void regcache_invalidate_thread (struct thread_info *);
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/* Invalidate cached registers for all threads of the given process. */
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void regcache_invalidate_pid (int pid);
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/* Invalidate cached registers for all threads of the current
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process. */
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void regcache_invalidate (void);
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/* Invalidate and release the register cache of all threads of the
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current process. */
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void regcache_release (void);
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/* Convert all registers to a string in the currently specified remote
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format. */
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void registers_to_string (struct regcache *regcache, char *buf);
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/* Convert a string to register values and fill our register cache. */
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void registers_from_string (struct regcache *regcache, char *buf);
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/* For regcache_read_pc see common/common-regcache.h. */
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void regcache_write_pc (struct regcache *regcache, CORE_ADDR pc);
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int register_cache_size (const struct target_desc *tdesc);
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int register_size (const struct target_desc *tdesc, int n);
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int find_regno (const struct target_desc *tdesc, const char *name);
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void supply_register (struct regcache *regcache, int n, const void *buf);
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void supply_register_zeroed (struct regcache *regcache, int n);
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void supply_register_by_name (struct regcache *regcache,
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const char *name, const void *buf);
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void supply_register_by_name_zeroed (struct regcache *regcache,
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const char *name);
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void supply_regblock (struct regcache *regcache, const void *buf);
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void collect_register (struct regcache *regcache, int n, void *buf);
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void collect_register_as_string (struct regcache *regcache, int n, char *buf);
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void collect_register_by_name (struct regcache *regcache,
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const char *name, void *buf);
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/* Read a raw register as an unsigned integer. Convenience wrapper
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around regcache_raw_get_unsigned that takes a register name instead
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of a register number. */
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ULONGEST regcache_raw_get_unsigned_by_name (struct regcache *regcache,
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const char *name);
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#endif /* REGCACHE_H */
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