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Recently a feature called "return address signing" has been added to GCC to prevent stack smash stack on AArch64. For details please refer: https://gcc.gnu.org/ml/gcc-patches/2017-01/msg00376.html GDB needs to be aware of this feature so it can restore the original return address which is critical for unwinding. On compiler side, whenever return address, i.e. LR register, is mangled or restored by hardware instruction, compiler is expected to generate a DW_CFA_AARCH64_negate_ra_state to toggle return address signing status. DW_CFA_AARCH64_negate_ra_state is using the same CFI number and therefore need to be multiplexed with DW_CFA_GNU_window_save which was designed for SPARC. A new gdbarch method "execute_dwarf_cfa_vendor_op" is introduced by this patch. It's parameters has been restricted to those only needed by SPARC and AArch64 for multiplexing DW_CFA_GNU_window_save which is a CFI operation takes none operand. Should any further DWARF CFI operation want to be multiplexed in the future, the parameter list can be extended. Below is the current function prototype. typedef int (gdbarch_execute_dwarf_cfa_vendor_op_ftype) (struct gdbarch *gdbarch, gdb_byte op, struct dwarf2_frame_state *fs); DW_CFA_GNU_window_save support for SPARC is migrated to this new gdbarch method by this patch. gdb/ * gdbarch.sh: New gdbarch method execute_dwarf_cfa_vendor_op. * gdbarch.c: Regenerated. * gdbarch.h: Regenerated. * dwarf2-frame.c (dwarf2_frame_state_alloc_regs): Made the visibility external. (execute_cfa_program): Call execute_dwarf_cfa_vendor_op for CFI between DW_CFA_lo_user and DW_CFA_high_user inclusive. (enum cfa_how_kind): Move to ... (struct dwarf2_frame_state_reg_info): Likewise. (struct dwarf2_frame_state): Likewise. * dwarf2-frame.h: ... here. (dwarf2_frame_state_alloc_regs): New declaration. * sparc-tdep.c (sparc_execute_dwarf_cfa_vendor_op): New function. (sparc32_gdbarch_init): Register execute_dwarf_cfa_vendor_op hook.
204 lines
6.3 KiB
C
204 lines
6.3 KiB
C
/* Frame unwinder for frames with DWARF Call Frame Information.
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Copyright (C) 2003-2017 Free Software Foundation, Inc.
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Contributed by Mark Kettenis.
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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 DWARF2_FRAME_H
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#define DWARF2_FRAME_H 1
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struct gdbarch;
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struct objfile;
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struct frame_info;
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struct dwarf2_per_cu_data;
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struct agent_expr;
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struct axs_value;
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/* Register rule. */
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enum dwarf2_frame_reg_rule
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{
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/* Make certain that 0 maps onto the correct enum value; the
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corresponding structure is being initialized using memset zero.
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This indicates that CFI didn't provide any information at all
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about a register, leaving how to obtain its value totally
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unspecified. */
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DWARF2_FRAME_REG_UNSPECIFIED = 0,
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/* The term "undefined" comes from the DWARF2 CFI spec which this
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code is moddeling; it indicates that the register's value is
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"undefined". GCC uses the less formal term "unsaved". Its
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definition is a combination of REG_UNDEFINED and REG_UNSPECIFIED.
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The failure to differentiate the two helps explain a few problems
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with the CFI generated by GCC. */
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DWARF2_FRAME_REG_UNDEFINED,
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DWARF2_FRAME_REG_SAVED_OFFSET,
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DWARF2_FRAME_REG_SAVED_REG,
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DWARF2_FRAME_REG_SAVED_EXP,
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DWARF2_FRAME_REG_SAME_VALUE,
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/* These are defined in Dwarf3. */
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DWARF2_FRAME_REG_SAVED_VAL_OFFSET,
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DWARF2_FRAME_REG_SAVED_VAL_EXP,
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/* These aren't defined by the DWARF2 CFI specification, but are
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used internally by GDB. */
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DWARF2_FRAME_REG_FN, /* Call a registered function. */
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DWARF2_FRAME_REG_RA, /* Return Address. */
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DWARF2_FRAME_REG_RA_OFFSET, /* Return Address with offset. */
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DWARF2_FRAME_REG_CFA, /* Call Frame Address. */
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DWARF2_FRAME_REG_CFA_OFFSET /* Call Frame Address with offset. */
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};
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/* Register state. */
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struct dwarf2_frame_state_reg
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{
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/* Each register save state can be described in terms of a CFA slot,
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another register, or a location expression. */
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union {
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LONGEST offset;
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ULONGEST reg;
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const gdb_byte *exp;
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struct value *(*fn) (struct frame_info *this_frame, void **this_cache,
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int regnum);
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} loc;
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ULONGEST exp_len;
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enum dwarf2_frame_reg_rule how;
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};
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enum cfa_how_kind
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{
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CFA_UNSET,
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CFA_REG_OFFSET,
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CFA_EXP
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};
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struct dwarf2_frame_state_reg_info
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{
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struct dwarf2_frame_state_reg *reg;
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int num_regs;
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LONGEST cfa_offset;
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ULONGEST cfa_reg;
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enum cfa_how_kind cfa_how;
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const gdb_byte *cfa_exp;
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/* Used to implement DW_CFA_remember_state. */
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struct dwarf2_frame_state_reg_info *prev;
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};
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/* Structure describing a frame state. */
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struct dwarf2_frame_state
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{
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/* Each register save state can be described in terms of a CFA slot,
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another register, or a location expression. */
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struct dwarf2_frame_state_reg_info regs;
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/* The PC described by the current frame state. */
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CORE_ADDR pc;
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/* Initial register set from the CIE.
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Used to implement DW_CFA_restore. */
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struct dwarf2_frame_state_reg_info initial;
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/* The information we care about from the CIE. */
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LONGEST data_align;
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ULONGEST code_align;
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ULONGEST retaddr_column;
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/* Flags for known producer quirks. */
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/* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa
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and DW_CFA_def_cfa_offset takes a factored offset. */
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int armcc_cfa_offsets_sf;
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/* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that
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the CFA is defined as REG - OFFSET rather than REG + OFFSET. */
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int armcc_cfa_offsets_reversed;
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};
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/* Set the architecture-specific register state initialization
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function for GDBARCH to INIT_REG. */
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extern void dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
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void (*init_reg) (struct gdbarch *, int,
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struct dwarf2_frame_state_reg *,
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struct frame_info *));
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/* Set the architecture-specific signal trampoline recognition
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function for GDBARCH to SIGNAL_FRAME_P. */
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extern void
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dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
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int (*signal_frame_p) (struct gdbarch *,
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struct frame_info *));
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/* Set the architecture-specific adjustment of .eh_frame and .debug_frame
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register numbers. */
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extern void
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dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
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int (*adjust_regnum) (struct gdbarch *,
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int, int));
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/* Append the DWARF-2 frame unwinders to GDBARCH's list. */
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void dwarf2_append_unwinders (struct gdbarch *gdbarch);
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/* Return the frame base methods for the function that contains PC, or
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NULL if it can't be handled by the DWARF CFI frame unwinder. */
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extern const struct frame_base *
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dwarf2_frame_base_sniffer (struct frame_info *this_frame);
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/* Compute the DWARF CFA for a frame. */
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CORE_ADDR dwarf2_frame_cfa (struct frame_info *this_frame);
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/* Assert that the register set RS is large enough to store gdbarch_num_regs
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columns. If necessary, enlarge the register set. */
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void dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
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int num_regs);
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/* Find the CFA information for PC.
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Return 1 if a register is used for the CFA, or 0 if another
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expression is used. Throw an exception on error.
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GDBARCH is the architecture to use.
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DATA is the per-CU data.
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REGNUM_OUT is an out parameter that is set to the register number.
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OFFSET_OUT is the offset to use from this register.
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These are only filled in when 1 is returned.
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TEXT_OFFSET_OUT, CFA_START_OUT, and CFA_END_OUT describe the CFA
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in other cases. These are only used when 0 is returned. */
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extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
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struct dwarf2_per_cu_data *data,
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int *regnum_out, LONGEST *offset_out,
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CORE_ADDR *text_offset_out,
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const gdb_byte **cfa_start_out,
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const gdb_byte **cfa_end_out);
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#endif /* dwarf2-frame.h */
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