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Re: [RFA] sighandler backtrace on x86-64


Michal Ludvig writes:
 > Hi all,
 > the attached patch enables backtrace through signal handlers on x86-64. 
 > It isn't yet complete, but this is the part that works.
 > Can someone approve it please?
 > 
 > Michal Ludvig
 > -- 
 > * SuSE CR, s.r.o     * mludvig@suse.cz
 > * +420 2 9654 5373   * http://www.suse.cz
 > 2002-09-18  Michal Ludvig  <mludvig@suse.cz>
 > 
 > 	* dwarf2cfi.c (struct context)
 > 	(struct context_reg): Moved to dwarf2cfi.h
 > 	(context_alloc, frame_state_alloc, context_cpy):
 > 	Made extern instead of static, removed prototypes.
 > 	* dwarf2cfi.h (struct context)
 > 	(struct context_reg): New, moved from dwarf2cfi.c
 > 	(context_alloc, frame_state_alloc, context_cpy):
 > 	New prototypes.


I don't see any uses of the structures and functions you are exporting.
Could you postpone these changes until they are actually used?
I have some comments anyway, see below.

 > 	* x86-64-linux-tdep.c (x86_64_linux_sigtramp_saved_pc):
 > 	Changed from static to extern.
 > 	(LINUX_SIGINFO_SIZE, LINUX_SIGCONTEXT_PC_OFFSET)
 > 	(LINUX_SIGCONTEXT_FP_OFFSET)
 > 	(LINUX_UCONTEXT_SIGCONTEXT_OFFSET): Adjusted.
 > 	(x86_64_linux_in_sigtramp, x86_64_linux_frame_chain)
 > 	(x86_64_init_frame_pc, x86_64_init_extra_frame_info): New.
 > 	* x86-64-tdep.c (x86_64_gdbarch_init): Several
 > 	set_gdbarch_*() calls now use x86-64 specific functions 
 > 	instead of DWARF2 CFI ones.
 > 	* x86-64-tdep.h (x86_64_linux_in_sigtramp)
 > 	(x86_64_linux_frame_chain, x86_64_init_frame_pc)
 > 	(x86_64_init_extra_frame_info): New prototypes.
 > 	
 > Index: dwarf2cfi.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/dwarf2cfi.c,v
 > retrieving revision 1.16
 > diff -u -p -r1.16 dwarf2cfi.c
 > --- dwarf2cfi.c	19 Jul 2002 09:40:51 -0000	1.16
 > +++ dwarf2cfi.c	18 Sep 2002 11:11:02 -0000
 > @@ -90,37 +90,6 @@ struct fde_array
 >    int array_size;
 >  };
 >  
 > -struct context_reg
 > -{
 > -  union
 > -  {
 > -    unsigned int reg;
 > -    long offset;
 > -    CORE_ADDR addr;
 > -  }
 > -  loc;
 > -  enum
 > -  {
 > -    REG_CTX_UNSAVED,
 > -    REG_CTX_SAVED_OFFSET,
 > -    REG_CTX_SAVED_REG,
 > -    REG_CTX_SAVED_ADDR,
 > -    REG_CTX_VALUE,
 > -  }
 > -  how;
 > -};
 > -
 > -/* This is the register and unwind state for a particular frame.  */
 > -struct context
 > -{
 > -  struct context_reg *reg;
 > -
 > -  CORE_ADDR cfa;
 > -  CORE_ADDR ra;
 > -  void *lsda;
 > -  int args_size;
 > -};
 > -
 >  struct frame_state_reg
 >  {
 >    union
 > @@ -208,11 +177,8 @@ static struct fde_unit *fde_unit_alloc (
 >  static struct cie_unit *cie_unit_alloc (void);
 >  static void fde_chunks_need_space ();
 >  
 > -static struct context *context_alloc ();
 > -static struct frame_state *frame_state_alloc ();
 >  static void unwind_tmp_obstack_init ();
 >  static void unwind_tmp_obstack_free ();
 > -static void context_cpy (struct context *dst, struct context *src);
 >  
 >  static unsigned int read_1u (bfd * abfd, char **p);
 >  static int read_1s (bfd * abfd, char **p);
 > @@ -286,7 +252,7 @@ fde_chunks_need_space (void)
 >  }
 >  
 >  /* Alocate a new `struct context' on temporary obstack.  */
 > -static struct context *
 > +struct context *
 >  context_alloc (void)
 >  {
 >    struct context *context;
 > @@ -303,7 +269,7 @@ context_alloc (void)
 >  }
 >  
 >  /* Alocate a new `struct frame_state' on temporary obstack.  */
 > -static struct frame_state *
 > +struct frame_state *
 >  frame_state_alloc (void)
 >  {
 >    struct frame_state *fs;
 > @@ -332,7 +298,7 @@ unwind_tmp_obstack_free (void)
 >    unwind_tmp_obstack_init ();
 >  }
 >  
 > -static void
 > +void
 >  context_cpy (struct context *dst, struct context *src)
 >  {
 >    int regs_size = sizeof (struct context_reg) * NUM_REGS;
 > Index: dwarf2cfi.h
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/dwarf2cfi.h,v
 > retrieving revision 1.1
 > diff -u -p -r1.1 dwarf2cfi.h
 > --- dwarf2cfi.h	7 Dec 2001 12:10:15 -0000	1.1
 > +++ dwarf2cfi.h	18 Sep 2002 11:11:02 -0000
 > @@ -22,6 +22,37 @@
 >  #ifndef DWARF2CFI_H
 >  #define DWARF2CFI_H
 >  
 > +struct context_reg
 > +{
 > +  union
 > +  {
 > +    unsigned int reg;
 > +    long offset;
 > +    CORE_ADDR addr;
 > +  }
 > +  loc;
 > +  enum
 > +  {
 > +    REG_CTX_UNSAVED,
 > +    REG_CTX_SAVED_OFFSET,
 > +    REG_CTX_SAVED_REG,
 > +    REG_CTX_SAVED_ADDR,
 > +    REG_CTX_VALUE,
 > +  }
 > +  how;
 > +};
 > +
 > +/* This is the register and unwind state for a particular frame.  */
 > +struct context
 > +{
 > +  struct context_reg *reg;
 > +
 > +  CORE_ADDR cfa;
 > +  CORE_ADDR ra;
 > +  void *lsda;
 > +  int args_size;
 > +};
 > +


Do you need to make the whole structure accessible? would it be enough
for your purposes to just add
struct context;
struct context_reg;

to the .h file?


 >  /* Return the frame address.  */
 >  CORE_ADDR cfi_read_fp ();
 >  
 > @@ -63,4 +94,7 @@ void cfi_get_saved_register (char *raw_b
 >  void cfi_virtual_frame_pointer (CORE_ADDR pc, int *frame_regnum,
 >  				LONGEST * frame_offset);
 >  
 > +struct context *context_alloc ();
 > +void context_cpy (struct context *dst, struct context *src);
 > +struct frame_state *frame_state_alloc ();

'extern' keyword?

Elena


 >  #endif
 > Index: x86-64-linux-tdep.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/x86-64-linux-tdep.c,v
 > retrieving revision 1.5
 > diff -u -p -r1.5 x86-64-linux-tdep.c
 > --- x86-64-linux-tdep.c	3 Sep 2002 13:06:33 -0000	1.5
 > +++ x86-64-linux-tdep.c	18 Sep 2002 11:11:02 -0000
 > @@ -35,8 +35,10 @@
 >  #define LINUX_SIGTRAMP_OFFSET1 (7)
 >  
 >  static const unsigned char linux_sigtramp_code[] = {
 > -  LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x89, 0x00, 0x00, 0x00,	/*  mov $0x89,%rax */
 > -  LINUX_SIGTRAMP_INSN1, 0x05	/* syscall */
 > +  /*  mov $__NR_rt_sigreturn,%rax */	
 > +  LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,
 > +  /* syscall */
 > +  LINUX_SIGTRAMP_INSN1, 0x05
 >  };
 >  
 >  #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
 > @@ -68,17 +70,22 @@ x86_64_linux_sigtramp_start (CORE_ADDR p
 >    return pc;
 >  }
 >  
 > -#define LINUX_SIGINFO_SIZE 128
 > +#define LINUX_SIGINFO_SIZE 0
 >  
 >  /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */
 > -#define LINUX_UCONTEXT_SIGCONTEXT_OFFSET (36)
 > +#define LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40
 > +
 > +/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
 > +#define LINUX_SIGCONTEXT_PC_OFFSET 128
 > +#define LINUX_SIGCONTEXT_FP_OFFSET 120
 >  
 >  /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
 >     address of the associated sigcontext structure.  */
 > -CORE_ADDR
 > +static CORE_ADDR
 >  x86_64_linux_sigcontext_addr (struct frame_info *frame)
 >  {
 >    CORE_ADDR pc;
 > +  ULONGEST rsp;
 >  
 >    pc = x86_64_linux_sigtramp_start (frame->pc);
 >    if (pc)
 > @@ -92,7 +99,8 @@ x86_64_linux_sigcontext_addr (struct fra
 >  
 >  
 >        /* This is the top frame. */
 > -      return read_register (SP_REGNUM) + LINUX_SIGINFO_SIZE +
 > +      rsp = read_register (SP_REGNUM);
 > +      return rsp + LINUX_SIGINFO_SIZE +
 >  	LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 >  
 >      }
 > @@ -101,13 +109,10 @@ x86_64_linux_sigcontext_addr (struct fra
 >    return 0;
 >  }
 >  
 > -/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
 > -#define LINUX_SIGCONTEXT_PC_OFFSET (136)
 > -
 >  /* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
 >     saved program counter.  */
 >  
 > -CORE_ADDR
 > +static CORE_ADDR
 >  x86_64_linux_sigtramp_saved_pc (struct frame_info *frame)
 >  {
 >    CORE_ADDR addr;
 > @@ -134,4 +139,62 @@ x86_64_linux_frame_saved_pc (struct fram
 >    if (frame->signal_handler_caller)
 >      return x86_64_linux_sigtramp_saved_pc (frame);
 >    return cfi_get_ra (frame);
 > +}
 > +
 > +/* Return whether PC is in a GNU/Linux sigtramp routine.  */
 > +
 > +int
 > +x86_64_linux_in_sigtramp (CORE_ADDR pc, char *name)
 > +{
 > +  if (name)
 > +    return STREQ ("__restore_rt", name);
 > +  
 > +  return (x86_64_linux_sigtramp_start (pc) != 0);
 > +}
 > +
 > +CORE_ADDR
 > +x86_64_linux_frame_chain (struct frame_info *fi)
 > +{
 > +	ULONGEST addr;
 > +	CORE_ADDR fp, pc;
 > +	
 > +	if (! fi->signal_handler_caller)
 > +	{
 > +		fp = cfi_frame_chain (fi);
 > +		if(fp)
 > +			return fp;
 > +		else
 > +			addr = fi->frame;
 > +	}
 > +	else
 > +		addr = fi->next->frame;
 > +
 > +	addr += LINUX_SIGINFO_SIZE + LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 > +	
 > +	fp = read_memory_integer (addr + LINUX_SIGCONTEXT_FP_OFFSET, 8)+8;
 > +	
 > +	return fp;
 > +}
 > +
 > +void
 > +x86_64_init_frame_pc (int fromleaf, struct frame_info *fi)
 > +{
 > +	CORE_ADDR addr;
 > +
 > +	if(fi->next && fi->next->signal_handler_caller)
 > +	{
 > +		addr = fi->next->next->frame 
 > +			+ LINUX_SIGINFO_SIZE 
 > +			+ LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
 > +		fi->pc = read_memory_integer (addr 
 > +				+ LINUX_SIGCONTEXT_PC_OFFSET, 8);
 > +	}
 > +	else
 > +		cfi_init_frame_pc (fromleaf, fi);
 > +}
 > +
 > +void
 > +x86_64_init_extra_frame_info (int fromleaf, struct frame_info *fi)
 > +{
 > +	cfi_init_extra_frame_info (fromleaf, fi);
 >  }
 > Index: x86-64-tdep.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/x86-64-tdep.c,v
 > retrieving revision 1.27
 > diff -u -p -r1.27 x86-64-tdep.c
 > --- x86-64-tdep.c	12 Sep 2002 08:39:26 -0000	1.27
 > +++ x86-64-tdep.c	18 Sep 2002 11:11:03 -0000
 > @@ -1026,7 +1026,7 @@ x86_64_gdbarch_init (struct gdbarch_info
 >  
 >    /* FRAME_CHAIN takes a frame's nominal address and produces the frame's
 >       chain-pointer.  */
 > -  set_gdbarch_frame_chain (gdbarch, cfi_frame_chain);
 > +  set_gdbarch_frame_chain (gdbarch, x86_64_linux_frame_chain);
 >  
 >    set_gdbarch_frameless_function_invocation (gdbarch,
 >  					     x86_64_frameless_function_invocation);
 > @@ -1041,10 +1041,10 @@ x86_64_gdbarch_init (struct gdbarch_info
 >    set_gdbarch_frame_init_saved_regs (gdbarch, x86_64_frame_init_saved_regs);
 >  
 >  /* Frame pc initialization is handled by unwind informations.  */
 > -  set_gdbarch_init_frame_pc (gdbarch, cfi_init_frame_pc);
 > +  set_gdbarch_init_frame_pc (gdbarch, x86_64_init_frame_pc);
 >  
 >  /* Initialization of unwind informations.  */
 > -  set_gdbarch_init_extra_frame_info (gdbarch, cfi_init_extra_frame_info);
 > +  set_gdbarch_init_extra_frame_info (gdbarch, x86_64_init_extra_frame_info);
 >  
 >  /* Getting saved registers is handled by unwind informations.  */
 >    set_gdbarch_get_saved_register (gdbarch, cfi_get_saved_register);
 > @@ -1054,8 +1054,7 @@ x86_64_gdbarch_init (struct gdbarch_info
 >  /* Cons up virtual frame pointer for trace */
 >    set_gdbarch_virtual_frame_pointer (gdbarch, cfi_virtual_frame_pointer);
 >  
 > -
 > -  set_gdbarch_frame_chain_valid (gdbarch, generic_file_frame_chain_valid);
 > +  set_gdbarch_frame_chain_valid (gdbarch, file_frame_chain_valid);
 >  
 >    set_gdbarch_use_generic_dummy_frames (gdbarch, 1);
 >    set_gdbarch_call_dummy_location (gdbarch, AT_ENTRY_POINT);
 > @@ -1121,6 +1120,8 @@ x86_64_gdbarch_init (struct gdbarch_info
 >  /* Use dwarf2 debug frame informations.  */
 >    set_gdbarch_dwarf2_build_frame_info (gdbarch, dwarf2_build_frame_info);
 >    set_gdbarch_dwarf2_reg_to_regnum (gdbarch, x86_64_dwarf2_reg_to_regnum);
 > +
 > +  set_gdbarch_pc_in_sigtramp (gdbarch, x86_64_linux_in_sigtramp);
 >  
 >    return gdbarch;
 >  }
 > Index: x86-64-tdep.h
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/x86-64-tdep.h,v
 > retrieving revision 1.5
 > diff -u -p -r1.5 x86-64-tdep.h
 > --- x86-64-tdep.h	20 Jun 2002 13:08:12 -0000	1.5
 > +++ x86-64-tdep.h	18 Sep 2002 11:11:03 -0000
 > @@ -31,8 +31,12 @@ extern int x86_64_num_gregs;
 >  int x86_64_register_number (const char *name);
 >  const char *x86_64_register_name (int reg_nr);
 >  	
 > -
 >  gdbarch_frame_saved_pc_ftype x86_64_linux_frame_saved_pc;
 >  gdbarch_saved_pc_after_call_ftype x86_64_linux_saved_pc_after_call;
 > +gdbarch_pc_in_sigtramp_ftype x86_64_linux_in_sigtramp;
 > +CORE_ADDR x86_64_linux_frame_chain (struct frame_info *fi);
 > +void x86_64_init_frame_pc (int fromleaf, struct frame_info *fi);
 > +void x86_64_init_extra_frame_info (int fromleaf, struct frame_info *fi);
 > +
 >  
 >  #endif


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