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2007-10-23 Atsushi Nemoto <anemo@mba.ocn.ne.jp>

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* mips-tdep.c (LL_OPCODE, LLD_OPCODE, SC_OPCODE, SCD_OPCODE): Define.
	(deal_with_atomic_sequence): New.
	(mips_software_single_step): Use it.
This commit is contained in:
Daniel Jacobowitz 2007-10-23 13:11:47 +00:00
parent f94498ff0f
commit 3d5f6d122e
2 changed files with 114 additions and 0 deletions
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6
gdb/ChangeLog
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@ -1,3 +1,9 @@
2007-10-23 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
* mips-tdep.c (LL_OPCODE, LLD_OPCODE, SC_OPCODE, SCD_OPCODE): Define.
(deal_with_atomic_sequence): New.
(mips_software_single_step): Use it.
2007-10-23 Daniel Jacobowitz <dan@codesourcery.com>
PR gdb/2336

108
gdb/mips-tdep.c
View file

@ -2297,6 +2297,111 @@ mips_addr_bits_remove (CORE_ADDR addr)
return addr;
}
/* Instructions used during single-stepping of atomic sequences. */
#define LL_OPCODE 0x30
#define LLD_OPCODE 0x34
#define SC_OPCODE 0x38
#define SCD_OPCODE 0x3c
/* Checks for an atomic sequence of instructions beginning with a LL/LLD
instruction and ending with a SC/SCD instruction. If such a sequence
is found, attempt to step through it. A breakpoint is placed at the end of
the sequence. */
static int
deal_with_atomic_sequence (CORE_ADDR pc)
{
CORE_ADDR breaks[2] = {-1, -1};
CORE_ADDR loc = pc;
CORE_ADDR branch_bp; /* Breakpoint at branch instruction's destination. */
unsigned long insn;
int insn_count;
int index;
int last_breakpoint = 0; /* Defaults to 0 (no breakpoints placed). */
const int atomic_sequence_length = 16; /* Instruction sequence length. */
if (pc & 0x01)
return 0;
insn = mips_fetch_instruction (loc);
/* Assume all atomic sequences start with a ll/lld instruction. */
if (itype_op (insn) != LL_OPCODE && itype_op (insn) != LLD_OPCODE)
return 0;
/* Assume that no atomic sequence is longer than "atomic_sequence_length"
instructions. */
for (insn_count = 0; insn_count < atomic_sequence_length; ++insn_count)
{
int is_branch = 0;
loc += MIPS_INSN32_SIZE;
insn = mips_fetch_instruction (loc);
/* Assume that there is at most one branch in the atomic
sequence. If a branch is found, put a breakpoint in its
destination address. */
switch (itype_op (insn))
{
case 0: /* SPECIAL */
if (rtype_funct (insn) >> 1 == 4) /* JR, JALR */
return 0; /* fallback to the standard single-step code. */
break;
case 1: /* REGIMM */
is_branch = ((itype_rt (insn) & 0xc0) == 0); /* B{LT,GE}Z* */
break;
case 2: /* J */
case 3: /* JAL */
return 0; /* fallback to the standard single-step code. */
case 4: /* BEQ */
case 5: /* BNE */
case 6: /* BLEZ */
case 7: /* BGTZ */
case 20: /* BEQL */
case 21: /* BNEL */
case 22: /* BLEZL */
case 23: /* BGTTL */
is_branch = 1;
break;
case 17: /* COP1 */
case 18: /* COP2 */
case 19: /* COP3 */
is_branch = (itype_rs (insn) == 8); /* BCzF, BCzFL, BCzT, BCzTL */
break;
}
if (is_branch)
{
branch_bp = loc + mips32_relative_offset (insn) + 4;
if (last_breakpoint >= 1)
return 0; /* More than one branch found, fallback to the
standard single-step code. */
breaks[1] = branch_bp;
last_breakpoint++;
}
if (itype_op (insn) == SC_OPCODE || itype_op (insn) == SCD_OPCODE)
break;
}
/* Assume that the atomic sequence ends with a sc/scd instruction. */
if (itype_op (insn) != SC_OPCODE && itype_op (insn) != SCD_OPCODE)
return 0;
loc += MIPS_INSN32_SIZE;
/* Insert a breakpoint right after the end of the atomic sequence. */
breaks[0] = loc;
/* Check for duplicated breakpoints. Check also for a breakpoint
placed (branch instruction's destination) in the atomic sequence */
if (last_breakpoint && pc <= breaks[1] && breaks[1] <= breaks[0])
last_breakpoint = 0;
/* Effectively inserts the breakpoints. */
for (index = 0; index <= last_breakpoint; index++)
insert_single_step_breakpoint (breaks[index]);
return 1;
}
/* mips_software_single_step() is called just before we want to resume
the inferior, if we want to single-step it but there is no hardware
or kernel single-step support (MIPS on GNU/Linux for example). We find
@ -2308,6 +2413,9 @@ mips_software_single_step (struct frame_info *frame)
CORE_ADDR pc, next_pc;
pc = get_frame_pc (frame);
if (deal_with_atomic_sequence (pc))
return 1;
next_pc = mips_next_pc (frame, pc);
insert_single_step_breakpoint (next_pc);