From 46ad3598b7b18c814e7ff899a3cfb1314fb59e77 Mon Sep 17 00:00:00 2001 From: Ulrich Weigand Date: Fri, 25 Nov 2011 17:05:42 +0000 Subject: [PATCH] =?utf8?q?2011-11-25=20=C2=A0Uros=20Bizjak=20=C2=A0?= MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit * alpha-tdep.c (br_opcode): New. (ldl_l_opcode, ldq_l_opcode, stl_c_opcode, stq_c_opcode): Ditto. (alpha_deal_with_atomic_sequence): New function. (alpha_gdbarch_init): Handle single stepping of atomic sequences with alpha_deal_with_atomic_sequence. --- gdb/ChangeLog | 8 +++++ gdb/alpha-tdep.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 100 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index a363cc5..c765e01 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2011-11-25  Uros Bizjak   + + * alpha-tdep.c (br_opcode): New. + (ldl_l_opcode, ldq_l_opcode, stl_c_opcode, stq_c_opcode): Ditto. + (alpha_deal_with_atomic_sequence): New function. + (alpha_gdbarch_init): Handle single stepping of atomic sequences + with alpha_deal_with_atomic_sequence. + 2011-11-24 Tristan Gingold * machoread.c (oso_el): Remove num_Sections, symbols, offsets diff --git a/gdb/alpha-tdep.c b/gdb/alpha-tdep.c index 77782e8..3c2a6ae 100644 --- a/gdb/alpha-tdep.c +++ b/gdb/alpha-tdep.c @@ -65,6 +65,7 @@ static const int stq_opcode = 0x2d; /* Branch instruction format */ #define BR_RA(insn) MEM_RA(insn) +static const int br_opcode = 0x30; static const int bne_opcode = 0x3d; /* Operate instruction format */ @@ -762,6 +763,94 @@ alpha_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) } +static const int ldl_l_opcode = 0x2a; +static const int ldq_l_opcode = 0x2b; +static const int stl_c_opcode = 0x2e; +static const int stq_c_opcode = 0x2f; + +/* Checks for an atomic sequence of instructions beginning with a LDL_L/LDQ_L + instruction and ending with a STL_C/STQ_C instruction. If such a sequence + is found, attempt to step through it. A breakpoint is placed at the end of + the sequence. */ + +int +alpha_deal_with_atomic_sequence (struct frame_info *frame) +{ + struct gdbarch *gdbarch = get_frame_arch (frame); + struct address_space *aspace = get_frame_address_space (frame); + CORE_ADDR pc = get_frame_pc (frame); + CORE_ADDR breaks[2] = {-1, -1}; + CORE_ADDR loc = pc; + CORE_ADDR closing_insn; /* Instruction that closes the atomic sequence. */ + unsigned int insn = alpha_read_insn (gdbarch, loc); + int insn_count; + int index; + int last_breakpoint = 0; /* Defaults to 0 (no breakpoints placed). */ + const int atomic_sequence_length = 16; /* Instruction sequence length. */ + int bc_insn_count = 0; /* Conditional branch instruction count. */ + + /* Assume all atomic sequences start with a LDL_L/LDQ_L instruction. */ + if (INSN_OPCODE (insn) != ldl_l_opcode + && INSN_OPCODE (insn) != ldq_l_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) + { + loc += ALPHA_INSN_SIZE; + insn = alpha_read_insn (gdbarch, 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. */ + if (INSN_OPCODE (insn) >= br_opcode) + { + int immediate = (insn & 0x001fffff) << 2; + + immediate = (immediate ^ 0x400000) - 0x400000; + + if (bc_insn_count >= 1) + return 0; /* More than one branch found, fallback + to the standard single-step code. */ + + breaks[1] = loc + ALPHA_INSN_SIZE + immediate; + + bc_insn_count++; + last_breakpoint++; + } + + if (INSN_OPCODE (insn) == stl_c_opcode + || INSN_OPCODE (insn) == stq_c_opcode) + break; + } + + /* Assume that the atomic sequence ends with a STL_C/STQ_C instruction. */ + if (INSN_OPCODE (insn) != stl_c_opcode + && INSN_OPCODE (insn) != stq_c_opcode) + return 0; + + closing_insn = loc; + loc += ALPHA_INSN_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) anywhere in sequence. */ + if (last_breakpoint + && (breaks[1] == breaks[0] + || (breaks[1] >= pc && breaks[1] <= closing_insn))) + last_breakpoint = 0; + + /* Effectively inserts the breakpoints. */ + for (index = 0; index <= last_breakpoint; index++) + insert_single_step_breakpoint (gdbarch, aspace, breaks[index]); + + return 1; +} + + /* Figure out where the longjmp will land. We expect the first arg to be a pointer to the jmp_buf structure from which we extract the PC (JB_PC) that we will land at. The PC is copied @@ -1749,6 +1838,9 @@ alpha_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) set_gdbarch_decr_pc_after_break (gdbarch, ALPHA_INSN_SIZE); set_gdbarch_cannot_step_breakpoint (gdbarch, 1); + /* Handles single stepping of atomic sequences. */ + set_gdbarch_software_single_step (gdbarch, alpha_deal_with_atomic_sequence); + /* Hook in ABI-specific overrides, if they have been registered. */ gdbarch_init_osabi (info, gdbarch); -- 2.7.4