From 8ab3d180b1ce8b7cd8d63b3d34053b4bcd2dddaf Mon Sep 17 00:00:00 2001 From: Kevin Buettner Date: Tue, 12 Aug 2008 00:29:35 +0000 Subject: [PATCH] * rs6000-tdep.c (BL_MASK, BL_INSTRUCTION, BL_DISPLACEMENT_MASK): New macros. (rs6000_skip_main_prologue): New function. (rs6000_gdb_arch_init): Register rs6000_skip_main_prologue. --- gdb/ChangeLog | 7 +++++++ gdb/rs6000-tdep.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 4718d90106..d7f071ba98 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2008-08-11 Kevin Buettner + + * rs6000-tdep.c (BL_MASK, BL_INSTRUCTION, BL_DISPLACEMENT_MASK): + New macros. + (rs6000_skip_main_prologue): New function. + (rs6000_gdb_arch_init): Register rs6000_skip_main_prologue. + 2008-08-11 Sandra Loosemore * MAINTAINERS (Write After Approval): Add self. diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c index 08f926e91f..fcf43552bc 100644 --- a/gdb/rs6000-tdep.c +++ b/gdb/rs6000-tdep.c @@ -1146,6 +1146,20 @@ bl_to_blrl_insn_p (CORE_ADDR pc, int insn) return 0; } +/* Masks for decoding a branch-and-link (bl) instruction. + + BL_MASK and BL_INSTRUCTION are used in combination with each other. + The former is anded with the opcode in question; if the result of + this masking operation is equal to BL_INSTRUCTION, then the opcode in + question is a ``bl'' instruction. + + BL_DISPLACMENT_MASK is anded with the opcode in order to extract + the branch displacement. */ + +#define BL_MASK 0xfc000001 +#define BL_INSTRUCTION 0x48000001 +#define BL_DISPLACEMENT_MASK 0x03fffffc + /* return pc value after skipping a function prologue and also return information about a function frame. @@ -1769,6 +1783,41 @@ rs6000_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) return pc; } +/* When compiling for EABI, some versions of GCC emit a call to __eabi + in the prologue of main(). + + The function below examines the code pointed at by PC and checks to + see if it corresponds to a call to __eabi. If so, it returns the + address of the instruction following that call. Otherwise, it simply + returns PC. */ + +CORE_ADDR +rs6000_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) +{ + gdb_byte buf[4]; + unsigned long op; + + if (target_read_memory (pc, buf, 4)) + return pc; + op = extract_unsigned_integer (buf, 4); + + if ((op & BL_MASK) == BL_INSTRUCTION) + { + CORE_ADDR displ = op & BL_DISPLACEMENT_MASK; + CORE_ADDR call_dest = pc + 4 + displ; + struct minimal_symbol *s = lookup_minimal_symbol_by_pc (call_dest); + + /* We check for ___eabi (three leading underscores) in addition + to __eabi in case the GCC option "-fleading-underscore" was + used to compile the program. */ + if (s != NULL + && SYMBOL_LINKAGE_NAME (s) != NULL + && (strcmp (SYMBOL_LINKAGE_NAME (s), "__eabi") == 0 + || strcmp (SYMBOL_LINKAGE_NAME (s), "___eabi") == 0)) + pc += 4; + } + return pc; +} /* All the ABI's require 16 byte alignment. */ static CORE_ADDR @@ -3238,6 +3287,7 @@ rs6000_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) set_gdbarch_skip_prologue (gdbarch, rs6000_skip_prologue); set_gdbarch_in_function_epilogue_p (gdbarch, rs6000_in_function_epilogue_p); + set_gdbarch_skip_main_prologue (gdbarch, rs6000_skip_main_prologue); set_gdbarch_inner_than (gdbarch, core_addr_lessthan); set_gdbarch_breakpoint_from_pc (gdbarch, rs6000_breakpoint_from_pc);