diff options
Diffstat (limited to 'gdb/alpha-linux-tdep.c')
| -rw-r--r-- | gdb/alpha-linux-tdep.c | 134 |
1 files changed, 81 insertions, 53 deletions
diff --git a/gdb/alpha-linux-tdep.c b/gdb/alpha-linux-tdep.c index c5d7481fbf9..e89a0fa5fe1 100644 --- a/gdb/alpha-linux-tdep.c +++ b/gdb/alpha-linux-tdep.c @@ -23,93 +23,121 @@ #include "gdbcore.h" #include "value.h" #include "osabi.h" +#include "gdb_assert.h" #include "alpha-tdep.h" -/* Under GNU/Linux, signal handler invocations can be identified by the - designated code sequence that is used to return from a signal +/* Under GNU/Linux, signal handler invocations can be identified by + the designated code sequence that is used to return from a signal handler. In particular, the return address of a signal handler - points to the following sequence (the first instruction is quadword - aligned): - - bis $30,$30,$16 - addq $31,0x67,$0 - call_pal callsys - - Each instruction has a unique encoding, so we simply attempt to - match the instruction the pc is pointing to with any of the above - instructions. If there is a hit, we know the offset to the start - of the designated sequence and can then check whether we really are - executing in a designated sequence. If not, -1 is returned, - otherwise the offset from the start of the desingated sequence is - returned. - - There is a slight chance of false hits: code could jump into the - middle of the designated sequence, in which case there is no - guarantee that we are in the middle of a sigreturn syscall. Don't - think this will be a problem in praxis, though. */ -LONGEST -alpha_linux_sigtramp_offset (CORE_ADDR pc) + points to a sequence that copies $sp to $16, loads $0 with the + appropriate syscall number, and finally enters the kernel. + + This is somewhat complicated in that: + (1) the expansion of the "mov" assembler macro has changed over + time, from "bis src,src,dst" to "bis zero,src,dst", + (2) the kernel has changed from using "addq" to "lda" to load the + syscall number, + (3) there is a "normal" sigreturn and an "rt" sigreturn which + has a different stack layout. +*/ + +static long +alpha_linux_sigtramp_offset_1 (CORE_ADDR pc) { - unsigned int i[3], w; - long off; + switch (alpha_read_insn (pc)) + { + case 0x47de0410: /* bis $30,$30,$16 */ + case 0x47fe0410: /* bis $31,$30,$16 */ + return 0; - if (read_memory_nobpt (pc, (char *) &w, 4) != 0) - return -1; + case 0x43ecf400: /* addq $31,103,$0 */ + case 0x201f0067: /* lda $0,103($31) */ + case 0x201f015f: /* lda $0,351($31) */ + return 4; + + case 0x00000083: /* call_pal callsys */ + return 8; - off = -1; - switch (w) - { - case 0x47de0410: - off = 0; - break; /* bis $30,$30,$16 */ - case 0x43ecf400: - off = 4; - break; /* addq $31,0x67,$0 */ - case 0x00000083: - off = 8; - break; /* call_pal callsys */ default: return -1; } +} + +static LONGEST +alpha_linux_sigtramp_offset (CORE_ADDR pc) +{ + long i, off; + + if (pc & 3) + return -1; + + /* Guess where we might be in the sequence. */ + off = alpha_linux_sigtramp_offset_1 (pc); + if (off < 0) + return -1; + + /* Verify that the other two insns of the sequence are as we expect. */ pc -= off; - if (pc & 0x7) + for (i = 0; i < 12; i += 4) { - /* designated sequence is not quadword aligned */ - return -1; + if (i == off) + continue; + if (alpha_linux_sigtramp_offset_1 (pc + i) != i) + return -1; } - if (read_memory_nobpt (pc, (char *) i, sizeof (i)) != 0) - return -1; - - if (i[0] == 0x47de0410 && i[1] == 0x43ecf400 && i[2] == 0x00000083) - return off; - return -1; + return off; } static int alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name) { - return (alpha_linux_sigtramp_offset (pc) >= 0); + return alpha_linux_sigtramp_offset (pc) >= 0; } static CORE_ADDR -alpha_linux_sigcontext_addr (struct frame_info *frame) +alpha_linux_sigcontext_addr (struct frame_info *next_frame) { - return (get_frame_base (frame) - 0x298); /* sizeof(struct sigcontext) */ + CORE_ADDR pc; + ULONGEST sp; + long off; + + pc = frame_pc_unwind (next_frame); + frame_unwind_unsigned_register (next_frame, ALPHA_SP_REGNUM, &sp); + + off = alpha_linux_sigtramp_offset (pc); + gdb_assert (off >= 0); + + /* __NR_rt_sigreturn has a couple of structures on the stack. This is: + + struct rt_sigframe { + struct siginfo info; + struct ucontext uc; + }; + + offsetof (struct rt_sigframe, uc.uc_mcontext); + */ + if (alpha_read_insn (pc - off + 4) == 0x201f015f) + return sp + 176; + + /* __NR_sigreturn has the sigcontext structure at the top of the stack. */ + return sp; } static void alpha_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) { - struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + struct gdbarch_tdep *tdep; + + alpha_mdebug_init_abi (info, gdbarch); set_gdbarch_pc_in_sigtramp (gdbarch, alpha_linux_pc_in_sigtramp); + tdep = gdbarch_tdep (gdbarch); tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset; tdep->sigcontext_addr = alpha_linux_sigcontext_addr; - tdep->jb_pc = 2; tdep->jb_elt_size = 8; } |