diff options
Diffstat (limited to 'gdb/s390-tdep.c')
| -rw-r--r-- | gdb/s390-tdep.c | 37 |
1 files changed, 33 insertions, 4 deletions
diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c index d29327a..4e8c57c 100644 --- a/gdb/s390-tdep.c +++ b/gdb/s390-tdep.c @@ -209,13 +209,28 @@ s390_get_frame_info (CORE_ADDR pc, struct frame_extra_info *fextra_info, int fprs_saved[S390_NUM_FPRS]; int regidx, instrlen; int save_link_regidx, subtract_sp_regidx; - int const_pool_state, save_link_state, got_state; + int const_pool_state, save_link_state; int frame_pointer_found, varargs_state; int loop_cnt, gdb_gpr_store, gdb_fpr_store; int frame_pointer_regidx = 0xf; int offset, expected_offset; int err = 0; disassemble_info info; + + /* What we've seen so far regarding r12 --- the GOT (Global Offset + Table) pointer. We expect to see `l %r12, N(%r13)', which loads + r12 with the offset from the constant pool to the GOT, and then + an `ar %r12, %r13', which adds the constant pool address, + yielding the GOT's address. Here's what got_state means: + 0 -- seen nothing + 1 -- seen `l %r12, N(%r13)', but no `ar' + 2 -- seen load and add, so GOT pointer is totally initialized + When got_state is 1, then got_load_addr is the address of the + load instruction, and got_load_len is the length of that + instruction. */ + int got_state; + CORE_ADDR got_load_addr, got_load_len; + const_pool_state = save_link_state = got_state = varargs_state = 0; frame_pointer_found = 0; memset (gprs_saved, 0, sizeof (gprs_saved)); @@ -539,7 +554,9 @@ s390_get_frame_info (CORE_ADDR pc, struct frame_extra_info *fextra_info, && (instr[2] == (CONST_POOL_REGIDX << 4)) && ((instr[1] >> 4) == GOT_REGIDX)) { - got_state == 1; + got_state = 1; + got_load_addr = test_pc; + got_load_len = instrlen; valid_prologue = 1; continue; } @@ -556,8 +573,20 @@ s390_get_frame_info (CORE_ADDR pc, struct frame_extra_info *fextra_info, while (valid_prologue && good_prologue); if (good_prologue) { - good_prologue = (((got_state == 0) || (got_state == 2)) && - ((const_pool_state == 0) || (const_pool_state == 2)) && + /* If this function doesn't reference the global offset table, + then the compiler may use r12 for other things. If the last + instruction we saw was a load of r12 from the constant pool, + with no subsequent add to make the address PC-relative, then + the load was probably a genuine body instruction; don't treat + it as part of the prologue. */ + if (got_state == 1 + && got_load_addr + got_load_len == test_pc) + { + test_pc = got_load_addr; + instrlen = got_load_len; + } + + good_prologue = (((const_pool_state == 0) || (const_pool_state == 2)) && ((save_link_state == 0) || (save_link_state == 4)) && ((varargs_state == 0) || (varargs_state == 2))); } |