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Move the ret_addr_column field from dwarf_reg_cache_entry to dwarf_reg_state,

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so that it will get saved and restored with the register state.  Initialize
the rs_state version of ret_addr_column at the some time the dwarf_cursor
version is initialized, and don't bother copying ret_addr_column explicitly
from cursor to cache since it's copied implicitly as part of reg_state.
Use the reg_state version in apply_reg_state, instead of the cursor version.

Which brings up the question: why do we have ret_addr_column in the dwarf_cursor?
We call find_reg_state before calling apply_reg_state, so the value of ret_addr_column
in the cursor when dwarf_step gets called gets overwritten before it is used.  So
it's initial value doesn't matter.  But some architectures do funky things with
cursor->ret_addr_column, even though I don't see how they matter.

So I'm not deleting dwarf_cursor->ret_addr_column, even though I suspect this
patch makes it useless.
This commit is contained in:
Doug Moore 2017-05-16 22:00:38 -05:00
parent 028a60f064
commit ec1a021243
2 changed files with 4 additions and 13 deletions
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2
include/dwarf.h
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@ -251,6 +251,7 @@ dwarf_where_t;
typedef struct dwarf_reg_state
{
unw_word_t ret_addr_column; /* which column in rule table represents return address */
char where[DWARF_NUM_PRESERVED_REGS + 2]; /* how is the register saved? */
unw_word_t val[DWARF_NUM_PRESERVED_REGS + 2]; /* where it's saved */
}
@ -269,7 +270,6 @@ typedef struct dwarf_reg_cache_entry
unsigned short lru_chain; /* used for least-recently-used chain */
unsigned short coll_chain; /* used for hash collisions */
unsigned short hint; /* hint for next rs to try (or -1) */
unw_word_t ret_addr_column; /* indicates which column in the rule table represents return address */
unsigned short valid : 1; /* optional machine-dependent signal info */
unsigned short signal_frame : 1; /* optional machine-dependent signal info */
}

15
src/dwarf/Gparser.c
View file

@ -488,10 +488,6 @@ static int
parse_dynamic (struct dwarf_cursor *c, unw_word_t ip, dwarf_state_record_t *sr)
{
Debug (1, "Not yet implemented\n");
#if 0
/* Don't forget to set the ret_addr_column! */
c->ret_addr_column = XXX;
#endif
return -UNW_ENOINFO;
}
@ -521,6 +517,7 @@ setup_fde (struct dwarf_cursor *c, dwarf_state_record_t *sr)
struct dwarf_cie_info *dci = c->pi.unwind_info;
c->ret_addr_column = dci->ret_addr_column;
sr->rs_current.ret_addr_column = dci->ret_addr_column;
unw_word_t addr = dci->cie_instr_start;
unw_word_t curr_ip = 0;
dwarf_stackable_reg_state_t *rs_stack = NULL;
@ -715,7 +712,6 @@ rs_new (struct dwarf_rs_cache *cache, struct dwarf_cursor * c)
cache->links[head].ip = c->ip;
cache->links[head].valid = 1;
cache->links[head].ret_addr_column = c->ret_addr_column;
cache->links[head].signal_frame = tdep_cache_frame(c);
return cache->buckets + head;
}
@ -860,11 +856,11 @@ apply_reg_state (struct dwarf_cursor *c, struct dwarf_reg_state *rs)
c->cfa = cfa;
/* DWARF spec says undefined return address location means end of stack. */
if (DWARF_IS_NULL_LOC (c->loc[c->ret_addr_column]))
if (DWARF_IS_NULL_LOC (c->loc[rs->ret_addr_column]))
c->ip = 0;
else
{
ret = dwarf_get (c, c->loc[c->ret_addr_column], &ip);
ret = dwarf_get (c, c->loc[rs->ret_addr_column], &ip);
if (ret < 0)
return ret;
c->ip = ip;
@ -898,7 +894,6 @@ find_reg_state (struct dwarf_cursor *c, dwarf_state_record_t *sr)
{
/* update hint; no locking needed: single-word writes are atomic */
unsigned short index = rs - cache->buckets;
c->ret_addr_column = cache->links[index].ret_addr_column;
c->use_prev_instr = ! cache->links[index].signal_frame;
memcpy (&sr->rs_current, rs, sizeof (*rs));
}
@ -982,10 +977,6 @@ dwarf_reg_states_dynamic_iterate(struct dwarf_cursor *c,
void *token)
{
Debug (1, "Not yet implemented\n");
#if 0
/* Don't forget to set the ret_addr_column! */
c->ret_addr_column = XXX;
#endif
return -UNW_ENOINFO;
}