[PATCH 25/26] gdbserver: refuse null argument in regcache::supply_regblock

Tankut Baris Aktemur via Gdb-patches
2023-02-28T11:32:21Z

The regcache::supply_regblock method implements two different
behaviors based on whether its 'buf' argument is null. The null
behavior is used only in tracepoint.cc. Refuse the null pointer
argument and use the 'discard' method to obtain that second behavior.

Note that the original code resets register statuses to
REG_UNAVAILABLE, but 'discard' sets them to REG_UNKNOWN. For the
current purposes of resetting the regcache, the difference does not
seem to be important.
---
gdbserver/regcache.cc | 19 +++++--------------
gdbserver/regcache.h | 3 +--
gdbserver/tracepoint.cc | 8 ++++----
3 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/gdbserver/regcache.cc b/gdbserver/regcache.cc
index 4533e9e9b12..cfb68774402 100644
--- a/gdbserver/regcache.cc
+++ b/gdbserver/regcache.cc
@@ -390,22 +390,13 @@ supply_register_by_name_zeroed (struct regcache *regcache,
void
regcache::supply_regblock (const void *buf)
{
- if (buf != nullptr)
- {
- memcpy (registers, buf, tdesc->registers_size);
-#ifndef IN_PROCESS_AGENT
- for (int i = 0; i < tdesc->reg_defs.size (); i++)
- set_register_status (i, REG_VALID);
-#endif
- }
- else
- {
- memset (registers, 0, tdesc->registers_size);
+ gdb_assert (buf != nullptr);
+
+ memcpy (registers, buf, tdesc->registers_size);
#ifndef IN_PROCESS_AGENT
- for (int i = 0; i < tdesc->reg_defs.size (); i++)
- set_register_status (i, REG_UNAVAILABLE);
+ for (int i = 0; i < tdesc->reg_defs.size (); i++)
+ set_register_status (i, REG_VALID);
#endif
- }
}

#ifndef IN_PROCESS_AGENT
diff --git a/gdbserver/regcache.h b/gdbserver/regcache.h
index be412bc3765..216044889ec 100644
--- a/gdbserver/regcache.h
+++ b/gdbserver/regcache.h
@@ -103,8 +103,7 @@ struct regcache : public reg_buffer_common
void registers_from_string (const char *buf);

/* Supply the whole register set whose contents are stored in BUF,
- to this regcache. If BUF is NULL, all the registers' values are
- recorded as unavailable. */
+ to this regcache. BUF cannot be NULL. */
void supply_regblock (const void *buf);

/* Return the pointer to the register with number REGNUM. */
diff --git a/gdbserver/tracepoint.cc b/gdbserver/tracepoint.cc
index 9833e7c3b0f..9622d53cd82 100644
--- a/gdbserver/tracepoint.cc
+++ b/gdbserver/tracepoint.cc
@@ -4707,7 +4707,7 @@ get_context_regcache (struct tracepoint_hit_ctx *ctx)
{
fctx->regcache_initted = 1;
fctx->regcache.initialize (ipa_tdesc, fctx->regspace);
- fctx->regcache.supply_regblock (nullptr);
+ fctx->regcache.discard ();
supply_fast_tracepoint_registers (&fctx->regcache, fctx->regs);
}
regcache = &fctx->regcache;
@@ -4722,7 +4722,7 @@ get_context_regcache (struct tracepoint_hit_ctx *ctx)
{
sctx->regcache_initted = 1;
sctx->regcache.initialize (ipa_tdesc, sctx->regspace);
- sctx->regcache.supply_regblock (nullptr);
+ sctx->regcache.discard ();
/* Pass down the tracepoint address, because REGS doesn't
include the PC, but we know what it must have been. */
supply_static_tracepoint_registers (&sctx->regcache,
@@ -5179,8 +5179,8 @@ fetch_traceframe_registers (int tfnum, struct regcache *regcache, int regnum)
dataptr = traceframe_find_regblock (tframe, tfnum);
if (dataptr == NULL)
{
- /* Mark registers unavailable. */
- regcache->supply_regblock (nullptr);
+ /* Wipe out the cache. */
+ regcache->discard ();

/* We can generally guess at a PC, although this will be
misleading for while-stepping frames and multi-location
--
2.25.1

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