From 633785ff2876e5bf03070a235d3e8cfe94cbf6bd Mon Sep 17 00:00:00 2001 From: Markus Metzger Date: Wed, 24 Apr 2013 13:24:11 +0200 Subject: [PATCH] record-btrace: provide xfer_partial target method Provide the xfer_partial target method for the btrace record target. Only allow memory read accesses to readonly memory while we're replaying, except for inserting and removing breakpoints. 2014-01-16 Markus Metzger * record-btrace.c (record_btrace_xfer_partial) (record_btrace_insert_breakpoint, record_btrace_remove_breakpoint) (record_btrace_allow_memory_access): New. (init_record_btrace_ops): Initialize new methods. * target.c (raw_memory_xfer_partial): Bail out if target reports that this memory is not available. --- gdb/ChangeLog | 9 ++++ gdb/record-btrace.c | 112 ++++++++++++++++++++++++++++++++++++++++++++ gdb/target.c | 4 ++ 3 files changed, 125 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index b4dd9c67327..29f00d851c6 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,12 @@ +2014-01-16 Markus Metzger + + * record-btrace.c (record_btrace_xfer_partial) + (record_btrace_insert_breakpoint, record_btrace_remove_breakpoint) + (record_btrace_allow_memory_access): New. + (init_record_btrace_ops): Initialize new methods. + * target.c (raw_memory_xfer_partial): Bail out if target reports + that this memory is not available. + 2014-01-16 Markus Metzger * target.h (target_ops) diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c index 146d2739c96..a12dba18b71 100644 --- a/gdb/record-btrace.c +++ b/gdb/record-btrace.c @@ -41,6 +41,9 @@ static struct target_ops record_btrace_ops; /* A new thread observer enabling branch tracing for the new thread. */ static struct observer *record_btrace_thread_observer; +/* Temporarily allow memory accesses. */ +static int record_btrace_allow_memory_access; + /* Print a record-btrace debug message. Use do ... while (0) to avoid ambiguities when used in if statements. */ @@ -752,6 +755,112 @@ record_btrace_is_replaying (void) return 0; } +/* The to_xfer_partial method of target record-btrace. */ + +static LONGEST +record_btrace_xfer_partial (struct target_ops *ops, enum target_object object, + const char *annex, gdb_byte *readbuf, + const gdb_byte *writebuf, ULONGEST offset, + ULONGEST len) +{ + struct target_ops *t; + + /* Filter out requests that don't make sense during replay. */ + if (!record_btrace_allow_memory_access && record_btrace_is_replaying ()) + { + switch (object) + { + case TARGET_OBJECT_MEMORY: + { + struct target_section *section; + + /* We do not allow writing memory in general. */ + if (writebuf != NULL) + return TARGET_XFER_E_UNAVAILABLE; + + /* We allow reading readonly memory. */ + section = target_section_by_addr (ops, offset); + if (section != NULL) + { + /* Check if the section we found is readonly. */ + if ((bfd_get_section_flags (section->the_bfd_section->owner, + section->the_bfd_section) + & SEC_READONLY) != 0) + { + /* Truncate the request to fit into this section. */ + len = min (len, section->endaddr - offset); + break; + } + } + + return TARGET_XFER_E_UNAVAILABLE; + } + } + } + + /* Forward the request. */ + for (ops = ops->beneath; ops != NULL; ops = ops->beneath) + if (ops->to_xfer_partial != NULL) + return ops->to_xfer_partial (ops, object, annex, readbuf, writebuf, + offset, len); + + return TARGET_XFER_E_UNAVAILABLE; +} + +/* The to_insert_breakpoint method of target record-btrace. */ + +static int +record_btrace_insert_breakpoint (struct target_ops *ops, + struct gdbarch *gdbarch, + struct bp_target_info *bp_tgt) +{ + volatile struct gdb_exception except; + int old, ret; + + /* Inserting breakpoints requires accessing memory. Allow it for the + duration of this function. */ + old = record_btrace_allow_memory_access; + record_btrace_allow_memory_access = 1; + + ret = 0; + TRY_CATCH (except, RETURN_MASK_ALL) + ret = forward_target_insert_breakpoint (ops->beneath, gdbarch, bp_tgt); + + record_btrace_allow_memory_access = old; + + if (except.reason < 0) + throw_exception (except); + + return ret; +} + +/* The to_remove_breakpoint method of target record-btrace. */ + +static int +record_btrace_remove_breakpoint (struct target_ops *ops, + struct gdbarch *gdbarch, + struct bp_target_info *bp_tgt) +{ + volatile struct gdb_exception except; + int old, ret; + + /* Removing breakpoints requires accessing memory. Allow it for the + duration of this function. */ + old = record_btrace_allow_memory_access; + record_btrace_allow_memory_access = 1; + + ret = 0; + TRY_CATCH (except, RETURN_MASK_ALL) + ret = forward_target_remove_breakpoint (ops->beneath, gdbarch, bp_tgt); + + record_btrace_allow_memory_access = old; + + if (except.reason < 0) + throw_exception (except); + + return ret; +} + /* The to_fetch_registers method of target record-btrace. */ static void @@ -929,6 +1038,9 @@ init_record_btrace_ops (void) ops->to_call_history_from = record_btrace_call_history_from; ops->to_call_history_range = record_btrace_call_history_range; ops->to_record_is_replaying = record_btrace_is_replaying; + ops->to_xfer_partial = record_btrace_xfer_partial; + ops->to_remove_breakpoint = record_btrace_remove_breakpoint; + ops->to_insert_breakpoint = record_btrace_insert_breakpoint; ops->to_fetch_registers = record_btrace_fetch_registers; ops->to_store_registers = record_btrace_store_registers; ops->to_prepare_to_store = record_btrace_prepare_to_store; diff --git a/gdb/target.c b/gdb/target.c index 612d909f045..d9c27b88c18 100644 --- a/gdb/target.c +++ b/gdb/target.c @@ -1406,6 +1406,10 @@ raw_memory_xfer_partial (struct target_ops *ops, void *readbuf, if (res > 0) break; + /* Stop if the target reports that the memory is not available. */ + if (res == TARGET_XFER_E_UNAVAILABLE) + break; + /* We want to continue past core files to executables, but not past a running target's memory. */ if (ops->to_has_all_memory (ops)) -- 2.30.2