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authorAntoine Tremblay <antoine.tremblay@ericsson.com>2017-01-09 12:39:07 -0500
committerAntoine Tremblay <antoine.tremblay@ericsson.com>2017-01-09 12:39:07 -0500
commit694b382c67a4fc656f30acbc74776c5e9cb53622 (patch)
treea63f5ac75142be9315e6f9adc52807fa9ba4b039
parenta5ec5e3fe1b8fe1395c79ff29052edad91266a76 (diff)
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Fix inferior memory reading in GDBServer for arm/aarch32
Before this patch, some functions would read the inferior memory with (*the_target)->read_memory, which returns the raw memory, rather than the shadowed memory. This is wrong since these functions do not expect to read a breakpoint instruction and can lead to invalid behavior. Use of raw memory in get_next_pcs_read_memory_unsigned_integer for example could lead to get_next_pc returning an invalid pc. Here's how this would happen: In non-stop: the user issues: thread 1 step& thread 2 step& thread 3 step& In a similar way as non-stop-fair-events.exp (threads are looping). GDBServer: linux_resume is called GDBServer has pending events, threads are not resumed and single-step breakpoint for thread 1 not installed. linux_wait_1 is called with a pending event on thread 2 at pc A GDBServer handles the event and calls proceed_all_lwps This calls proceed_one_lwp and installs single-step breakpoints on all the threads that need one. Now since thread 1 needs to install a single-step breakpoint and is at pc B (different than thread 2), a step-over is not initiated and get_next_pc is called to figure out the next instruction from pc B. However it may just be that thread 3 as a single step breakpoint at pc B. And thus get_next_pc fails. This situation is tested with non-stop-fair-events.exp. In other words, single-step breakpoints are installed in proceed_one_lwp for each thread. GDBserver proceeds two threads for resume_step, as requested by GDB, and the thread proceeded later may see the single-step breakpoints installed for the thread proceeded just now. Tested on gdbserver-native/-m{thumb,arm} no regressions. gdb/gdbserver/ChangeLog: * linux-aarch32-low.c (arm_breakpoint_kind_from_pc): Use target_read_memory. * linux-arm-low.c (get_next_pcs_read_memory_unsigned_integer): Likewise. (get_next_pcs_syscall_next_pc): Likewise.
-rw-r--r--gdb/gdbserver/ChangeLog7
-rw-r--r--gdb/gdbserver/linux-aarch32-low.c4
-rw-r--r--gdb/gdbserver/linux-arm-low.c5
3 files changed, 12 insertions, 4 deletions
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index d4d01e7..d3fba9b 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,10 @@
+2017-01-09 Antoine Tremblay <antoine.tremblay@ericsson.com>
+
+ * linux-aarch32-low.c (arm_breakpoint_kind_from_pc): Use
+ target_read_memory.
+ * linux-arm-low.c (get_next_pcs_read_memory_unsigned_integer): Likewise.
+ (get_next_pcs_syscall_next_pc): Likewise.
+
2016-12-23 Luis Machado <lgustavo@codesourcery.com>
* win32-i386-low.c: Fix incorrect reference to a couple source files.
diff --git a/gdb/gdbserver/linux-aarch32-low.c b/gdb/gdbserver/linux-aarch32-low.c
index 729b7cf..2b710ba 100644
--- a/gdb/gdbserver/linux-aarch32-low.c
+++ b/gdb/gdbserver/linux-aarch32-low.c
@@ -237,11 +237,11 @@ arm_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
*pcptr = UNMAKE_THUMB_ADDR (*pcptr);
/* Check whether we are replacing a thumb2 32-bit instruction. */
- if ((*the_target->read_memory) (*pcptr, buf, 2) == 0)
+ if (target_read_memory (*pcptr, buf, 2) == 0)
{
unsigned short inst1 = 0;
- (*the_target->read_memory) (*pcptr, (gdb_byte *) &inst1, 2);
+ target_read_memory (*pcptr, (gdb_byte *) &inst1, 2);
if (thumb_insn_size (inst1) == 4)
return ARM_BP_KIND_THUMB2;
}
diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
index b2b2258..fc2b348 100644
--- a/gdb/gdbserver/linux-arm-low.c
+++ b/gdb/gdbserver/linux-arm-low.c
@@ -263,7 +263,8 @@ get_next_pcs_read_memory_unsigned_integer (CORE_ADDR memaddr,
ULONGEST res;
res = 0;
- (*the_target->read_memory) (memaddr, (unsigned char *) &res, len);
+ target_read_memory (memaddr, (unsigned char *) &res, len);
+
return res;
}
@@ -804,7 +805,7 @@ get_next_pcs_syscall_next_pc (struct arm_get_next_pcs *self)
unsigned long this_instr;
unsigned long svc_operand;
- (*the_target->read_memory) (pc, (unsigned char *) &this_instr, 4);
+ target_read_memory (pc, (unsigned char *) &this_instr, 4);
svc_operand = (0x00ffffff & this_instr);
if (svc_operand) /* OABI. */