[PATCH v3 06/10] Replace breakpoint_reinsert_addr by get_next_pcs operation in GDBServer.

Antoine Tremblay
2015-11-23T14:14:28Z

In this v3:

* Changed get_next_pcs signature.
* Remove common/get-next-pcs.h file.
* CORE_ADDR is now in linux-low.h temporarely.

---

This patch in preparation for software single step support on ARM. It refactors
breakpoint_reinsert_addr into get_next_pcs so that multiple location can be
returned.

When software single stepping there can be multiple possible next addresses
because we're stepping over a conditional branch instruction for example.

The operation get_next_pcs handles that by returning a vector of all the
possible next addresses.

Software breakpoints are installed at each location returned.

No regressions, tested on ubuntu 14.04 ARMv7 and x86.
With gdbserver-{native,extended} / { -marm -mthumb }

gdb/gdbserver/ChangeLog:
* linux-aarch64-low.c (struct linux_target_ops): Rename
breakpoint_reinsert_addr to get_next_pcs.
* linux-arm-low.c (struct linux_target_ops): Likewise.
* linux-bfin-low.c (struct linux_target_ops): Likewise.
* linux-cris-low.c (struct linux_target_ops): Likewise.
* linux-crisv32-low.c (struct linux_target_ops): Likewise.
* linux-low.c (can_software_single_step): Likewise.
(install_software_single_step_breakpoints): New function.
(start_step_over): Use install_software_single_step_breakpoints.
* linux-low.h: New CORE_ADDR vector.
(struct linux_target_ops) Rename breakpoint_reinsert_addr to
get_next_pcs.
* linux-mips-low.c (struct linux_target_ops): Likewise.
* linux-nios2-low.c (struct linux_target_ops): Likewise.
* linux-sparc-low.c (struct linux_target_ops): Likewise.
---
gdb/gdbserver/linux-aarch64-low.c | 2 +-
gdb/gdbserver/linux-arm-low.c | 2 +-
gdb/gdbserver/linux-bfin-low.c | 2 +-
gdb/gdbserver/linux-cris-low.c | 2 +-
gdb/gdbserver/linux-crisv32-low.c | 2 +-
gdb/gdbserver/linux-low.c | 28 ++++++++++++++++++++++++----
gdb/gdbserver/linux-low.h | 5 ++++-
gdb/gdbserver/linux-mips-low.c | 2 +-
gdb/gdbserver/linux-nios2-low.c | 2 +-
gdb/gdbserver/linux-sparc-low.c | 2 +-
10 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c
index 17798ff..3b8a9ad 100644
--- a/gdb/gdbserver/linux-aarch64-low.c
+++ b/gdb/gdbserver/linux-aarch64-low.c
@@ -2963,7 +2963,7 @@ struct linux_target_ops the_low_target =
aarch64_set_pc,
NULL, /* breakpoint_kind_from_pc */
aarch64_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
0, /* decr_pc_after_break */
aarch64_breakpoint_at,
aarch64_supports_z_point_type,
diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
index 885aec9..78a4c8f 100644
--- a/gdb/gdbserver/linux-arm-low.c
+++ b/gdb/gdbserver/linux-arm-low.c
@@ -1032,7 +1032,7 @@ struct linux_target_ops the_low_target = {
arm_set_pc,
arm_breakpoint_kind_from_pc,
arm_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
0,
arm_breakpoint_at,
arm_supports_z_point_type,
diff --git a/gdb/gdbserver/linux-bfin-low.c b/gdb/gdbserver/linux-bfin-low.c
index 912d253..1de2f78 100644
--- a/gdb/gdbserver/linux-bfin-low.c
+++ b/gdb/gdbserver/linux-bfin-low.c
@@ -141,7 +141,7 @@ struct linux_target_ops the_low_target = {
bfin_set_pc,
NULL, /* breakpoint_kind_from_pc */
bfin_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
2,
bfin_breakpoint_at,
NULL, /* supports_z_point_type */
diff --git a/gdb/gdbserver/linux-cris-low.c b/gdb/gdbserver/linux-cris-low.c
index 9f4519c..6902a45 100644
--- a/gdb/gdbserver/linux-cris-low.c
+++ b/gdb/gdbserver/linux-cris-low.c
@@ -139,7 +139,7 @@ struct linux_target_ops the_low_target = {
cris_set_pc,
NULL, /* breakpoint_kind_from_pc */
cris_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
0,
cris_breakpoint_at,
};
diff --git a/gdb/gdbserver/linux-crisv32-low.c b/gdb/gdbserver/linux-crisv32-low.c
index 2404d0e..28c1981 100644
--- a/gdb/gdbserver/linux-crisv32-low.c
+++ b/gdb/gdbserver/linux-crisv32-low.c
@@ -422,7 +422,7 @@ struct linux_target_ops the_low_target = {
cris_set_pc,
NULL, /* breakpoint_kind_from_pc */
cris_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
0,
cris_breakpoint_at,
cris_supports_z_point_type,
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index ce9cc2e..85a8e3f 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -281,12 +281,12 @@ can_hardware_single_step (void)
}

/* True if the low target can software single-step. Such targets
- implement the BREAKPOINT_REINSERT_ADDR callback. */
+ implement the GET_NEXT_PCS callback. */

static int
can_software_single_step (void)
{
- return (the_low_target.breakpoint_reinsert_addr != NULL);
+ return (the_low_target.get_next_pcs != NULL);
}

/* True if the low target supports memory breakpoints. If so, we'll
@@ -3876,6 +3876,27 @@ enqueue_pending_signal (struct lwp_info *lwp, int signal, siginfo_t *info)
lwp->pending_signals = p_sig;
}

+/* Install breakpoints for software single stepping. */
+
+static void
+install_software_single_step_breakpoints (struct lwp_info *lwp)
+{
+ int i;
+ CORE_ADDR pc;
+ struct regcache *regcache = get_thread_regcache (current_thread, 1);
+ VEC (CORE_ADDR) *next_pcs = NULL;
+
+ pc = get_pc (lwp);
+ next_pcs = (*the_low_target.get_next_pcs) (pc, regcache);
+
+ for (i = 0; VEC_iterate (CORE_ADDR, next_pcs, i, pc); ++i)
+ {
+ set_reinsert_breakpoint (pc);
+ }
+
+ VEC_free (CORE_ADDR, next_pcs);
+}
+
/* Resume execution of LWP. If STEP is nonzero, single-step it. If
SIGNAL is nonzero, give it that signal. */

@@ -4439,8 +4460,7 @@ start_step_over (struct lwp_info *lwp)
}
else if (can_software_single_step ())
{
- CORE_ADDR raddr = (*the_low_target.breakpoint_reinsert_addr) ();
- set_reinsert_breakpoint (raddr);
+ install_software_single_step_breakpoints (lwp);
step = 0;
}
else
diff --git a/gdb/gdbserver/linux-low.h b/gdb/gdbserver/linux-low.h
index d60d97d..ee8d88f 100644
--- a/gdb/gdbserver/linux-low.h
+++ b/gdb/gdbserver/linux-low.h
@@ -124,6 +124,8 @@ struct process_info_private

struct lwp_info;

+DEF_VEC_I (CORE_ADDR);
+
struct linux_target_ops
{
/* Architecture-specific setup. */
@@ -153,7 +155,8 @@ struct linux_target_ops
/* See target.h for details. */
const gdb_byte *(*sw_breakpoint_from_kind) (int kind, int *size);

- CORE_ADDR (*breakpoint_reinsert_addr) (void);
+ /* Find the next possible PCs after the current instruction executes. */
+ VEC (CORE_ADDR) *(*get_next_pcs) (CORE_ADDR pc, struct regcache *regcache);

int decr_pc_after_break;
int (*breakpoint_at) (CORE_ADDR pc);
diff --git a/gdb/gdbserver/linux-mips-low.c b/gdb/gdbserver/linux-mips-low.c
index b8f8805..9da4610 100644
--- a/gdb/gdbserver/linux-mips-low.c
+++ b/gdb/gdbserver/linux-mips-low.c
@@ -880,7 +880,7 @@ struct linux_target_ops the_low_target = {
mips_set_pc,
NULL, /* breakpoint_kind_from_pc */
mips_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
0,
mips_breakpoint_at,
mips_supports_z_point_type,
diff --git a/gdb/gdbserver/linux-nios2-low.c b/gdb/gdbserver/linux-nios2-low.c
index 9380c3b..1accc03 100644
--- a/gdb/gdbserver/linux-nios2-low.c
+++ b/gdb/gdbserver/linux-nios2-low.c
@@ -267,7 +267,7 @@ struct linux_target_ops the_low_target =
nios2_set_pc,
NULL, /* breakpoint_kind_from_pc */
nios2_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
0,
nios2_breakpoint_at,
};
diff --git a/gdb/gdbserver/linux-sparc-low.c b/gdb/gdbserver/linux-sparc-low.c
index 54a849c..bfdd8c1 100644
--- a/gdb/gdbserver/linux-sparc-low.c
+++ b/gdb/gdbserver/linux-sparc-low.c
@@ -320,7 +320,7 @@ struct linux_target_ops the_low_target = {
NULL,
NULL, /* breakpoint_kind_from_pc */
sparc_sw_breakpoint_from_kind,
- NULL, /* breakpoint_reinsert_addr */
+ NULL, /* get_next_pcs */
0,
sparc_breakpoint_at,
NULL, /* supports_z_point_type */
--
2.6.3