Re: [PATCH 2/3 v4] Process record support for PowerPC

Wei-cheng Wang
2015-01-19T16:10:16Z

On 2015/1/19 ä¸‹åˆ 03:48, Joel Brobecker wrote:
>> Using %s+paddress instead of %lx+long in this patch.
> The change looks fine to me, but there is no ChangeLog.

Hi Joel,

ChangeLog is in my last mail. Re-post below for your review.

2015-01-18 Wei-cheng Wang <cole945@gmail.com>

* rs6000-tdep.c (ppc_process_record_op4, ppc_process_record_op19,
ppc_process_record_op31, ppc_process_record_op59,
ppc_process_record_op60, ppc_process_record_op63,
ppc_process_record): Fix -Wformat warning.
* rs6000-tdep.c (rs6000_epilogue_frame_cache, ppc_process_record_op60):
Remove unused variables.

> Also, I ended glancing at some of the patches you recently pushed,
> and noticed that you added a lot of new functions for which there
> is no introductory comment describing the function's behavior and
> arguments. It is now mandatory that all new functions, no matter
> how trivial, have such introductory comment. Would you mind going
> back over your patches, and send a patch that adds the missing
> comments, please?

I've added the missing comments. See below.

Thanks,
Wei-cheng

2015-01-18 Wei-cheng Wang <cole945@gmail.com>

* ppc-linux-tdep.c (ppc_skip_trampoline_code,
ppc_canonicalize_syscall, ppc_linux_syscall_record,
ppc_linux_record_signal, ppc_init_linux_record_tdep): Add comments.
* ppc64-tdep.c (ppc64_skip_trampoline_code): Likewise.
* rs6000-tdep.c (rs6000_epilogue_frame_cache,
rs6000_epilogue_frame_this_id, rs6000_epilogue_frame_prev_register,
rs6000_epilogue_frame_sniffer, ppc_record_vsr, ppc_process_record_op4,
ppc_process_record_op19, ppc_process_record_op31,
ppc_process_record_op59, ppc_process_record_op60,
ppc_process_record_op63): Likewise.

From 26f1310335aace089f686a11a5e100ad166d4235 Mon Sep 17 00:00:00 2001
From: Wei-cheng Wang <cole945@gmail.com>
Date: Mon, 19 Jan 2015 23:34:07 +0800
Subject: [PATCH 2/2] Add missing comments in rs6000-tdep.c, ppc64-tdep.c and
ppc-linux-tdep.c.

---
gdb/ppc-linux-tdep.c | 26 ++++++++++++++++++++++----
gdb/ppc64-tdep.c | 5 ++++-
gdb/rs6000-tdep.c | 39 +++++++++++++++++++++++++++++++--------
4 files changed, 70 insertions(+), 13 deletions(-)

diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index 13bb479..4a37a27 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -305,7 +305,12 @@ powerpc_linux_in_dynsym_resolve_code (CORE_ADDR pc)
return 0;
}

-/* Follow PLT stub to actual routine. */
+/* Follow PLT stub to actual routine.
+
+ When the execution direction is EXEC_REVERSE, scan backward to
+ check whether we are in the middle of a PLT stub. Currently,
+ we only look-behind at most 4 instructions (the max length of PLT
+ stub sequence. */

static CORE_ADDR
ppc_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
@@ -791,11 +796,16 @@ ppc_linux_get_syscall_number (struct gdbarch *gdbarch,
static struct linux_record_tdep ppc_linux_record_tdep;
static struct linux_record_tdep ppc64_linux_record_tdep;

+/* ppc_canonicalize_syscall maps from the native PowerPC Linux set of
+ syscall ids into a canonical set of syscall ids used by process
+ record. (See arch/powerpc/include/uapi/asm/unistd.h in kernel tree.)
+ Return -1 if this system call is not supported by process record.
+ Otherwise, return the syscall number for preocess reocrd of given
+ SYSCALL. */
+
static enum gdb_syscall
ppc_canonicalize_syscall (int syscall)
{
- /* See arch/powerpc/include/uapi/asm/unistd.h */
-
if (syscall <= 165)
return syscall;
else if (syscall >= 167 && syscall <= 190) /* Skip query_module 166 */
@@ -821,6 +831,9 @@ ppc_canonicalize_syscall (int syscall)
return -1;
}

+/* Record registers which might be clobbered during system call.
+ Return 0 if succeed. */
+
static int
ppc_linux_syscall_record (struct regcache *regcache)
{
@@ -901,6 +914,9 @@ ppc_linux_syscall_record (struct regcache *regcache)
return 0;
}

+/* Record registers which might be clobbered during sinal handling.
+ Return 0 if succeed. */
+
static int
ppc_linux_record_signal (struct gdbarch *gdbarch, struct regcache *regcache,
enum gdb_signal signal)
@@ -1417,7 +1433,9 @@ static const struct frame_unwind ppu2spu_unwind = {
ppu2spu_prev_arch,
};

-/* Initialize linux_record_tdep if not initialized yet. */
+/* Initialize linux_record_tdep if not initialized yet.
+ WORDSIZE is 4 or 8 for 32- or 64-bit PowerPC Linux respectively.
+ Sizes of data structures are initilzied accordingly. */

static void
ppc_init_linux_record_tdep (struct linux_record_tdep *record_tdep,
diff --git a/gdb/ppc64-tdep.c b/gdb/ppc64-tdep.c
index 66d7b23..bb23b6a 100644
--- a/gdb/ppc64-tdep.c
+++ b/gdb/ppc64-tdep.c
@@ -449,7 +449,10 @@ ppc64_standard_linkage4_target (struct frame_info *frame,

/* Given that we've begun executing a call trampoline at PC, return
- the entry point of the function the trampoline will go to. */
+ the entry point of the function the trampoline will go to.
+
+ When the execution direction is EXEC_REVERSE, scan backward to
+ check whether we are in the middle of a PLT stub. */

CORE_ADDR
ppc64_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c
index 1dd6165..0a24881 100644
--- a/gdb/rs6000-tdep.c
+++ b/gdb/rs6000-tdep.c
@@ -3349,6 +3349,9 @@ static const struct frame_unwind rs6000_frame_unwind =
default_frame_sniffer
};

+/* Allocate and initialize a frame cache for an epilogue frame.
+ SP is restored and prev-PC is stored in LR. */
+
static struct rs6000_frame_cache *
rs6000_epilogue_frame_cache (struct frame_info *this_frame, void **this_cache)
{
@@ -3385,6 +3388,9 @@ rs6000_epilogue_frame_cache (struct frame_info *this_frame, void **this_cache)
return cache;
}

+/* Implementation of frame_unwind.this_id, as defined in frame_unwind.h.
+ Return the frame ID of an epilogue frame. */
+
static void
rs6000_epilogue_frame_this_id (struct frame_info *this_frame,
void **this_cache, struct frame_id *this_id)
@@ -3400,6 +3406,9 @@ rs6000_epilogue_frame_this_id (struct frame_info *this_frame,
(*this_id) = frame_id_build (info->base, pc);
}

+/* Implementation of frame_unwind.prev_register, as defined in frame_unwind.h.
+ Return the register value of REGNUM in previous frame. */
+
static struct value *
rs6000_epilogue_frame_prev_register (struct frame_info *this_frame,
void **this_cache, int regnum)
@@ -3409,6 +3418,9 @@ rs6000_epilogue_frame_prev_register (struct frame_info *this_frame,
return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
}

+/* Implementation of frame_unwind.sniffer, as defined in frame_unwind.h.
+ Check whether this an epilogue frame. */
+
static int
rs6000_epilogue_frame_sniffer (const struct frame_unwind *self,
struct frame_info *this_frame,
@@ -3422,6 +3434,9 @@ rs6000_epilogue_frame_sniffer (const struct frame_unwind *self,
return 0;
}

+/* Frame unwinder for epilogue frame. This is required for reverse step-over
+ a function without debug information. */
+
static const struct frame_unwind rs6000_epilogue_frame_unwind =
{
NORMAL_FRAME,
@@ -3668,7 +3683,9 @@ bfd_uses_spe_extensions (bfd *abfd)
#define PPC_XT(insn) ((PPC_TX (insn) << 5) | PPC_T (insn))
#define PPC_XER_NB(xer) (xer & 0x7f)

-/* Record Vector-Scalar Registers. */
+/* Record Vector-Scalar Registers.
+ For VSR less than 32, it's represented by an FPR and an VSR-upper register.
+ Otherwise, it's just a VR register. Record them accordingly. */

static int
ppc_record_vsr (struct regcache *regcache, struct gdbarch_tdep *tdep, int vsr)
@@ -3693,11 +3710,12 @@ ppc_record_vsr (struct regcache *regcache, struct gdbarch_tdep *tdep, int vsr)
return 0;
}

-/* Parse instructions of primary opcode-4. */
+/* Parse and record instructions primary opcode-4 at ADDR.
+ Return 0 if succeed. */

static int
ppc_process_record_op4 (struct gdbarch *gdbarch, struct regcache *regcache,
- CORE_ADDR addr, uint32_t insn)
+ CORE_ADDR addr, uint32_t insn)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
int ext = PPC_FIELD (insn, 21, 11);
@@ -3961,7 +3979,8 @@ ppc_process_record_op4 (struct gdbarch *gdbarch, struct regcache *regcache,
return -1;
}

-/* Parse instructions of primary opcode-19. */
+/* Parse and record instructions of primary opcode-19 at ADDR.
+ Return 0 if succeed. */

static int
ppc_process_record_op19 (struct gdbarch *gdbarch, struct regcache *regcache,
@@ -4004,7 +4023,8 @@ ppc_process_record_op19 (struct gdbarch *gdbarch, struct regcache *regcache,
return -1;
}

-/* Parse instructions of primary opcode-31. */
+/* Parse and record instructions of primary opcode-31 at ADDR.
+ Return 0 if succeed. */

static int
ppc_process_record_op31 (struct gdbarch *gdbarch, struct regcache *regcache,
@@ -4482,7 +4502,8 @@ UNKNOWN_OP:
return -1;
}

-/* Parse instructions of primary opcode-59. */
+/* Parse and record instructions of primary opcode-59 at ADDR.
+ Return 0 if succeed. */

static int
ppc_process_record_op59 (struct gdbarch *gdbarch, struct regcache *regcache,
@@ -4574,7 +4595,8 @@ ppc_process_record_op59 (struct gdbarch *gdbarch, struct regcache *regcache,
return -1;
}

-/* Parse instructions of primary opcode-60. */
+/* Parse and record instructions of primary opcode-60 at ADDR.
+ Return 0 if succeed. */

static int
ppc_process_record_op60 (struct gdbarch *gdbarch, struct regcache *regcache,
@@ -4856,7 +4878,8 @@ ppc_process_record_op60 (struct gdbarch *gdbarch, struct regcache *regcache,
return -1;
}

-/* Parse instructions of primary opcode-63. */
+/* Parse and record instructions of primary opcode-63 at ADDR.
+ Return 0 if succeed. */

static int
ppc_process_record_op63 (struct gdbarch *gdbarch, struct regcache *regcache,
--
1.9.1