[PATCH 2/2] arm-tdep.c: Refactor displaced stepping relocation functions

Simon Marchi
2016-02-25T15:47:44Z

A small refactor so that arm_process_displaced_insn is the only function
specific to GDB. All functions called from this one will eventually be
moved to common/, so they need to be free of anything GDB-specific. I
also renamed those functions from "process_displaced" to "relocate",
since they won't be used exclusively for displaced stepping anymore.

The call tree ends up like this:

- arm_process_displaced_insn
- arm_relocate_insn_arm
...
- arm_relocate_insn_thumb_32bit
...
- arm_relocate_insn_thumb_16bit
...

gdb/ChangeLog:

* arm-tdep.c (thumb_process_displaced_16bit_insn): Rename to...
(arm_relocate_insn_thumb_16bit): ... this, and add return error
code.
(thumb_process_displaced_32bit_insn): Rename to...
(arm_relocate_insn_thumb_32bit): ... this, and add return error
code.
(thumb_process_displaced_insn): Remove.
(arm_relocate_insn_arm): New function, extracted mostly from...
(arm_process_displaced_insn): ... this. Refactor to adapt to
other functions changes.
---
gdb/arm-tdep.c | 122 ++++++++++++++++++++++++++++++---------------------------
1 file changed, 64 insertions(+), 58 deletions(-)

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 43b61c2..ef48a90 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -7111,9 +7111,8 @@ thumb_copy_pop_pc_16bit (uint16_t insn1, struct arm_insn_reloc_data *data)
return 0;
}

-static void
-thumb_process_displaced_16bit_insn (uint16_t insn1,
- struct arm_insn_reloc_data *data)
+static int
+arm_relocate_insn_thumb_16bit (uint16_t insn1, struct arm_insn_reloc_data *data)
{
unsigned short op_bit_12_15 = bits (insn1, 12, 15);
unsigned short op_bit_10_11 = bits (insn1, 10, 11);
@@ -7202,9 +7201,7 @@ thumb_process_displaced_16bit_insn (uint16_t insn1,
err = 1;
}

- if (err)
- internal_error (__FILE__, __LINE__,
- _("thumb_process_displaced_16bit_insn: Instruction decode error"));
+ return err;
}

static int
@@ -7279,9 +7276,9 @@ decode_thumb_32bit_ld_mem_hints (uint16_t insn1, uint16_t insn2,
return 0;
}

-static void
-thumb_process_displaced_32bit_insn (uint16_t insn1, uint16_t insn2,
- struct arm_insn_reloc_data *data)
+static int
+arm_relocate_insn_thumb_32bit (uint16_t insn1, uint16_t insn2,
+ struct arm_insn_reloc_data *data)
{
int err = 0;
unsigned short op = bit (insn2, 15);
@@ -7393,34 +7390,41 @@ thumb_process_displaced_32bit_insn (uint16_t insn1, uint16_t insn2,
err = 1;
}

- if (err)
- internal_error (__FILE__, __LINE__,
- _("thumb_process_displaced_32bit_insn: Instruction decode error"));
+ return err;

}

-static void
-thumb_process_displaced_insn (CORE_ADDR from, struct arm_insn_reloc_data *data)
+static int
+arm_relocate_insn_arm (uint32_t insn, struct arm_insn_reloc_data *data)
{
- enum bfd_endian byte_order_for_code
- = gdbarch_byte_order_for_code (data->gdbarch);
- uint16_t insn1
- = read_memory_unsigned_integer (from, 2, byte_order_for_code);
+ int err = 1;

- if (debug_displaced)
- fprintf_unfiltered (gdb_stdlog, "displaced: process thumb insn %.4x "
- "at %.8lx\n", insn1, (unsigned long) from);
-
- data->dsc->is_thumb = 1;
- data->dsc->insn_size = thumb_insn_size (insn1);
- if (thumb_insn_size (insn1) == 4)
+ if ((insn & 0xf0000000) == 0xf0000000)
+ err = arm_decode_unconditional (insn, data);
+ else switch (((insn & 0x10) >> 4) | ((insn & 0xe000000) >> 24))
{
- uint16_t insn2
- = read_memory_unsigned_integer (from + 2, 2, byte_order_for_code);
- thumb_process_displaced_32bit_insn (insn1, insn2, data);
+ case 0x0: case 0x1: case 0x2: case 0x3:
+ err = arm_decode_dp_misc (insn, data);
+ break;
+
+ case 0x4: case 0x5: case 0x6:
+ err = arm_decode_ld_st_word_ubyte (insn, data);
+ break;
+
+ case 0x7:
+ err = arm_decode_media (insn, data);
+ break;
+
+ case 0x8: case 0x9: case 0xa: case 0xb:
+ err = arm_decode_b_bl_ldmstm (insn, data);
+ break;
+
+ case 0xc: case 0xd: case 0xe: case 0xf:
+ err = arm_decode_svc_copro (insn, data);
+ break;
}
- else
- thumb_process_displaced_16bit_insn (insn1, data);
+
+ return err;
}

void
@@ -7430,7 +7434,6 @@ arm_process_displaced_insn (struct gdbarch *gdbarch, CORE_ADDR from,
{
int err = 0;
enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
- uint32_t insn;
struct arm_insn_reloc_data reloc_data = {
dsc,
gdbarch,
@@ -7445,40 +7448,43 @@ arm_process_displaced_insn (struct gdbarch *gdbarch, CORE_ADDR from,
dsc->cleanup = NULL;
dsc->wrote_to_pc = 0;

- if (!displaced_in_arm_mode (regs))
- return thumb_process_displaced_insn (from, &reloc_data);
+ if (displaced_in_arm_mode (regs))
+ {
+ uint32_t insn
+ = read_memory_unsigned_integer (from, 4, byte_order_for_code);

- dsc->is_thumb = 0;
- dsc->insn_size = 4;
- insn = read_memory_unsigned_integer (from, 4, byte_order_for_code);
- if (debug_displaced)
- fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx "
- "at %.8lx\n", (unsigned long) insn,
- (unsigned long) from);
+ if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx "
+ "at %.8lx\n", (unsigned long) insn,
+ (unsigned long) from);

- if ((insn & 0xf0000000) == 0xf0000000)
- err = arm_decode_unconditional (insn, &reloc_data);
- else switch (((insn & 0x10) >> 4) | ((insn & 0xe000000) >> 24))
+ dsc->is_thumb = 0;
+ dsc->insn_size = 4;
+
+ err = arm_relocate_insn_arm (insn, &reloc_data);
+ }
+ else
{
- case 0x0: case 0x1: case 0x2: case 0x3:
- err = arm_decode_dp_misc (insn, &reloc_data);
- break;
+ uint16_t insn1
+ = read_memory_unsigned_integer (from, 2, byte_order_for_code);
+ unsigned int insn_size = thumb_insn_size (insn1);

- case 0x4: case 0x5: case 0x6:
- err = arm_decode_ld_st_word_ubyte (insn, &reloc_data);
- break;
+ if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: process thumb insn %.4x "
+ "at %.8lx\n", insn1, (unsigned long) from);

- case 0x7:
- err = arm_decode_media (insn, &reloc_data);
- break;
+ dsc->is_thumb = 1;
+ dsc->insn_size = insn_size;

- case 0x8: case 0x9: case 0xa: case 0xb:
- err = arm_decode_b_bl_ldmstm (insn, &reloc_data);
- break;
+ if (insn_size == 4)
+ {
+ uint16_t insn2
+ = read_memory_unsigned_integer (from + 2, 2, byte_order_for_code);

- case 0xc: case 0xd: case 0xe: case 0xf:
- err = arm_decode_svc_copro (insn, &reloc_data);
- break;
+ err = arm_relocate_insn_thumb_32bit (insn1, insn2, &reloc_data);
+ }
+ else
+ err = arm_relocate_insn_thumb_16bit (insn1, &reloc_data);
}

if (err)
--
2.5.1