* [PATCH] gdb/csky add unwinder for long branch cases
@ 2022-08-31 11:42 Jiangshuai Li
0 siblings, 0 replies; only message in thread
From: Jiangshuai Li @ 2022-08-31 11:42 UTC (permalink / raw)
To: gdb-patches; +Cc: Jiangshuai Li
There are two sequences of instructions for long branch:
1. jmpi [pc+4] //insn code: 0xeac00001
.long addr
2. lrw t1, [pc+8] //insn code: 0xea8d0002
jmp t1 //insn code: 0x7834
nop //insn code: 0x6c03
.long addr
---
gdb/csky-tdep.c | 60 ++++++++++++++++++++++++++++++++++++++++++++-----
gdb/csky-tdep.h | 5 +++++
2 files changed, 60 insertions(+), 5 deletions(-)
diff --git a/gdb/csky-tdep.c b/gdb/csky-tdep.c
index ba53c1b10ca..3cd7a775f8d 100644
--- a/gdb/csky-tdep.c
+++ b/gdb/csky-tdep.c
@@ -2358,21 +2358,71 @@ static const struct frame_unwind csky_unwind_cache = {
NULL
};
+static CORE_ADDR
+csky_check_long_branch (struct frame_info *frame, CORE_ADDR pc)
+{
+ gdb_byte buf[8];
+ struct gdbarch *gdbarch = get_frame_arch (frame);
+ enum bfd_endian byte_order_for_code
+ = gdbarch_byte_order_for_code (gdbarch);
+
+ if (target_read_memory (pc, buf, 8) == 0)
+ {
+ unsigned int data0
+ = extract_unsigned_integer (buf, 4, byte_order_for_code);
+ unsigned int data1
+ = extract_unsigned_integer (buf + 4, 4, byte_order_for_code);
+
+ /* Case: jmpi [pc+4] : 0xeac00001
+ .long addr */
+ if (data0 == CSKY_JMPI_PC_4)
+ return data1;
+
+ /* Case: lrw t1, [pc+8] : 0xea8d0002
+ jmp t1 : 0x7834
+ nop : 0x6c03
+ .long addr */
+ if ((data0 == CSKY_LRW_T1_PC_8) && (data1 == CSKY_JMP_T1_VS_NOP))
+ {
+ if (target_read_memory (pc + 8, buf, 4) == 0)
+ return extract_unsigned_integer (buf, 4, byte_order_for_code);
+ }
+ return 0;
+ }
+
+ return 0;
+}
static int
csky_stub_unwind_sniffer (const struct frame_unwind *self,
- struct frame_info *this_frame,
- void **this_prologue_cache)
+ struct frame_info *this_frame,
+ void **this_prologue_cache)
{
- CORE_ADDR addr_in_block;
+ CORE_ADDR addr_in_block, pc;
+ gdb_byte dummy[4];
+ const char *name;
+ CORE_ADDR start_addr;
+ /* Get pc */
addr_in_block = get_frame_address_in_block (this_frame);
+ pc = get_frame_pc (this_frame);
- if (find_pc_partial_function (addr_in_block, NULL, NULL, NULL) == 0
- || in_plt_section (addr_in_block))
+ if (in_plt_section (addr_in_block)
+ || target_read_memory (pc, dummy, 4) != 0)
return 1;
+ /* Find the starting address and name of the function containing the PC. */
+ if (find_pc_partial_function (pc, &name, &start_addr, NULL) == 0)
+ {
+ start_addr = csky_check_long_branch (this_frame, pc);
+ /* if not long branch, return 0. */
+ if (start_addr != 0)
+ return 1;
+
+ return 0;
+ }
+
return 0;
}
diff --git a/gdb/csky-tdep.h b/gdb/csky-tdep.h
index f845b9ab744..dbdcd15b3a7 100644
--- a/gdb/csky-tdep.h
+++ b/gdb/csky-tdep.h
@@ -385,4 +385,9 @@ enum csky_regnum
/* Macro for kernel 4.x */
#define CSKY_MOVI_R7_139 0x008bea07
+/* Macro for check long branch. */
+#define CSKY_JMPI_PC_4 0x1eac0
+#define CSKY_LRW_T1_PC_8 0x2ea8d
+#define CSKY_JMP_T1_VS_NOP 0x6c037834
+
#endif
--
2.25.1
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