* [PATCH] gdb/arm: Properly unwind S-registers for exception frames
@ 2022-10-10 18:09 Torbjörn SVENSSON
0 siblings, 0 replies; only message in thread
From: Torbjörn SVENSSON @ 2022-10-10 18:09 UTC (permalink / raw)
To: gdb-patches
For each D-register, there are 2 S-registers. In the GDB
architecture, the S-registers are implemented as pseudo registers.
As the value for the S-registers can be stacked, the value needs to
be extracted from the corresponding D-register and returned in the
associated prev_register function.
Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
---
gdb/arm-tdep.c | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)
diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index d357066653b..7168e2a5edc 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -261,6 +261,8 @@ static void arm_neon_quad_write (struct gdbarch *gdbarch,
static CORE_ADDR
arm_get_next_pcs_syscall_next_pc (struct arm_get_next_pcs *self);
+static bool is_s_pseudo (struct gdbarch *gdbarch, int regnum);
+
/* get_next_pcs operations. */
static struct arm_get_next_pcs_ops arm_get_next_pcs_ops = {
@@ -3726,8 +3728,8 @@ arm_m_exception_prev_register (struct frame_info *this_frame,
cache = (struct arm_prologue_cache *) *this_cache;
/* The value was already reconstructed into PREV_SP. */
- arm_gdbarch_tdep *tdep
- = gdbarch_tdep<arm_gdbarch_tdep> (get_frame_arch (this_frame));
+ struct gdbarch *gdbarch = get_frame_arch (this_frame);
+ arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);
if (prev_regnum == ARM_SP_REGNUM)
return frame_unwind_got_constant (this_frame, prev_regnum,
arm_cache_get_prev_sp_value (cache, tdep));
@@ -3756,7 +3758,6 @@ arm_m_exception_prev_register (struct frame_info *this_frame,
pattern. */
if (prev_regnum == ARM_PS_REGNUM)
{
- struct gdbarch *gdbarch = get_frame_arch (this_frame);
struct value *value = trad_frame_get_prev_register (this_frame,
cache->saved_regs,
ARM_PC_REGNUM);
@@ -3770,6 +3771,30 @@ arm_m_exception_prev_register (struct frame_info *this_frame,
return frame_unwind_got_constant (this_frame, ARM_PS_REGNUM, xpsr);
}
+ /* If we are asked to unwind Sn, unwind Dm where m is n/2 and take the
+ corresponding part of the D register. */
+ if (is_s_pseudo (gdbarch, prev_regnum))
+ {
+ int single_regnum = prev_regnum - tdep->s_pseudo_base;
+ int double_regnum = ARM_D0_REGNUM + single_regnum / 2;
+ int offset;
+
+ struct value *value = trad_frame_get_prev_register (this_frame,
+ cache->saved_regs,
+ double_regnum);
+
+ gdb::array_view<const gdb_byte> raw = value_contents (value);
+
+ /* s0 is always the least significant half of d0. */
+ if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
+ offset = (single_regnum & 1) ? 0 : 4;
+ else
+ offset = (single_regnum & 1) ? 4 : 0;
+
+ return frame_unwind_got_bytes (this_frame, prev_regnum,
+ raw.slice (offset).data ());
+ }
+
return trad_frame_get_prev_register (this_frame, cache->saved_regs,
prev_regnum);
}
--
2.25.1
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