[binutils-gdb] gdb/arm: Sync sp with other *sp registers

[binutils-gdb] gdb/arm: Sync sp with other *sp registers

[Yvan Roux]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a6e4a48c02acf29d6bec2ff63fc909b57cf4bc78

commit a6e4a48c02acf29d6bec2ff63fc909b57cf4bc78
Author: Yvan Roux <yvan.roux@foss.st.com>
Date:   Mon Jul 25 15:26:24 2022 +0200

    gdb/arm: Sync sp with other *sp registers
    
    For Arm Cortex-M33 with security extensions, there are 4 different
    stack pointers (msp_s, msp_ns, psp_s, psp_ns), without security
    extensions and for other Cortex-M targets, there are 2 different
    stack pointers (msp and psp).
    
    With this patch, sp will always be in sync with one of the real stack
    pointers on Arm targets that contain more than one stack pointer.
    
    Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
    Signed-off-by: Yvan Roux <yvan.roux@foss.st.com>

Diff:
---
 gdb/arm-tdep.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 7d0944f9e3f..7d8d040f8f1 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -3815,6 +3815,78 @@ arm_dwarf2_prev_register (struct frame_info *this_frame, void **this_cache,
       cpsr = reconstruct_t_bit (gdbarch, lr, cpsr);
       return frame_unwind_got_constant (this_frame, regnum, cpsr);
     }
+  else if (arm_is_alternative_sp_register (tdep, regnum))
+    {
+      /* Handle the alternative SP registers on Cortex-M.  */
+      bool override_with_sp_value = false;
+      CORE_ADDR val;
+
+      if (tdep->have_sec_ext)
+	{
+	  CORE_ADDR sp
+	    = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
+	  CORE_ADDR msp_s
+	    = get_frame_register_unsigned (this_frame,
+					   tdep->m_profile_msp_s_regnum);
+	  CORE_ADDR msp_ns
+	    = get_frame_register_unsigned (this_frame,
+					   tdep->m_profile_msp_ns_regnum);
+	  CORE_ADDR psp_s
+	    = get_frame_register_unsigned (this_frame,
+					   tdep->m_profile_psp_s_regnum);
+	  CORE_ADDR psp_ns
+	    = get_frame_register_unsigned (this_frame,
+					   tdep->m_profile_psp_ns_regnum);
+
+	  bool is_msp = (regnum == tdep->m_profile_msp_regnum)
+	    && (msp_s == sp || msp_ns == sp);
+	  bool is_msp_s = (regnum == tdep->m_profile_msp_s_regnum)
+	    && (msp_s == sp);
+	  bool is_msp_ns = (regnum == tdep->m_profile_msp_ns_regnum)
+	    && (msp_ns == sp);
+	  bool is_psp = (regnum == tdep->m_profile_psp_regnum)
+	    && (psp_s == sp || psp_ns == sp);
+	  bool is_psp_s = (regnum == tdep->m_profile_psp_s_regnum)
+	    && (psp_s == sp);
+	  bool is_psp_ns = (regnum == tdep->m_profile_psp_ns_regnum)
+	    && (psp_ns == sp);
+
+	  override_with_sp_value = is_msp || is_msp_s || is_msp_ns
+	    || is_psp || is_psp_s || is_psp_ns;
+
+	}
+      else if (tdep->is_m)
+	{
+	  CORE_ADDR sp
+	    = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
+	  CORE_ADDR msp
+	    = get_frame_register_unsigned (this_frame,
+					   tdep->m_profile_msp_regnum);
+	  CORE_ADDR psp
+	    = get_frame_register_unsigned (this_frame,
+					   tdep->m_profile_psp_regnum);
+
+	  bool is_msp = (regnum == tdep->m_profile_msp_regnum) && (sp == msp);
+	  bool is_psp = (regnum == tdep->m_profile_psp_regnum) && (sp == psp);
+
+	  override_with_sp_value = is_msp || is_psp;
+	}
+
+      if (override_with_sp_value)
+	{
+	  /* Use value of SP from previous frame.  */
+	  struct frame_info *prev_frame = get_prev_frame (this_frame);
+	  if (prev_frame)
+	    val = get_frame_register_unsigned (prev_frame, ARM_SP_REGNUM);
+	  else
+	    val = get_frame_base (this_frame);
+	}
+      else
+	/* Use value for the register from previous frame.  */
+	val = get_frame_register_unsigned (this_frame, regnum);
+
+      return frame_unwind_got_constant (this_frame, regnum, val);
+    }
 
   internal_error (__FILE__, __LINE__,
 		  _("Unexpected register %d"), regnum);
@@ -4934,6 +5006,8 @@ arm_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
 			   struct dwarf2_frame_state_reg *reg,
 			   struct frame_info *this_frame)
 {
+  arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);
+
   if (is_pacbti_pseudo (gdbarch, regnum))
     {
       /* Initialize RA_AUTH_CODE to zero.  */
@@ -4950,6 +5024,12 @@ arm_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
     }
   else if (regnum == ARM_SP_REGNUM)
     reg->how = DWARF2_FRAME_REG_CFA;
+  else if (arm_is_alternative_sp_register (tdep, regnum))
+    {
+      /* Handle the alternative SP registers on Cortex-M.  */
+      reg->how = DWARF2_FRAME_REG_FN;
+      reg->loc.fn = arm_dwarf2_prev_register;
+    }
 }
 
 /* Given BUF, which is OLD_LEN bytes ending at ENDADDR, expand