[PATCH 2/3] gdb/arm: Track msp and psp

[Yvan Roux <yvan.roux@foss.st.com>]

For Arm Cortex-M33 with security extensions, there are 4 different
stack pointers (msp_s, msp_ns, psp_s, psp_ns).  To be compatible
with earlier Cortex-M derivates, the msp and psp registers are
aliases for one of the 4 real stack pointer registers.

These are the combinations that exist:
sp -> msp -> msp_s
sp -> msp -> msp_ns
sp -> psp -> psp_s
sp -> psp -> psp_ns

This means that when the GDB client is to show the value of "msp",
the value should always be equal to either "msp_s" or "msp_ns".
Same goes for "psp".

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29121

Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
Signed-off-by: Yvan Roux <yvan.roux@foss.st.com>
---
 gdb/arm-tdep.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 1df57f5b5c8..e497dd1b3b8 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -288,6 +288,8 @@ struct arm_prologue_cache
 
   /* Active stack pointer.  */
   int active_sp_regnum;
+  int active_msp_regnum;
+  int active_psp_regnum;
 
   /* The frame base for this frame is just prev_sp - frame size.
      FRAMESIZE is the distance from the frame pointer to the
@@ -345,11 +347,23 @@ arm_cache_init (struct arm_prologue_cache *cache, struct frame_info *frame)
 
   if (tdep->have_sec_ext)
     {
+      CORE_ADDR msp_val = get_frame_register_unsigned (frame, tdep->m_profile_msp_regnum);
+      CORE_ADDR psp_val = get_frame_register_unsigned (frame, tdep->m_profile_psp_regnum);
+
       arm_cache_init_sp (tdep->m_profile_msp_s_regnum, &cache->msp_s, cache, frame);
       arm_cache_init_sp (tdep->m_profile_psp_s_regnum, &cache->psp_s, cache, frame);
       arm_cache_init_sp (tdep->m_profile_msp_ns_regnum, &cache->msp_ns, cache, frame);
       arm_cache_init_sp (tdep->m_profile_psp_ns_regnum, &cache->psp_ns, cache, frame);
 
+      if (msp_val == cache->msp_s)
+	cache->active_msp_regnum = tdep->m_profile_msp_s_regnum;
+      else if (msp_val == cache->msp_ns)
+	cache->active_msp_regnum = tdep->m_profile_msp_ns_regnum;
+      if (psp_val == cache->psp_s)
+	cache->active_psp_regnum = tdep->m_profile_psp_s_regnum;
+      else if (psp_val == cache->psp_ns)
+	cache->active_psp_regnum = tdep->m_profile_psp_ns_regnum;
+
       /* Use MSP_S as default stack pointer.  */
       if (cache->active_sp_regnum == ARM_SP_REGNUM)
 	  cache->active_sp_regnum = tdep->m_profile_msp_s_regnum;
@@ -384,6 +398,10 @@ arm_cache_get_sp_register (struct arm_prologue_cache *cache,
 	return cache->psp_s;
       if (regnum == tdep->m_profile_psp_ns_regnum)
 	return cache->psp_ns;
+      if (regnum == tdep->m_profile_msp_regnum)
+	return arm_cache_get_sp_register (cache, tdep, cache->active_msp_regnum);
+      if (regnum == tdep->m_profile_psp_regnum)
+	return arm_cache_get_sp_register (cache, tdep, cache->active_psp_regnum);
     }
   else if (tdep->is_m)
     {
-- 
2.17.1