libunwindstack: support for Armv8.3-A Pointer Authentication

This patch adds support for handling return addresses signed with
pointer authentication. It simply strips the authentication code
without verifying its correctness, and thus works with both A and B
keys and through key-change boundaries.

Additons:
  * DW_CFA_AARCH64_negate_ra_state: new CFA operation.
  * RA_SIGN_STATE: new pseudo register.
  * Pass the arch to DwarfCfa so that the new op is only executed
    on aarch64.

The stripping uses the xpaclri instruction. This is a hint space
instruction which is compatible with pre Armv8.3-A devices. For cases
where it cannot be used, a mask can be set instead.

Test: libunwindstack_test
      Without this patch all UnwindTest.* testcases should fail if
      compiled with Pointer Authentication.

The tests should be executed with both -mbranch-protection=pac-ret and
pac-ret+leaf flags so that either some or all functions have pointer
authentication instructions.

Change-Id: Id7c3f1d0e2fc7fccb19bd1430826264405a9df7c

1 files changed, 7 insertions, 4 deletions

diff --git a/libunwindstack/include/unwindstack/DwarfSection.h b/libunwindstack/include/unwindstack/DwarfSection.h
index c244749..af823da 100644
--- a/libunwindstack/include/unwindstack/DwarfSection.h
+++ b/libunwindstack/include/unwindstack/DwarfSection.h
@@ -31,6 +31,7 @@
 namespace unwindstack {
 
 // Forward declarations.
+enum ArchEnum : uint8_t;
 class Memory;
 class Regs;
 template <typename AddressType>
@@ -90,13 +91,14 @@ class DwarfSection {
 
   virtual bool Eval(const DwarfCie*, Memory*, const dwarf_loc_regs_t&, Regs*, bool*) = 0;
 
-  virtual bool Log(uint8_t indent, uint64_t pc, const DwarfFde* fde) = 0;
+  virtual bool Log(uint8_t indent, uint64_t pc, const DwarfFde* fde, ArchEnum arch) = 0;
 
   virtual void GetFdes(std::vector<const DwarfFde*>* fdes) = 0;
 
   virtual const DwarfFde* GetFdeFromPc(uint64_t pc) = 0;
 
-  virtual bool GetCfaLocationInfo(uint64_t pc, const DwarfFde* fde, dwarf_loc_regs_t* loc_regs) = 0;
+  virtual bool GetCfaLocationInfo(uint64_t pc, const DwarfFde* fde, dwarf_loc_regs_t* loc_regs,
+                                  ArchEnum arch) = 0;
 
   virtual uint64_t GetCieOffsetFromFde32(uint32_t pointer) = 0;
 
@@ -140,9 +142,10 @@ class DwarfSectionImpl : public DwarfSection {
   bool Eval(const DwarfCie* cie, Memory* regular_memory, const dwarf_loc_regs_t& loc_regs,
             Regs* regs, bool* finished) override;
 
-  bool GetCfaLocationInfo(uint64_t pc, const DwarfFde* fde, dwarf_loc_regs_t* loc_regs) override;
+  bool GetCfaLocationInfo(uint64_t pc, const DwarfFde* fde, dwarf_loc_regs_t* loc_regs,
+                          ArchEnum arch) override;
 
-  bool Log(uint8_t indent, uint64_t pc, const DwarfFde* fde) override;
+  bool Log(uint8_t indent, uint64_t pc, const DwarfFde* fde, ArchEnum arch) override;
 
  protected:
   bool GetNextCieOrFde(const DwarfFde** fde_entry);