[RISCV] Add GNU note property and CFI support (#587)

* RISCV: add GNU property note support

Signed-off-by: Jerry Zhang Jian <jerry.zhangjian@sifive.com>

* RISCV: add Zicfiss and Zicfilp as GNU properties

Signed-off-by: Jerry Zhang Jian <jerry.zhangjian@sifive.com>

* RISCV: add support to describe gnu notes

Signed-off-by: Jerry Zhang Jian <jerry.zhangjian@sifive.com>

---------

Signed-off-by: Jerry Zhang Jian <jerry.zhangjian@sifive.com>

Author: jerryzj

elftools/elf/descriptions.py

@@ -320,6 +320,12 @@ def describe_note_gnu_properties(properties, machine):
                 prop_desc = ' <corrupt length: 0x%x>' % sz
             else:
                 prop_desc = describe_note_gnu_property_bitmap_and(_DESCR_NOTE_GNU_PROPERTY_AARCH64_FEATURE_1_AND, 'aarch64 feature', d)
+        elif t == 'GNU_PROPERTY_AARCH64_FEATURE_1_AND' and machine == 'EM_RISCV':
+            # RISC-V shares the same bit-mask with AArch64
+            if sz != 4:
+                prop_desc = ' <corrupt length: 0x%x>' % sz
+            else:
+                prop_desc = describe_note_gnu_property_bitmap_and(_DESCR_NOTE_GNU_PROPERTY_RISCV_FEATURE_1_AND, 'RISC-V AND feature', d)
         elif _DESCR_NOTE_GNU_PROPERTY_TYPE_LOPROC <= t <= _DESCR_NOTE_GNU_PROPERTY_TYPE_HIPROC:
             prop_desc = '<processor-specific type 0x%x data: %s >' % (t, bytes2hex(d, sep=' '))
         elif _DESCR_NOTE_GNU_PROPERTY_TYPE_LOUSER <= t <= _DESCR_NOTE_GNU_PROPERTY_TYPE_HIUSER:
@@ -675,6 +681,11 @@ def describe_note_gnu_properties(properties, machine):
     (2, 'pac'),
 )
 
+_DESCR_NOTE_GNU_PROPERTY_RISCV_FEATURE_1_AND = (
+    (1, 'ZICFILP'),
+    (2, 'ZICFISS'),
+)
+
 def _reverse_dict(d, low_priority=()):
     """
     This is a tiny helper function to "reverse" the keys/values of a dictionary

elftools/elf/structs.py

@@ -407,7 +407,9 @@ def classify_pr_data(ctx):
             if ctx.pr_type.startswith('GNU_PROPERTY_X86_'):
                 return ('GNU_PROPERTY_X86_*', 4, 0)
             elif ctx.pr_type.startswith('GNU_PROPERTY_AARCH64_'):
-                return ('GNU_PROPERTY_AARCH64_*', 4, 0)            
+                return ('GNU_PROPERTY_AARCH64_*', 4, 0)
+            elif ctx.pr_type.startswith('GNU_PROPERTY_RISCV_'):
+                return ('GNU_PROPERTY_RISCV_*', 4, 0)
             return (ctx.pr_type, ctx.pr_datasz, self.elfclass)
 
         self.Elf_Prop = Struct('Elf_Prop',
@@ -418,6 +420,7 @@ def classify_pr_data(ctx):
                     ('GNU_PROPERTY_STACK_SIZE', 8, 64): self.Elf_word64('pr_data'),
                     ('GNU_PROPERTY_X86_*', 4, 0): self.Elf_word('pr_data'),
                     ('GNU_PROPERTY_AARCH64_*', 4, 0): self.Elf_word('pr_data'),
+                    ('GNU_PROPERTY_RISCV_*', 4, 0): self.Elf_word('pr_data'),
                 },
                 default=Field('pr_data', lambda ctx: ctx.pr_datasz)
             ),