binutils/readelf: decode AMDGPU-specific e_flags

Decode and print the AMDGPU-specific fields of e_flags, as documented
here:

  https://llvm.org/docs/AMDGPUUsage.html#header

That is:

 - The specific GPU model
 - Whether the xnack and sramecc features are enabled

The result looks like:

-  Flags:                             0x52f
+  Flags:                             0x52f, gfx906, xnack any, sramecc any

The flags for the "HSA" OS ABI are properly versioned and documented on
that page.  But the NONE, PAL and MESA3D OS ABIs are not well documented
nor versioned.  Taking a peek at the LLVM source code, we see that they
encode their flags the same way as HSA v3.  For example, for PAL:

  https://github.com/llvm/llvm-project/blob/c8b614cd74a92d85936aed5ac7c642af75ffdc29/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp#L601

So for those other OS ABIs, we read them the same as HSA v3.

binutils/ChangeLog:

	* readelf.c: Include elf/amdgcn.h.
	(decode_AMDGPU_machine_flags): New.
	(get_machine_flags): Handle flags for EM_AMDGPU machine type.

include/ChangeLog:

	* elf/amdgcn.h: Add EF_AMDGPU_MACH_AMDGCN_* and
	EF_AMDGPU_FEATURE_* defines.

Change-Id: Ib5b94df7cae0719a22cf4e4fd0629330e9485c12

2 files changed, 158 insertions, 0 deletions

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index 694ad49..3ed0b0a 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,5 +1,11 @@
 2022-03-16  Simon Marchi  <simon.marchi@efficios.com>
 
+	* readelf.c: Include elf/amdgcn.h.
+	(decode_AMDGPU_machine_flags): New.
+	(get_machine_flags): Handle flags for EM_AMDGPU machine type.
+
+2022-03-16  Simon Marchi  <simon.marchi@efficios.com>
+
 	* readelf.c (get_osabi_name): Handle EM_AMDGPU OS ABIs.
 
 2022-03-16  Nick Clifton  <nickc@redhat.com>
diff --git a/binutils/readelf.c b/binutils/readelf.c
index e8974aa..00b5e54 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -92,6 +92,7 @@
 
 #include "elf/aarch64.h"
 #include "elf/alpha.h"
+#include "elf/amdgpu.h"
 #include "elf/arc.h"
 #include "elf/arm.h"
 #include "elf/avr.h"
@@ -3565,6 +3566,153 @@ decode_NDS32_machine_flags (unsigned e_flags, char buf[], size_t size)
     r += snprintf (buf + r, size -r, ", L2C");
 }
 
+static void
+decode_AMDGPU_machine_flags (Filedata *filedata, unsigned int e_flags,
+			     char *buf)
+{
+  unsigned char *e_ident = filedata->file_header.e_ident;
+  unsigned char osabi = e_ident[EI_OSABI];
+  unsigned char abiversion = e_ident[EI_ABIVERSION];
+  unsigned int mach;
+
+  /* HSA OS ABI v2 used a different encoding, but we don't need to support it,
+     it has been deprecated for a while.
+
+     The PAL, MESA3D and NONE OS ABIs are not properly versioned, at the time
+     of writing, they use the same flags as HSA v3, so the code below uses that
+     assumption.  */
+  if (osabi == ELFOSABI_AMDGPU_HSA && abiversion < ELFABIVERSION_AMDGPU_HSA_V3)
+    return;
+
+  mach = e_flags & EF_AMDGPU_MACH;
+  switch (mach)
+    {
+#define AMDGPU_CASE(code, string) \
+  case code: strcat (buf, ", " string); break;
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX600, "gfx600")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX601, "gfx601")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX700, "gfx700")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX701, "gfx701")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX702, "gfx702")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX703, "gfx703")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX704, "gfx704")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX801, "gfx801")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX802, "gfx802")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX803, "gfx803")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX810, "gfx810")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX900, "gfx900")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX902, "gfx902")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX904, "gfx904")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX906, "gfx906")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX908, "gfx908")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX909, "gfx909")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX90C, "gfx90c")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1010, "gfx1010")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1011, "gfx1011")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1012, "gfx1012")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1030, "gfx1030")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1031, "gfx1031")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1032, "gfx1032")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1033, "gfx1033")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX602, "gfx602")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX705, "gfx705")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX805, "gfx805")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1035, "gfx1035")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1034, "gfx1034")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX90A, "gfx90a")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX940, "gfx940")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1013, "gfx1013")
+    AMDGPU_CASE (EF_AMDGPU_MACH_AMDGCN_GFX1036, "gfx1036")
+    default:
+      sprintf (buf, _(", <unknown AMDGPU GPU type: %#x>"), mach);
+      break;
+#undef AMDGPU_CASE
+    }
+
+  buf += strlen (buf);
+  e_flags &= ~EF_AMDGPU_MACH;
+
+  if ((osabi == ELFOSABI_AMDGPU_HSA
+       && abiversion == ELFABIVERSION_AMDGPU_HSA_V3)
+      || osabi != ELFOSABI_AMDGPU_HSA)
+    {
+      /* For HSA v3 and other OS ABIs.  */
+      if (e_flags & EF_AMDGPU_FEATURE_XNACK_V3)
+	{
+	  strcat (buf, ", xnack on");
+	  buf += strlen (buf);
+	  e_flags &= ~EF_AMDGPU_FEATURE_XNACK_V3;
+	}
+
+      if (e_flags & EF_AMDGPU_FEATURE_SRAMECC_V3)
+	{
+	  strcat (buf, ", sramecc on");
+	  buf += strlen (buf);
+	  e_flags &= ~EF_AMDGPU_FEATURE_SRAMECC_V3;
+	}
+    }
+  else
+    {
+      /* For HSA v4+.  */
+      int xnack, sramecc;
+
+      xnack = e_flags & EF_AMDGPU_FEATURE_XNACK_V4;
+      switch (xnack)
+	{
+	case EF_AMDGPU_FEATURE_XNACK_UNSUPPORTED_V4:
+	  break;
+
+	case EF_AMDGPU_FEATURE_XNACK_ANY_V4:
+	  strcat (buf, ", xnack any");
+	  break;
+
+	case EF_AMDGPU_FEATURE_XNACK_OFF_V4:
+	  strcat (buf, ", xnack off");
+	  break;
+
+	case EF_AMDGPU_FEATURE_XNACK_ON_V4:
+	  strcat (buf, ", xnack on");
+	  break;
+
+	default:
+	  sprintf (buf, _(", <unknown xnack value: %#x>"), xnack);
+	  break;
+	}
+
+      buf += strlen (buf);
+      e_flags &= ~EF_AMDGPU_FEATURE_XNACK_V4;
+
+      sramecc = e_flags & EF_AMDGPU_FEATURE_SRAMECC_V4;
+      switch (sramecc)
+	{
+	case EF_AMDGPU_FEATURE_SRAMECC_UNSUPPORTED_V4:
+	  break;
+
+	case EF_AMDGPU_FEATURE_SRAMECC_ANY_V4:
+	  strcat (buf, ", sramecc any");
+	  break;
+
+	case EF_AMDGPU_FEATURE_SRAMECC_OFF_V4:
+	  strcat (buf, ", sramecc off");
+	  break;
+
+	case EF_AMDGPU_FEATURE_SRAMECC_ON_V4:
+	  strcat (buf, ", sramecc on");
+	  break;
+
+	default:
+	  sprintf (buf, _(", <unknown sramecc value: %#x>"), sramecc);
+	  break;
+	}
+
+      buf += strlen (buf);
+      e_flags &= ~EF_AMDGPU_FEATURE_SRAMECC_V4;
+    }
+
+  if (e_flags != 0)
+    sprintf (buf, _(", unknown flags bits: %#x"), e_flags);
+}
+
 static char *
 get_machine_flags (Filedata * filedata, unsigned e_flags, unsigned e_machine)
 {
@@ -3717,6 +3865,10 @@ get_machine_flags (Filedata * filedata, unsigned e_flags, unsigned e_machine)
 	    }
 	  break;
 
+	case EM_AMDGPU:
+	  decode_AMDGPU_machine_flags (filedata, e_flags, buf);
+	  break;
+
 	case EM_CYGNUS_MEP:
 	  switch (e_flags & EF_MEP_CPU_MASK)
 	    {