[Qemu-devel] [PATCH] tcg-ppc64: Support the ELFv2 ABI

[Ulrich Weigand]

The new ELFv2 ABI, used by default on powerpc64le-linux hosts,
introduced some changes that are incompatible with code currently
generated by the ppc64 TGC target.  In particular, we no longer
use function descriptors.

This patch adds support for the ELFv2 ABI in the ppc64 TGC
function call and function prologue sequences.

Signed-off-by: Ulrich Weigand <address@hidden>
---
 tcg/ppc64/tcg-target.c |   18 +++++++++++++++++-
 1 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/tcg/ppc64/tcg-target.c b/tcg/ppc64/tcg-target.c
index 06e440f..4ef4838 100644
--- a/tcg/ppc64/tcg-target.c
+++ b/tcg/ppc64/tcg-target.c
@@ -717,6 +717,22 @@ static void tcg_out_call(TCGContext *s, tcg_target_long 
arg, int const_arg)
         tcg_out32(s, MTSPR | RS(arg) | LR);
         tcg_out32(s, BCLR | BO_ALWAYS | LK);
     }
+#elif _CALL_ELF == 2
+    /* In the ELFv2 ABI, we do not need to set up the TOC pointer in r2,
+       but instead we have to set up r12 to contain the destination address
+       when performing an indirect call.  */
+    TCGReg reg = arg;
+    if (const_arg) {
+        /* FIXME: we could use bl if we knew that the destination uses
+           the same TOC, and what its local entry point offset is.
+           For now, always perform an indirect call.  */
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R12, arg);
+        reg = TCG_REG_R12;
+    } else {
+        tcg_out_mov(s, TCG_TYPE_PTR, TCG_REG_R12, arg);
+    }
+    tcg_out32(s, MTSPR | RS(reg) | CTR);
+    tcg_out32(s, BCCTR | BO_ALWAYS | LK);
 #else
     TCGReg reg = arg;
     int ofs = 0;
@@ -1112,7 +1128,7 @@ static void tcg_target_qemu_prologue(TCGContext *s)
                   REG_SAVE_BOT - CPU_TEMP_BUF_NLONGS * sizeof(long),
                   CPU_TEMP_BUF_NLONGS * sizeof(long));
 
-#ifndef __APPLE__
+#if !defined(__APPLE__) && _CALL_ELF != 2
     /* First emit adhoc function descriptor */
     tcg_out64(s, (uint64_t)s->code_ptr + 24); /* entry point */
     s->code_ptr += 16;          /* skip TOC and environment pointer */
-- 
1.7.1

-- 
  Dr. Ulrich Weigand
  GNU/Linux compilers and toolchain
  address@hidden