powerpc: Add ABIv2 support to ppc_function_entry

Skip over the well known global entry point code for ABIv2.

Signed-off-by: Anton Blanchard <anton@samba.org>

1 files changed, 36 insertions, 4 deletions

diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index 97e02f985df8..37991e154ef8 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -42,15 +42,47 @@ void __patch_exception(int exc, unsigned long addr);
 } while (0)
 #endif
 
+#define OP_RT_RA_MASK   0xffff0000UL
+#define LIS_R2          0x3c020000UL
+#define ADDIS_R2_R12    0x3c4c0000UL
+#define ADDI_R2_R2      0x38420000UL
+
 static inline unsigned long ppc_function_entry(void *func)
 {
-#ifdef CONFIG_PPC64
+#if defined(CONFIG_PPC64)
+#if defined(_CALL_ELF) && _CALL_ELF == 2
+        u32 *insn = func;
+
+        /*
+         * A PPC64 ABIv2 function may have a local and a global entry
+         * point. We need to use the local entry point when patching
+         * functions, so identify and step over the global entry point
+         * sequence.
+         *
+         * The global entry point sequence is always of the form:
+         *
+         * addis r2,r12,XXXX
+         * addi  r2,r2,XXXX
+         *
+         * A linker optimisation may convert the addis to lis:
+         *
+         * lis   r2,XXXX
+         * addi  r2,r2,XXXX
+         */
+        if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
+             ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
+            ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
+                return (unsigned long)(insn + 2);
+        else
+                return (unsigned long)func;
+#else
         /*
-         * On PPC64 the function pointer actually points to the function's
-         * descriptor. The first entry in the descriptor is the address
-         * of the function text.
+         * On PPC64 ABIv1 the function pointer actually points to the
+         * function's descriptor. The first entry in the descriptor is the
+         * address of the function text.
          */
         return ((func_descr_t *)func)->entry;
+#endif
 #else
         return (unsigned long)func;
 #endif