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Commit c71b7eff authored by Anton Blanchard's avatar Anton Blanchard
Browse files

powerpc: Add ABIv2 support to ppc_function_entry 



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

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
parent 814e4cd9

arch/powerpc/include/asm/code-patching.h

+36 −4
Original line number Diff line number Diff line
@@ -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;



	/*

	 * 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.

	 * 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 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