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Commit c3412dcb authored by Will Schmidt's avatar Will Schmidt Committed by Paul Mackerras
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[POWERPC] Emulate power5 popcntb instruction 



In an attempt to make it easier for a power5 optimized app to run on a
power4 or a 970 or random earlier machine, this provides emulation of
the popcntb instruction.

Signed-off-by: default avatarWill Schmidt <will_schmidt@vnet.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent f50d4cfc

arch/powerpc/kernel/traps.c

+25 −0
Original line number Diff line number Diff line
@@ -598,6 +598,9 @@ static void parse_fpe(struct pt_regs *regs) 
#define INST_STSWI		0x7c0005aa

#define INST_STSWX		0x7c00052a



#define INST_POPCNTB		0x7c0000f4

#define INST_POPCNTB_MASK	0xfc0007fe



static int emulate_string_inst(struct pt_regs *regs, u32 instword)

{

	u8 rT = (instword >> 21) & 0x1f;
@@ -666,6 +669,23 @@ static int emulate_string_inst(struct pt_regs *regs, u32 instword) 
	return 0;

}



static int emulate_popcntb_inst(struct pt_regs *regs, u32 instword)

{

	u32 ra,rs;

	unsigned long tmp;



	ra = (instword >> 16) & 0x1f;

	rs = (instword >> 21) & 0x1f;



	tmp = regs->gpr[rs];

	tmp = tmp - ((tmp >> 1) & 0x5555555555555555ULL);

	tmp = (tmp & 0x3333333333333333ULL) + ((tmp >> 2) & 0x3333333333333333ULL);

	tmp = (tmp + (tmp >> 4)) & 0x0f0f0f0f0f0f0f0fULL;

	regs->gpr[ra] = tmp;



	return 0;

}



static int emulate_instruction(struct pt_regs *regs)

{

	u32 instword;
@@ -703,6 +723,11 @@ static int emulate_instruction(struct pt_regs *regs) 
	if ((instword & INST_STRING_GEN_MASK) == INST_STRING)

		return emulate_string_inst(regs, instword);



	/* Emulate the popcntb (Population Count Bytes) instruction. */

	if ((instword & INST_POPCNTB_MASK) == INST_POPCNTB) {

		return emulate_popcntb_inst(regs, instword);

	}



	return -EINVAL;

}