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Commit dcbd19b4 authored by Matt Brown's avatar Matt Brown Committed by Michael Ellerman
Browse files

powerpc/lib/sstep: Add popcnt instruction emulation 



This adds emulations for the popcntb, popcntw, and popcntd instructions.
Tested for correctness against the popcnt{b,w,d} instructions on ppc64le.

Signed-off-by: default avatarMatt Brown <matthew.brown.dev@gmail.com>
Reviewed-by: default avatarCyril Bur <cyrilbur@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 02c0f62a

arch/powerpc/lib/sstep.c

+41 −1
Original line number Diff line number Diff line
@@ -612,6 +612,34 @@ static nokprobe_inline void do_cmpb(struct pt_regs *regs, unsigned long v1, 
	regs->gpr[rd] = out_val;

}



/*

 * The size parameter is used to adjust the equivalent popcnt instruction.

 * popcntb = 8, popcntw = 32, popcntd = 64

 */

static nokprobe_inline void do_popcnt(struct pt_regs *regs, unsigned long v1,

				int size, int ra)

{

	unsigned long long out = v1;



	out -= (out >> 1) & 0x5555555555555555;

	out = (0x3333333333333333 & out) + (0x3333333333333333 & (out >> 2));

	out = (out + (out >> 4)) & 0x0f0f0f0f0f0f0f0f;



	if (size == 8) {	/* popcntb */

		regs->gpr[ra] = out;

		return;

	}

	out += out >> 8;

	out += out >> 16;

	if (size == 32) {	/* popcntw */

		regs->gpr[ra] = out & 0x0000003f0000003f;

		return;

	}



	out = (out + (out >> 32)) & 0x7f;

	regs->gpr[ra] = out;	/* popcntd */

}



static nokprobe_inline int trap_compare(long v1, long v2)

{

	int ret = 0;
@@ -1209,6 +1237,10 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs, 
			regs->gpr[ra] = regs->gpr[rd] & ~regs->gpr[rb];

			goto logical_done;



		case 122:	/* popcntb */

			do_popcnt(regs, regs->gpr[rd], 8, ra);

			goto logical_done;



		case 124:	/* nor */

			regs->gpr[ra] = ~(regs->gpr[rd] | regs->gpr[rb]);

			goto logical_done;
@@ -1221,6 +1253,10 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs, 
			regs->gpr[ra] = regs->gpr[rd] ^ regs->gpr[rb];

			goto logical_done;



		case 378:	/* popcntw */

			do_popcnt(regs, regs->gpr[rd], 32, ra);

			goto logical_done;



		case 412:	/* orc */

			regs->gpr[ra] = regs->gpr[rd] | ~regs->gpr[rb];

			goto logical_done;
@@ -1232,7 +1268,11 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs, 
		case 476:	/* nand */

			regs->gpr[ra] = ~(regs->gpr[rd] & regs->gpr[rb]);

			goto logical_done;



#ifdef CONFIG_PPC64

		case 506:	/* popcntd */

			do_popcnt(regs, regs->gpr[rd], 64, ra);

			goto logical_done;

#endif

		case 922:	/* extsh */

			regs->gpr[ra] = (signed short) regs->gpr[rd];

			goto logical_done;