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: Matt Brown <matthew.brown....@gmail.com> --- v2: - fixed opcodes - fixed typecasting - fixed bitshifting error for both 32 and 64bit arch --- arch/powerpc/lib/sstep.c | 43 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index 87d277f..e6a16a3 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -612,6 +612,35 @@ 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 high, low, mask; + unsigned int n; + int i, j; + + high = 0; + low = 0; + + for (i = 0; i < (64 / size); i++) { + n = 0; + for (j = 0; j < size; j++) { + mask = 1UL << (j + (i * size)); + if (v1 & mask) + n++; + } + if ((i * size) < 32) + low |= n << (i * size); + else + high |= n << ((i * size) - 32); + } + regs->gpr[ra] = (high << 32) | low; +} + static nokprobe_inline int trap_compare(long v1, long v2) { int ret = 0; @@ -1194,6 +1223,10 @@ 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; @@ -1206,6 +1239,10 @@ 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; @@ -1217,7 +1254,11 @@ 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 __powerpc64__ + 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; -- 2.9.3