[PATCH 2/5] powerpc/lib/sstep: Add popcnt instruction emulation
From: Matt Brown <hidden>
Date: 2017-07-13 03:26:10
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
This adds emulations for the popcntb, popcntw, and popcntd instructions. Signed-off-by: Matt Brown <redacted> --- arch/powerpc/lib/sstep.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+)
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index f3e9ba8..cf69987 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c@@ -613,6 +613,30 @@ static nokprobe_inline void do_cmpb(struct pt_regs *regs, unsigned long v1, regs->gpr[rd] = out_val; } +/* + * The size parameter is used to ajust 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 int out_val, mask, n; + int i, j; + + out_val = 0; + + for (i = 0; i < (64 / size); i++) { + n = 0; + for (j = 0; j < size; j++) { + mask = 1 << (j + (i * size)); + if (v1 & mask) + n++; + } + out_val |= n << (i * size); + } + regs->gpr[ra] = out_val; +} + static nokprobe_inline int trap_compare(long v1, long v2) { int ret = 0;
@@ -1234,6 +1258,21 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs, regs->gpr[ra] = (signed int) regs->gpr[rd]; goto logical_done; #endif + case 299528: /* popcntb */ + val = regs->gpr[rd]; + do_popcnt(regs, val, 8, ra); + goto logical_done; + + case 17076744: /* popcntw */ + val = regs->gpr[rd]; + do_popcnt(regs, val, 32, ra); + goto logical_done; +#ifdef __powerpc64__ + case 19173896: /* popcntd */ + val = regs->gpr[rd]; + do_popcnt(regs, val, 64, ra); + goto logical_done; +#endif /* * Shift instructions
--
2.9.3