On Thu, Jan 04, 2018 at 06:43:31PM +0000, Marc Zyngier wrote: > The encoder for ADD/SUB (immediate) can only cope with 12bit > immediates, while there is an encoding for a 12bit immediate shifted > by 12 bits to the left. > > Let's fix this small oversight by allowing the LSL_12 bit to be set. > > Signed-off-by: Marc Zyngier <[email protected]> > --- > arch/arm64/kernel/insn.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c > index 59669d7d4383..20655537cdd1 100644 > --- a/arch/arm64/kernel/insn.c > +++ b/arch/arm64/kernel/insn.c > @@ -35,6 +35,7 @@ > > #define AARCH64_INSN_SF_BIT BIT(31) > #define AARCH64_INSN_N_BIT BIT(22) > +#define AARCH64_INSN_LSL_12 BIT(22) > > static int aarch64_insn_encoding_class[] = { > AARCH64_INSN_CLS_UNKNOWN, > @@ -903,9 +904,18 @@ u32 aarch64_insn_gen_add_sub_imm(enum > aarch64_insn_register dst, > return AARCH64_BREAK_FAULT; > } > > + /* We can't encode more than a 24bit value (12bit + 12bit shift) */ > + if (imm & ~(BIT(24) - 1)) > + goto out; > + > + /* If we have something in the top 12 bits... */ > if (imm & ~(SZ_4K - 1)) { > - pr_err("%s: invalid immediate encoding %d\n", __func__, imm); > - return AARCH64_BREAK_FAULT; > + /* ... and in the low 12 bits -> error */ > + if (imm & (SZ_4K - 1)) > + goto out; > + > + imm >>= 12; > + insn |= AARCH64_INSN_LSL_12; > } > > insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RD, insn, dst); > @@ -913,6 +923,10 @@ u32 aarch64_insn_gen_add_sub_imm(enum > aarch64_insn_register dst, > insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, src); > > return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_12, insn, imm); > + > +out: > + pr_err("%s: invalid immediate encoding %d\n", __func__, imm); > + return AARCH64_BREAK_FAULT; > } > > u32 aarch64_insn_gen_bitfield(enum aarch64_insn_register dst,
Reviewed-by: Christoffer Dall <[email protected]> _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
