Re: [PATCH v7 2/7] arm64: Add more test functions to insn.c

[Steve Capper]

Hi David,
Some comments below.

On 15 June 2015 at 20:07, David Long <dave.long@xxxxxxxxxx> wrote:
> From: "David A. Long" <dave.long@xxxxxxxxxx>
>
> Certain instructions are hard to execute correctly out-of-line (as in
> kprobes).  Test functions are added to insn.[hc] to identify these.  The
> instructions include any that use PC-relative addressing, change the PC,
> or change interrupt masking. For efficiency and simplicity test
> functions are also added for small collections of related instructions.
>
> Signed-off-by: David A. Long <dave.long@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/insn.h | 18 ++++++++++++++++++
>  arch/arm64/kernel/insn.c      | 28 ++++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+)
>
> diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
> index f81b328..1fdd237 100644
> --- a/arch/arm64/include/asm/insn.h
> +++ b/arch/arm64/include/asm/insn.h
> @@ -223,8 +223,13 @@ static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
>  static __always_inline u32 aarch64_insn_get_##abbr##_value(void) \
>  { return (val); }
>
> +__AARCH64_INSN_FUNCS(adr_adrp, 0x1F000000, 0x10000000)
> +__AARCH64_INSN_FUNCS(prfm_lit, 0xFF000000, 0xD8000000)
>  __AARCH64_INSN_FUNCS(str_reg,  0x3FE0EC00, 0x38206800)
>  __AARCH64_INSN_FUNCS(ldr_reg,  0x3FE0EC00, 0x38606800)
> +__AARCH64_INSN_FUNCS(ldr_lit,  0xBF000000, 0x18000000)
> +__AARCH64_INSN_FUNCS(ldrsw_lit,        0xFF000000, 0x98000000)
> +__AARCH64_INSN_FUNCS(exclusive,        0x3F000000, 0x08000000)

Going one step back, if we're worried about the exclusive monitors
then we'll be worried about instructions in-between the monitor pairs
too?


>  __AARCH64_INSN_FUNCS(stp_post, 0x7FC00000, 0x28800000)
>  __AARCH64_INSN_FUNCS(ldp_post, 0x7FC00000, 0x28C00000)
>  __AARCH64_INSN_FUNCS(stp_pre,  0x7FC00000, 0x29800000)
> @@ -264,19 +269,29 @@ __AARCH64_INSN_FUNCS(ands,        0x7F200000, 0x6A000000)
>  __AARCH64_INSN_FUNCS(bics,     0x7F200000, 0x6A200000)
>  __AARCH64_INSN_FUNCS(b,                0xFC000000, 0x14000000)
>  __AARCH64_INSN_FUNCS(bl,       0xFC000000, 0x94000000)
> +__AARCH64_INSN_FUNCS(b_bl,     0x7C000000, 0x14000000)
> +__AARCH64_INSN_FUNCS(cb,       0x7E000000, 0x34000000)
>  __AARCH64_INSN_FUNCS(cbz,      0x7F000000, 0x34000000)
>  __AARCH64_INSN_FUNCS(cbnz,     0x7F000000, 0x35000000)
> +__AARCH64_INSN_FUNCS(tb,       0x7E000000, 0x36000000)
>  __AARCH64_INSN_FUNCS(tbz,      0x7F000000, 0x36000000)
>  __AARCH64_INSN_FUNCS(tbnz,     0x7F000000, 0x37000000)
> +__AARCH64_INSN_FUNCS(b_bl_cb_tb, 0x5C000000, 0x14000000)
>  __AARCH64_INSN_FUNCS(bcond,    0xFF000010, 0x54000000)
>  __AARCH64_INSN_FUNCS(svc,      0xFFE0001F, 0xD4000001)
>  __AARCH64_INSN_FUNCS(hvc,      0xFFE0001F, 0xD4000002)
>  __AARCH64_INSN_FUNCS(smc,      0xFFE0001F, 0xD4000003)
>  __AARCH64_INSN_FUNCS(brk,      0xFFE0001F, 0xD4200000)
> +__AARCH64_INSN_FUNCS(exception,        0xFF000000, 0xD4000000)
>  __AARCH64_INSN_FUNCS(hint,     0xFFFFF01F, 0xD503201F)
>  __AARCH64_INSN_FUNCS(br,       0xFFFFFC1F, 0xD61F0000)
>  __AARCH64_INSN_FUNCS(blr,      0xFFFFFC1F, 0xD63F0000)
> +__AARCH64_INSN_FUNCS(br_blr,   0xFFDFFC1F, 0xD61F0000)
>  __AARCH64_INSN_FUNCS(ret,      0xFFFFFC1F, 0xD65F0000)
> +__AARCH64_INSN_FUNCS(msr_imm,  0xFFF8F000, 0xD5004000)

Should this not be:
__AARCH64_INSN_FUNCS(msr_imm,  0xFFF8F01F, 0xD500401F)
As the lower 5 bits of an MSR (immediate) are all 1?

> +__AARCH64_INSN_FUNCS(msr_reg,  0xFFF00000, 0xD5100000)
> +__AARCH64_INSN_FUNCS(set_clr_daif, 0xFFFFF0DF, 0xD50340DF)

Looks good, just an MSR immediate with either DAIFSet or DAIFClr.

> +__AARCH64_INSN_FUNCS(rd_wr_daif, 0xFFDFFFE0, 0xD51B4220)

Looks good, either MRS or MSR (register) where systemreg = DAIF.

>
>  #undef __AARCH64_INSN_FUNCS
>
> @@ -285,6 +300,9 @@ bool aarch64_insn_is_nop(u32 insn);
>  int aarch64_insn_read(void *addr, u32 *insnp);
>  int aarch64_insn_write(void *addr, u32 insn);
>  enum aarch64_insn_encoding_class aarch64_get_insn_class(u32 insn);
> +bool aarch64_insn_uses_literal(u32 insn);
> +bool aarch64_insn_is_branch(u32 insn);
> +bool aarch64_insn_is_daif_access(u32 insn);
>  u64 aarch64_insn_decode_immediate(enum aarch64_insn_imm_type type, u32 insn);
>  u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
>                                   u32 insn, u64 imm);
> diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
> index 9249020..ecd8882 100644
> --- a/arch/arm64/kernel/insn.c
> +++ b/arch/arm64/kernel/insn.c
> @@ -155,6 +155,34 @@ static bool __kprobes __aarch64_insn_hotpatch_safe(u32 insn)
>                 aarch64_insn_is_nop(insn);
>  }
>
> +bool __kprobes aarch64_insn_uses_literal(u32 insn)
> +{
> +       /* ldr/ldrsw (literal), prfm */
> +
> +       return aarch64_insn_is_ldr_lit(insn) ||
> +               aarch64_insn_is_ldrsw_lit(insn) ||
> +               aarch64_insn_is_adr_adrp(insn) ||
> +               aarch64_insn_is_prfm_lit(insn);
> +}
> +
> +bool __kprobes aarch64_insn_is_branch(u32 insn)
> +{
> +       /* b, bl, cb*, tb*, b.cond, br, blr */
> +
> +       return aarch64_insn_is_b_bl_cb_tb(insn) ||
> +               aarch64_insn_is_br_blr(insn) ||
> +               aarch64_insn_is_ret(insn) ||
> +               aarch64_insn_is_bcond(insn);
> +}
> +
> +bool __kprobes aarch64_insn_is_daif_access(u32 insn)
> +{
> +       /* msr daif, mrs daif, msr daifset, msr daifclr */
> +
> +       return aarch64_insn_is_rd_wr_daif(insn) ||
> +               aarch64_insn_is_set_clr_daif(insn);
> +}
> +
>  /*
>   * ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a
>   * Section B2.6.5 "Concurrent modification and execution of instructions":
> --
> 1.8.1.2
>
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