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From: Borislav Petkov <bp@alien8.de>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>, X86 ML <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 03/19] x86/insn: Add an insn_decode() API
Date: Tue, 29 Dec 2020 21:06:54 +0100	[thread overview]
Message-ID: <20201229200654.GF29947@zn.tnic> (raw)
In-Reply-To: <20201228101510.49082d470ed328d81486ef04@kernel.org>

On Mon, Dec 28, 2020 at 10:15:10AM +0900, Masami Hiramatsu wrote:
> BTW, insn_decode() can return -EINVAL if !insn_complete(), is that OK?

It does with this change. Or are you asking whether it returning -EINVAL
in that case is ok?

I don't see why not - this way callers can differentiate where it failed
- at fetching bytes with -ENODATA or it wasn't decoded completely -
-EINVAL.

> I think tools clone code must not use INSN_MODE_KERN because the tools may
> not use kernel Kconfig.
> 
> Hmm, this may be better to make a different patch to introduce a NOSYNC tag
> for sync checker in the tools. Something like;

I'd actually prefer this:

diff --git a/tools/arch/x86/include/asm/insn.h b/tools/arch/x86/include/asm/insn.h
index f8772b371452..545320c67855 100644
--- a/tools/arch/x86/include/asm/insn.h
+++ b/tools/arch/x86/include/asm/insn.h
@@ -98,8 +98,6 @@ extern int insn_get_length(struct insn *insn);
 enum insn_mode {
        INSN_MODE_32,
        INSN_MODE_64,
-       /* Mode is determined by the current kernel build. */
-       INSN_MODE_KERN,
        INSN_NUM_MODES,
 };
 

so that when a tool does use INSN_MODE_KERN, it would fail building:

In file included from util/intel-pt-decoder/intel-pt-insn-decoder.c:15:
util/intel-pt-decoder/../../../arch/x86/lib/insn.c: In function ‘insn_decode’:
util/intel-pt-decoder/../../../arch/x86/lib/insn.c:751:11: error: ‘INSN_MODE_KERN’ undeclared (first use in this function); did you mean ‘INSN_MODE_64’?
  751 |  if (m == INSN_MODE_KERN)
      |           ^~~~~~~~~~~~~~
      |           INSN_MODE_64
util/intel-pt-decoder/../../../arch/x86/lib/insn.c:751:11: note: each undeclared identifier is reported only once for each function it appears in
  LD       arch/perf-in.o
util/intel-pt-decoder/intel-pt-insn-decoder.c: In function ‘intel_pt_get_insn’:
util/intel-pt-decoder/intel-pt-insn-decoder.c:163:37: error: ‘INSN_MODE_KERN’ undeclared (first use in this function); did you mean ‘INSN_MODE_64’?
  163 |  ret = insn_decode(&insn, buf, len, INSN_MODE_KERN);
      |                                     ^~~~~~~~~~~~~~
      |                                     INSN_MODE_64

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2020-12-29 20:10 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-23 17:42 [PATCH v1 00/19] " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 01/19] x86/insn: Rename insn_decode() to insn_decode_regs() Borislav Petkov
2020-12-28 17:16   ` Sean Christopherson
2020-12-29 19:36     ` Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 02/19] x86/insn: Add @buf_len param to insn_init() kernel-doc comment Borislav Petkov
2020-12-28  1:44   ` Masami Hiramatsu
2020-12-23 17:42 ` [PATCH v1 03/19] x86/insn: Add an insn_decode() API Borislav Petkov
2020-12-28  1:15   ` Masami Hiramatsu
2020-12-29 20:06     ` Borislav Petkov [this message]
2020-12-30  9:00       ` Masami Hiramatsu
2020-12-30  9:28         ` Borislav Petkov
2021-01-06  5:21           ` Masami Hiramatsu
2021-01-08 18:59             ` Borislav Petkov
2021-01-12 11:34               ` Masami Hiramatsu
2021-01-13 18:06                 ` Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 04/19] x86/insn-eval: Handle return values from the decoder Borislav Petkov
2020-12-28 18:51   ` Sean Christopherson
2020-12-28 19:06     ` Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 05/19] x86/boot/compressed/sev-es: Convert to insn_decode() Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 06/19] perf/x86/intel/ds: Check insn_get_length() retval Borislav Petkov
2021-01-04 13:19   ` Peter Zijlstra
2021-01-19 10:40     ` Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 07/19] perf/x86/intel/ds: Check return values of insn decoder functions Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 08/19] x86/alternative: Use insn_decode() Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 09/19] x86/mce: Convert to insn_decode() Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 10/19] x86/kprobes: " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 11/19] x86/sev-es: " Borislav Petkov
2020-12-25 10:50   ` kernel test robot
2020-12-25 12:33     ` Borislav Petkov
2020-12-28 19:15       ` Sean Christopherson
2021-01-21 16:58         ` Borislav Petkov
2021-01-21 22:35           ` Sean Christopherson
2020-12-23 17:42 ` [PATCH v1 12/19] x86/traps: " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 13/19] x86/uprobes: " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 14/19] x86/tools/insn_decoder_test: " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 15/19] tools/objtool: " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 16/19] x86/tools/insn_sanity: " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 17/19] tools/perf: " Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 18/19] x86/insn: Remove kernel_insn_init() Borislav Petkov
2020-12-23 17:42 ` [PATCH v1 19/19] x86/insn: Make insn_complete() static Borislav Petkov
2020-12-27 15:26 ` [PATCH v1 00/19] x86/insn: Add an insn_decode() API Tom Lendacky
2021-02-03 12:00   ` Borislav Petkov

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