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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "peterz@infradead.org" <peterz@infradead.org>,
	"chenzhongjin@huawei.com" <chenzhongjin@huawei.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"rostedt@goodmis.org" <rostedt@goodmis.org>,
	"aik@ozlabs.ru" <aik@ozlabs.ru>,
	"mingo@redhat.com" <mingo@redhat.com>,
	Sathvika Vasireddy <sv@linux.ibm.com>,
	"npiggin@gmail.com" <npiggin@gmail.com>,
	"jpoimboe@redhat.com" <jpoimboe@redhat.com>,
	"naveen.n.rao@linux.vnet.ibm.com"
	<naveen.n.rao@linux.vnet.ibm.com>,
	"mbenes@suse.cz" <mbenes@suse.cz>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v2 16/16] objtool/powerpc: Add --mcount specific implementation
Date: Wed, 31 Aug 2022 12:51:00 -0500	[thread overview]
Message-ID: <20220831175100.GS25951@gate.crashing.org> (raw)
In-Reply-To: <5da86617-53f1-d899-336a-53fe691e76ae@csgroup.eu>

On Wed, Aug 31, 2022 at 12:50:07PM +0000, Christophe Leroy wrote:
> Le 29/08/2022 à 07:52, Sathvika Vasireddy a écrit :
> > +	opcode = insn >> 26;
> > +
> > +	switch (opcode) {
> > +	case 18: /* bl */
> 
> case 18 is more than 'bl', it includes also 'b'.
> In both cases, the calculation of *immediate is the same.

It also is "ba" and "bla", sometimes written as "b[l][a]".

> It would therefore be more correct to perform the calculation and setup 
> of *immediate outside the 'if ((insn & 3) == 1)', that would avoid 
> unnecessary churn the day we add support for branches without link.
> 
> > +		if ((insn & 3) == 1) {
> > +			*type = INSN_CALL;
> > +			*immediate = insn & 0x3fffffc;
> > +			if (*immediate & 0x2000000)
> > +				*immediate -= 0x4000000;
> > +		}
> > +		break;
> > +	}

Does this handle AA=1 correctly at all?  That is valid both with and
without relocations, just like AA=0.  Same for AA=1 LK=0 btw.

If you only handle AA=0, the code should explicitly test for that.


Segher

  reply	other threads:[~2022-08-31 17:55 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-29  5:52 [PATCH v2 00/16] objtool: Enable and implement --mcount option on powerpc Sathvika Vasireddy
2022-08-29  5:52 ` [PATCH v2 01/16] powerpc: Replace unreachable() with it's builtin variant in __WARN_FLAGS() Sathvika Vasireddy
2022-08-30  6:15   ` Christophe Leroy
2022-09-05 10:18     ` Naveen N. Rao
2022-08-29  5:52 ` [PATCH v2 02/16] powerpc: override __ALIGN() and __ALIGN_STR() macros Sathvika Vasireddy
2022-08-29 13:26   ` Christophe Leroy
2022-08-29 14:39     ` Sathvika Vasireddy
2022-08-31  3:24   ` Nicholas Piggin
2022-08-31  7:22     ` Michael Ellerman
2022-09-05 11:03   ` Peter Zijlstra
2022-08-29  5:52 ` [PATCH v2 03/16] powerpc: Fix objtool unannotated intra-function call warnings Sathvika Vasireddy
2022-08-30  6:16   ` Christophe Leroy
2022-08-30 12:42   ` Christophe Leroy
2022-09-05 11:02   ` Peter Zijlstra
2022-08-29  5:52 ` [PATCH v2 04/16] powerpc: Curb objtool unannotated intra-function warnings Sathvika Vasireddy
2022-08-30  6:26   ` Christophe Leroy
2022-08-29  5:52 ` [PATCH v2 05/16] powerpc: Skip objtool from running on drivers/crypto/vmx/aesp8-ppc.o Sathvika Vasireddy
2022-08-30  6:26   ` Christophe Leroy
2022-09-01 19:17   ` Peter Zijlstra
2022-09-05 10:47     ` Naveen N. Rao
2022-08-29  5:52 ` [PATCH v2 06/16] powerpc: Fix objtool unannotated intra-function call warnings on PPC32 Sathvika Vasireddy
2022-08-29  5:52 ` [PATCH v2 07/16] powerpc: Skip objtool from running on VDSO files Sathvika Vasireddy
2022-08-30  6:27   ` Christophe Leroy
2022-09-01 19:19   ` Peter Zijlstra
2022-09-02  7:40     ` Michael Ellerman
2022-08-29  5:52 ` [PATCH v2 08/16] objtool: Fix SEGFAULT Sathvika Vasireddy
2022-09-01 19:20   ` Peter Zijlstra
2022-09-02  8:06     ` Christophe Leroy
2022-09-02  8:42       ` Peter Zijlstra
2022-08-29  5:52 ` [PATCH v2 09/16] objtool: Use target file endianness instead of a compiled constant Sathvika Vasireddy
2022-09-01 19:22   ` Peter Zijlstra
2022-08-29  5:52 ` [PATCH v2 10/16] objtool: Use target file class size " Sathvika Vasireddy
2022-09-01 19:23   ` Peter Zijlstra
2022-08-29  5:52 ` [PATCH v2 11/16] objtool: Add --mnop as an option to --mcount Sathvika Vasireddy
2022-08-30  6:28   ` Christophe Leroy
2022-09-01 19:25   ` Peter Zijlstra
2022-09-05 10:55     ` Naveen N. Rao
2022-08-29  5:52 ` [PATCH v2 12/16] objtool: Read special sections with alts only when specific options are selected Sathvika Vasireddy
2022-08-30  6:31   ` Christophe Leroy
2022-08-29  5:52 ` [PATCH v2 13/16] objtool: Use macros to define arch specific reloc types Sathvika Vasireddy
2022-08-30  6:33   ` Christophe Leroy
2022-09-01 19:28   ` Peter Zijlstra
2022-08-29  5:52 ` [PATCH v2 14/16] objtool: Add arch specific function arch_ftrace_match() Sathvika Vasireddy
2022-08-30  6:36   ` Christophe Leroy
2022-08-29  5:52 ` [PATCH v2 15/16] objtool/powerpc: Enable objtool to be built on ppc Sathvika Vasireddy
2022-08-30  6:41   ` Christophe Leroy
2022-09-05 10:37     ` Naveen N. Rao
2023-02-04  8:19     ` Randy Dunlap
2023-02-04  8:21       ` Randy Dunlap
2023-02-04  8:30         ` Randy Dunlap
2023-02-04 11:55           ` Christophe Leroy
2023-02-04 13:10             ` Christophe Leroy
2023-02-04 15:47               ` Josh Poimboeuf
2022-09-01  9:32   ` Christophe Leroy
2022-09-01 15:11     ` Segher Boessenkool
2022-09-01 16:38       ` Christophe Leroy
2022-09-01 19:01         ` Peter Zijlstra
2022-08-29  5:52 ` [PATCH v2 16/16] objtool/powerpc: Add --mcount specific implementation Sathvika Vasireddy
2022-08-30  6:44   ` Christophe Leroy
2022-08-31 12:50   ` Christophe Leroy
2022-08-31 17:51     ` Segher Boessenkool [this message]
2022-09-05 10:45       ` Naveen N. Rao
2022-09-05 20:43         ` Segher Boessenkool
2022-09-06  6:22           ` Christophe Leroy

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