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From: Hans de Goede <hdegoede@redhat.com>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols
Date: Thu, 12 Mar 2020 18:46:44 +0100	[thread overview]
Message-ID: <e96ea0cc-954d-2cd3-8d9d-53d57856d8aa@redhat.com> (raw)
In-Reply-To: <20200312001006.GA170175@rani.riverdale.lan>

Hi,

On 3/12/20 1:10 AM, Arvind Sankar wrote:
> On Wed, Mar 11, 2020 at 10:46:01PM +0100, Hans de Goede wrote:
>> Since we link purgatory.ro with -r aka we enable "incremental linking"
>> no checks for unresolved symbols is done while linking purgatory.ro.
>>
> 
> Do we actually need to link purgatory with -r? We could use
> --emit-relocs to get the relocation sections generated the way the main
> x86 kernel does, no?
> 
> Eg like the below? This would avoid the double-link creating
> purgatory.chk.

So I've changed the patch for this in my local tree over to the version
suggested below and tested kexec with this (and I can confirm that it
still works)

I'm wondering though if it would not be better to keep the purgatory.ro name ?  :

1. The generated ELF binary should still be relocatable
2. .ro files are part of the global .gitignore settings, for the
    new purgatory name we need to add an arch/x86/purgatory/.gitignore file
3. Keeping the purgatory.ro name will make the diff easier to read

Regards,

Hans


> 
> diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
> index fb4ee5444379..5332f95ca1d3 100644
> --- a/arch/x86/purgatory/Makefile
> +++ b/arch/x86/purgatory/Makefile
> @@ -14,8 +14,8 @@ $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
>   
>   CFLAGS_sha256.o := -D__DISABLE_EXPORTS
>   
> -LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib
> -targets += purgatory.ro
> +LDFLAGS_purgatory := -e purgatory_start --emit-relocs -nostdlib -z nodefaultlib
> +targets += purgatory
>   
>   KASAN_SANITIZE	:= n
>   KCOV_INSTRUMENT := n
> @@ -55,7 +55,7 @@ CFLAGS_sha256.o			+= $(PURGATORY_CFLAGS)
>   CFLAGS_REMOVE_string.o		+= $(PURGATORY_CFLAGS_REMOVE)
>   CFLAGS_string.o			+= $(PURGATORY_CFLAGS)
>   
> -$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
> +$(obj)/purgatory: $(PURGATORY_OBJS) FORCE
>   		$(call if_changed,ld)
>   
>   targets += kexec-purgatory.c
> @@ -63,7 +63,7 @@ targets += kexec-purgatory.c
>   quiet_cmd_bin2c = BIN2C   $@
>         cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@
>   
> -$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
> +$(obj)/kexec-purgatory.c: $(obj)/purgatory FORCE
>   	$(call if_changed,bin2c)
>   
>   obj-$(CONFIG_KEXEC_FILE)	+= kexec-purgatory.o
> 


  parent reply	other threads:[~2020-03-12 17:46 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 21:45 [PATCH v4 0/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols Hans de Goede
2020-03-11 21:46 ` [PATCH v4 1/2] x86/purgatory: Fix missing ftrace_likely_update symbol Hans de Goede
2020-03-11 21:46 ` [PATCH v4 2/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols Hans de Goede
2020-03-12  0:10   ` Arvind Sankar
2020-03-12 11:31     ` Hans de Goede
2020-03-12 11:42       ` Borislav Petkov
2020-03-12 11:58         ` Hans de Goede
2020-03-12 12:50           ` Borislav Petkov
2020-03-12 13:34             ` Hans de Goede
2020-03-12 14:25               ` Borislav Petkov
2020-03-12 14:38                 ` Hans de Goede
2020-03-12 14:49                   ` Borislav Petkov
2020-03-12 14:57                     ` Hans de Goede
2020-03-12 15:12                       ` Borislav Petkov
2020-03-13  4:42             ` Arvind Sankar
2020-03-13  4:58               ` Arvind Sankar
2020-03-13  5:15                 ` Arvind Sankar
2020-03-16 18:52                 ` Nick Desaulniers
2020-03-13 10:47               ` Hans de Goede
2020-03-13 18:06               ` Borislav Petkov
2020-03-12 17:46     ` Hans de Goede [this message]
2020-03-12 18:23       ` Arvind Sankar

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