Re: [PATCH v6 4/4] risc/purgatory: Add linker script

From: Conor Dooley <conor@kernel.org>
To: Ricardo Ribalda <ribalda@chromium.org>
Cc: Tom Rix <trix@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	llvm@lists.linux.dev, "H. Peter Anvin" <hpa@zytor.com>,
	linux-riscv@lists.infradead.org,
	Philipp Rudo <prudo@linux.vnet.ibm.com>,
	Baoquan He <bhe@redhat.com>,
	x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
	Dave Young <dyoung@redhat.com>, Albert Ou <aou@eecs.berkeley.edu>,
	Ross Zwisler <zwisler@google.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Steven Rostedt <rostedt@goodmis.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Philipp Rudo <prudo@redhat.com>,
	kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org, Palmer Dabbelt <palmer@dabbelt.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Simon Horman <horms@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v6 4/4] risc/purgatory: Add linker script
Date: Mon, 1 May 2023 18:40:56 +0100	[thread overview]
Message-ID: <20230501-cottage-overjoyed-1aeb9d72d309@spud> (raw)
In-Reply-To: <20230321-kexec_clang16-v6-4-a2255e81ab45@chromium.org>

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Hey Ricardo,

On Mon, May 01, 2023 at 02:38:22PM +0200, Ricardo Ribalda wrote:
> If PGO is enabled, the purgatory ends up with multiple .text sections.
> This is not supported by kexec and crashes the system.
> 
> Cc: stable@vger.kernel.org
> Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory")
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  arch/riscv/purgatory/Makefile | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
> index 5730797a6b40..cf3a44121a90 100644
> --- a/arch/riscv/purgatory/Makefile
> +++ b/arch/riscv/purgatory/Makefile
> @@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS
>  CFLAGS_string.o := -D__DISABLE_EXPORTS
>  CFLAGS_ctype.o := -D__DISABLE_EXPORTS
>  
> +# When profile optimization is enabled, llvm emits two different overlapping
> +# text sections, which is not supported by kexec. Remove profile optimization
> +# flags.
> +KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))

With the caveat of not being au fait with the workings of either PGO or
of purgatory, how come you modify KBUILD_CFLAGS here rather than the
purgatory specific PURGATORY_CFLAGS that are used later in the file?

Cheers,
Conor.

> +
>  # When linking purgatory.ro with -r unresolved symbols are not checked,
>  # also link a purgatory.chk binary without -r to check for unresolved symbols.
>  PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
> 
> -- 
> 2.40.1.495.gc816e09b53d-goog
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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