Re: [PATCH] x86/livepatch: Fail the build if duplicate symbols exist

From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
	"Wei Liu" <wei.liu2@citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>,
	"Ross Lagerwall" <ross.lagerwall@citrix.com>,
	"Julien Grall" <julien.grall@arm.com>,
	"Norbert Manthey" <nmanthey@amazon.de>,
	"Jan Beulich" <JBeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH] x86/livepatch: Fail the build if duplicate symbols exist
Date: Fri, 5 Apr 2019 17:02:50 -0400	[thread overview]
Message-ID: <20190405210250.GA18169@char.us.oracle.com> (raw)
In-Reply-To: <1554492364-21684-1-git-send-email-andrew.cooper3@citrix.com>

On Fri, Apr 05, 2019 at 08:26:04PM +0100, Andrew Cooper wrote:
> From: Ross Lagerwall <ross.lagerwall@citrix.com>
> 
> The binary diffing algorithm used by xen-livepatch depends on having unique
> symbols.
> 
> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>


> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> CC: Roger Pau Monné <roger.pau@citrix.com>
> CC: Stefano Stabellini <sstabellini@kernel.org>
> CC: Julien Grall <julien.grall@arm.com>
> CC: Ross Lagerwall <ross.lagerwall@citrix.com>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> CC: Norbert Manthey <nmanthey@amazon.de>
> 
> This patch has been part of the XenServer patchqueue for ages, and should have
> been upstreamed sooner.  It obviously can't be applied while the "block
> speculation" issue is outstanding.
> ---
>  xen/arch/x86/Makefile |  1 +
>  xen/tools/symbols.c   | 11 +++++++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
> index ef09939..d4ae46b 100644
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -98,6 +98,7 @@ endif
>  
>  syms-warn-dup-y := --warn-dup
>  syms-warn-dup-$(CONFIG_SUPPRESS_DUPLICATE_SYMBOL_WARNINGS) :=
> +syms-warn-dup-$(CONFIG_LIVEPATCH) := --error-dup
>  
>  $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
>  	./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TARGET) $(XEN_IMG_OFFSET) \
> diff --git a/xen/tools/symbols.c b/xen/tools/symbols.c
> index 05139d1..9f9e2c9 100644
> --- a/xen/tools/symbols.c
> +++ b/xen/tools/symbols.c
> @@ -599,7 +599,7 @@ static int compare_name(const void *p1, const void *p2)
>  int main(int argc, char **argv)
>  {
>  	unsigned int i;
> -	bool unsorted = false, warn_dup = false;
> +	bool unsorted = false, warn_dup = false, error_dup = false, found_dup = false;
>  
>  	if (argc >= 2) {
>  		for (i = 1; i < argc; i++) {
> @@ -619,6 +619,8 @@ int main(int argc, char **argv)
>  				sort_by_name = 1;
>  			else if (strcmp(argv[i], "--warn-dup") == 0)
>  				warn_dup = true;
> +			else if (strcmp(argv[i], "--error-dup") == 0)
> +				warn_dup = error_dup = true;
>  			else if (strcmp(argv[i], "--xensyms") == 0)
>  				map_only = true;
>  			else
> @@ -634,14 +636,19 @@ int main(int argc, char **argv)
>  		for (i = 1; i < table_cnt; ++i)
>  			if (strcmp(SYMBOL_NAME(table + i - 1),
>  				   SYMBOL_NAME(table + i)) == 0 &&
> -			    table[i - 1].addr != table[i].addr)
> +			    table[i - 1].addr != table[i].addr) {
>  				fprintf(stderr,
>  					"Duplicate symbol '%s' (%llx != %llx)\n",
>  					SYMBOL_NAME(table + i),
>  					table[i].addr, table[i - 1].addr);
> +				found_dup = true;
> +			}
>  		unsorted = true;
>  	}
>  
> +	if (error_dup && found_dup)
> +		exit(1);
> +
>  	if (unsorted)
>  		qsort(table, table_cnt, sizeof(*table), compare_value);
>  
> -- 
> 2.1.4
> 

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