Re: [PATCH LP-BUILD-TOOLS] Allow patching files compiled multiple times

[Ross Lagerwall <ross.lagerwall@citrix.com>]

On 02/23/2018 05:08 PM, Ross Lagerwall wrote:
> gas prior to binutils commit fbdf9406b0 (appears in 2.27) outputs symbol
> table entries resulting from .file in reverse order. If we get two
> consecutive file symbols, prefer the first one if that names an object
> file or has a directory component (to cover multiply compiled files).
> 
> This is the same workaround that was applied in Xen commit d37d63d4b548
> ("symbols: prefix static symbols with their source file names") for
> Xen's internal symbol table.
> 
> This fixes building a livepatch for XSA-243.
> ---
>   lookup.c | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
> 
> diff --git a/lookup.c b/lookup.c
> index 39125c6..645b91a 100644
> --- a/lookup.c
> +++ b/lookup.c
> @@ -149,16 +149,34 @@ int lookup_local_symbol(struct lookup_table *table, char *name, char *hint,
>   	struct symbol *sym, *match = NULL;
>   	int i;
>   	char *curfile = NULL;
> +	enum { other, multi_source } last_type = other;
>   
>   	memset(result, 0, sizeof(*result));
>   	for_each_symbol(i, sym, table) {
>   		if (sym->type == STT_FILE) {
> +			const char *ext = strrchr(sym->name, '.');
> +			int multi = strchr(sym->name, '/') ||
> +				    (ext && ext[1] == 'o');
> +
> +			/*
> +			 * gas prior to binutils commit fbdf9406b0 (appears in
> +			 * 2.27) outputs symbol table entries resulting from
> +			 * .file in reverse order. If we get two consecutive
> +			 * file symbols, prefer the first one if that names an
> +			 * object file or has a directory component (to cover
> +			 * multiply compiled files).
> +			 */
> +			if (last_type == multi_source)
> +				continue;
> +
>   			if (!strcmp(sym->name, hint)) {
>   				curfile = sym->name;
> +				last_type = multi ? multi_source : other;
>   				continue; /* begin hint file symbols */
>   			} else if (curfile)
>   				curfile = NULL; /* end hint file symbols */
>   		}
> +		last_type = other;
>   		if (!curfile)
>   			continue;
>   		if (sym->bind == STB_LOCAL && !strcmp(sym->name, name)) {
> 

Ping, Konrad?

-- 
Ross Lagerwall

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