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Re: [PATCH 3/3] livepatch: correctly handle altinstruction sections
- To: Roger Pau Monne <roger.pau@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Fri, 11 Mar 2022 08:35:18 +0100
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- Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>, doebel@xxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Fri, 11 Mar 2022 07:35:27 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 10.03.2022 16:08, Roger Pau Monne wrote:
> --- a/common.c
> +++ b/common.c
> @@ -249,19 +249,22 @@ int is_text_section(struct section *sec)
> (sec->sh.sh_flags & SHF_EXECINSTR));
> }
>
> +#define SEC_MATCH(n) !strncmp(sec->name, n, strlen(n) - 1)
> int is_rodata_section(struct section *sec)
> {
> return sec->sh.sh_type == SHT_PROGBITS &&
> !(sec->sh.sh_flags & (SHF_EXECINSTR | SHF_WRITE)) &&
> - !strncmp(sec->name, ".rodata", 7);
> + (SEC_MATCH(".rodata") || SEC_MATCH(".data.ro_after_init"));
> }
>
> int is_init_section(struct section *sec)
> {
> return sec->sh.sh_type == SHT_PROGBITS &&
> (sec->sh.sh_flags & SHF_ALLOC) &&
> - !strncmp(sec->name, ".init", 5);
> + (SEC_MATCH(".init") || SEC_MATCH(".text.startup") ||
> + SEC_MATCH(".altinstr") || SEC_MATCH(".ctors"));
Having dealt with this recently - what about .init_array? Modern gcc
prefers that over .ctors. Of course the question is whether either
really needs dealing with here - these sections, to my knowledge,
appear only with gcov support enabled. Not sure that's a case where
livepatching is actually expected to be used.
Jan
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