2022-02-24 16:15:55

by Peter Zijlstra

Subject: [PATCH v2 03/39] x86/module: Fix the paravirt vs alternative order

Ever since commit 4e6292114c741 ("x86/paravirt: Add new features for
paravirt patching") there is an ordering dependency between patching
paravirt ops and patching alternatives, the module loader still
violates this.

Fixes: 4e6292114c741 ("x86/paravirt: Add new features for paravirt patching")
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
---
arch/x86/kernel/module.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -273,6 +273,14 @@ int module_finalize(const Elf_Ehdr *hdr,
retpolines = s;
}

+ /*
+ * See alternative_instructions() for the ordering rules between the
+ * various patching types.
+ */
+ if (para) {
+ void *pseg = (void *)para->sh_addr;
+ apply_paravirt(pseg, pseg + para->sh_size);
+ }
if (retpolines) {
void *rseg = (void *)retpolines->sh_addr;
apply_retpolines(rseg, rseg + retpolines->sh_size);
@@ -290,11 +298,6 @@ int module_finalize(const Elf_Ehdr *hdr,
tseg, tseg + text->sh_size);
}

- if (para) {
- void *pseg = (void *)para->sh_addr;
- apply_paravirt(pseg, pseg + para->sh_size);
- }
-
/* make jump label nops */
jump_label_apply_nops(me);

2022-03-01 23:13:23

by Miroslav Benes

Subject: Re: [PATCH v2 03/39] x86/module: Fix the paravirt vs alternative order

On Thu, 24 Feb 2022, Peter Zijlstra wrote:

> Ever since commit 4e6292114c741 ("x86/paravirt: Add new features for
> paravirt patching") there is an ordering dependency between patching
> paravirt ops and patching alternatives, the module loader still
> violates this.
>
> Fixes: 4e6292114c741 ("x86/paravirt: Add new features for paravirt patching")
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>

Reviewed-by: Miroslav Benes <[email protected]>

M