Re: [PATCH v3 21/21] klp-build: Add arm64 syscall patching macro
Josh Poimboeuf <[email protected]>
| Newsgroups | org.kernel.vger.live-patching,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <rumkp7mj6x4jo3r4x3erzkcwqkssbf5n46fxvrgcan7u4n2fuk@pkleqal5rqgr> |
On Fri, May 15, 2026 at 02:44:39AM +0000, [email protected] wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [Medium] The arm64 __KLP_SYSCALL_DEFINEx macro omits the ALLOW_ERROR_INJECTION declaration, silently breaking BPF error injection for livepatched syscalls. > -- > > commit b4d1a9ea352f196a7fd3e7198fdade51440d08e5 > Author: Josh Poimboeuf <[email protected]> > > klp-build: Add arm64 syscall patching macro > > This commit adds arm64 support for KLP_SYSCALL_DEFINEx(). The commit > message states it is mirroring the arm64 __SYSCALL_DEFINEx() pattern from > arch/arm64/include/asm/syscall_wrapper.h. > > > diff --git a/include/linux/livepatch_helpers.h b/include/linux/livepatch_helpers.h > > index 99d68d0773fa8..4b647b83865f9 100644 > > --- a/include/linux/livepatch_helpers.h > > +++ b/include/linux/livepatch_helpers.h > > @@ -72,6 +72,25 @@ > > } \ > > static inline long __klp_do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) > > > > +#elif defined(CONFIG_ARM64) > > + > > +#define __KLP_SYSCALL_DEFINEx(x, name, ...) \ > > + static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ > > + static inline long __klp_do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ > > + asmlinkage long __arm64_sys##name(const struct pt_regs *regs); \ > > + asmlinkage long __arm64_sys##name(const struct pt_regs *regs) \ > > + { \ > > + return __se_sys##name(SC_ARM64_REGS_TO_ARGS(x,__VA_ARGS__));\ > > + } \ > > Does this macro definition omit the ALLOW_ERROR_INJECTION declaration? > > The standard arm64 __SYSCALL_DEFINEx() macro explicitly registers the top-level > syscall handler with ALLOW_ERROR_INJECTION() to enable BPF error injection > workflows like bpf_override_return(). The x86 implementation correctly > preserves this functionality. > > Because this macro is missing that declaration, it looks like it might > introduce a regression where BPF cannot inject errors into the replacement > syscalls in a livepatch module on arm64. Fixed. -- Josh