Re: [PATCH v9 14/15] arm: Reorganize syscall table and separated the ABIs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential
issues to consider:
- [High] arm: missing oabic entry for sys_syscall() breaks OABI compat
  syscall(2)
- [Low] arm: Makefile overwrites gen-y with := and drops calls-oabi.S
  generation
--

commit f142c55483ada4ca8dfa9f75478b67abaeef8965
Author: André Almeida <andrealmeid@igalia.com>

arm: Reorganize syscall table and separated the ABIs

This commit separates the EABI, OABI, and OABI compat (oabic) ABIs in
arch/arm/tools/syscall.tbl, drops the compat column entries, and generates
calls-oabic.S for sys_oabi_call_table.

> diff --git a/arch/arm/tools/Makefile b/arch/arm/tools/Makefile
> index 28b6da8ac5f64..cde235b382bdc 100644
> --- a/arch/arm/tools/Makefile
> +++ b/arch/arm/tools/Makefile
> @@ -14,6 +14,7 @@ systbl := $(srctree)/scripts/syscalltbl.sh
>  syscall := $(src)/syscall.tbl
>  
>  gen-y := $(gen)/calls-oabi.S
> +gen-y := $(gen)/calls-oabic.S
>  gen-y += $(gen)/calls-eabi.S
>  kapi-hdrs-y := $(kapi)/unistd-nr.h
>  kapi-hdrs-y += $(kapi)/mach-types.h

[Severity: Low]
Should this assignment use += instead of := when adding calls-oabic.S to
gen-y?

Using := overwrites gen-y and drops $(gen)/calls-oabi.S from the kapi
prerequisites in arch/arm/tools/Makefile. When building with CONFIG_AEABI
disabled, sys_call_table in arch/arm/kernel/entry-common.S still includes
calls-oabi.S:

arch/arm/kernel/entry-common.S:
	syscall_table_start sys_call_table
#ifdef CONFIG_AEABI
#include <calls-eabi.S>
#else
#include <calls-oabi.S>
#endif
	syscall_table_end sys_call_table

which causes the build to fail because arch/arm/include/generated/calls-oabi.S
is no longer generated.

> diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
> index 55717ed32c27e..944f11030ab4a 100644
> --- a/arch/arm/tools/syscall.tbl
> +++ b/arch/arm/tools/syscall.tbl

[ ... ]

> @@ -131,7 +141,8 @@
>  114	common	wait4			sys_wait4
>  115	common	swapoff			sys_swapoff
>  116	common	sysinfo			sys_sysinfo
> -117	oabi	ipc			sys_ipc			sys_oabi_ipc
> +117	oabi	ipc			sys_ipc
> +117	oabic	ipc			sys_oabi_ipc

[Severity: High]
Just above syscall 114 in arch/arm/tools/syscall.tbl, syscall 113 is defined
only for oabi:

# syscall to call a syscall!
113	oabi	syscall			sys_syscall

Since sys_oabi_call_table in arch/arm/kernel/entry-common.S (compiled under
CONFIG_OABI_COMPAT) now includes calls-oabic.S instead of calls-oabi.S:

arch/arm/kernel/entry-common.S:
	syscall_table_start sys_oabi_call_table
#undef __SYSCALL_WITH_COMPAT
#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
#include <calls-oabic.S>
	syscall_table_end sys_oabi_call_table

won't omitting an oabic entry for syscall 113 cause scripts/syscalltbl.sh to
emit sys_ni_syscall for slot 113 in calls-oabic.S, breaking indirect syscalls
via syscall(2) for OABI binaries running under CONFIG_OABI_COMPAT?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261105-tonyk-syscall_table-v9-0-8d1275885d9c@igalia.com?part=14