syscall.h: introduce syscall_set_nr()

Similar to syscall_set_arguments() that complements
syscall_get_arguments(), introduce syscall_set_nr() that complements
syscall_get_nr().

syscall_set_nr() is going to be needed along with syscall_set_arguments()
on all HAVE_ARCH_TRACEHOOK architectures to implement
PTRACE_SET_SYSCALL_INFO API.

Link: https://lkml.kernel.org/r/20250303112020.GD24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk> # mips
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 292b412f4e9a..c5a3ad53beec 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -38,6 +38,20 @@ struct pt_regs;
 int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
 
 /**
+ * syscall_set_nr - change the system call a task is executing
+ * @task:	task of interest, must be blocked
+ * @regs:	task_pt_regs() of @task
+ * @nr:		system call number
+ *
+ * Changes the system call number @task is about to execute.
+ *
+ * It's only valid to call this when @task is stopped for tracing on
+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
+ */
+void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr);
+
+/**
  * syscall_rollback - roll back registers after an aborted system call
  * @task:	task of interest, must be in system call exit tracing
  * @regs:	task_pt_regs() of @task