Commit 9142be9e authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Borislav Petkov (AMD)
Browse files

x86/syscall: Mark exit[_group] syscall handlers __noreturn 

The direct-call syscall dispatch function doesn't know that the exit()
and exit_group() syscall handlers don't return, so the call sites aren't
optimized accordingly.

Fix that by marking the exit syscall declarations __noreturn.

Fixes the following warnings:

  vmlinux.o: warning: objtool: x64_sys_call+0x2804: __x64_sys_exit() is missing a __noreturn annotation
  vmlinux.o: warning: objtool: ia32_sys_call+0x29b6: __ia32_sys_exit_group() is missing a __noreturn annotation

Fixes: 1e3ad783 ("x86/syscall: Don't force use of indirect calls for system calls")
Closes: https://lkml.kernel.org/lkml/6dba9b32-db2c-4e6d-9500-7a08852f17a3@paulmck-laptop


Reported-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Tested-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/5d8882bc077d8eadcc7fd1740b56dfb781f12288.1719381528.git.jpoimboe@kernel.org
parent f2661062

arch/x86/entry/syscall_32.c

+6 −4
Original line number Diff line number Diff line
@@ -14,10 +14,13 @@ 
#endif



#define __SYSCALL(nr, sym) extern long __ia32_##sym(const struct pt_regs *);



#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __ia32_##sym(const struct pt_regs *);

#include <asm/syscalls_32.h>

#undef  __SYSCALL



#undef  __SYSCALL_NORETURN

#define __SYSCALL_NORETURN __SYSCALL



/*

 * The sys_call_table[] is no longer used for system calls, but

 * kernel/trace/trace_syscalls.c still wants to know the system
@@ -32,7 +35,6 @@ const sys_call_ptr_t sys_call_table[] = { 
#endif



#define __SYSCALL(nr, sym) case nr: return __ia32_##sym(regs);



long ia32_sys_call(const struct pt_regs *regs, unsigned int nr)

{

	switch (nr) {

arch/x86/entry/syscall_64.c

+6 −3
Original line number Diff line number Diff line
@@ -8,9 +8,13 @@ 
#include <asm/syscall.h>



#define __SYSCALL(nr, sym) extern long __x64_##sym(const struct pt_regs *);

#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __x64_##sym(const struct pt_regs *);

#include <asm/syscalls_64.h>

#undef  __SYSCALL



#undef  __SYSCALL_NORETURN

#define __SYSCALL_NORETURN __SYSCALL



/*

 * The sys_call_table[] is no longer used for system calls, but

 * kernel/trace/trace_syscalls.c still wants to know the system
@@ -23,7 +27,6 @@ const sys_call_ptr_t sys_call_table[] = { 
#undef  __SYSCALL



#define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);



long x64_sys_call(const struct pt_regs *regs, unsigned int nr)

{

	switch (nr) {

arch/x86/entry/syscall_x32.c

+5 −2
Original line number Diff line number Diff line
@@ -8,11 +8,14 @@ 
#include <asm/syscall.h>



#define __SYSCALL(nr, sym) extern long __x64_##sym(const struct pt_regs *);

#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __x64_##sym(const struct pt_regs *);

#include <asm/syscalls_x32.h>

#undef  __SYSCALL



#define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);

#undef  __SYSCALL_NORETURN

#define __SYSCALL_NORETURN __SYSCALL



#define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);

long x32_sys_call(const struct pt_regs *regs, unsigned int nr)

{

	switch (nr) {

arch/x86/entry/syscalls/syscall_32.tbl

+3 −3
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
# 32-bit system call numbers and entry vectors

#

# The format is:

# <number> <abi> <name> <entry point> <compat entry point>

# <number> <abi> <name> <entry point> [<compat entry point> [noreturn]]

#

# The __ia32_sys and __ia32_compat_sys stubs are created on-the-fly for

# sys_*() system calls and compat_sys_*() compat system calls if
@@ -12,7 +12,7 @@ 
# The abi is always "i386" for this file.

#

0	i386	restart_syscall		sys_restart_syscall

1	i386	exit			sys_exit

1	i386	exit			sys_exit			-			noreturn

2	i386	fork			sys_fork

3	i386	read			sys_read

4	i386	write			sys_write
@@ -263,7 +263,7 @@ 
249	i386	io_cancel		sys_io_cancel

250	i386	fadvise64		sys_ia32_fadvise64

# 251 is available for reuse (was briefly sys_set_zone_reclaim)

252	i386	exit_group		sys_exit_group

252	i386	exit_group		sys_exit_group			-			noreturn

253	i386	lookup_dcookie

254	i386	epoll_create		sys_epoll_create

255	i386	epoll_ctl		sys_epoll_ctl

arch/x86/entry/syscalls/syscall_64.tbl

+3 −3
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
# 64-bit system call numbers and entry vectors

#

# The format is:

# <number> <abi> <name> <entry point>

# <number> <abi> <name> <entry point> [<compat entry point> [noreturn]]

#

# The __x64_sys_*() stubs are created on-the-fly for sys_*() system calls

#
@@ -68,7 +68,7 @@ 
57	common	fork			sys_fork

58	common	vfork			sys_vfork

59	64	execve			sys_execve

60	common	exit			sys_exit

60	common	exit			sys_exit			-			noreturn

61	common	wait4			sys_wait4

62	common	kill			sys_kill

63	common	uname			sys_newuname
@@ -239,7 +239,7 @@ 
228	common	clock_gettime		sys_clock_gettime

229	common	clock_getres		sys_clock_getres

230	common	clock_nanosleep		sys_clock_nanosleep

231	common	exit_group		sys_exit_group

231	common	exit_group		sys_exit_group			-			noreturn

232	common	epoll_wait		sys_epoll_wait

233	common	epoll_ctl		sys_epoll_ctl

234	common	tgkill			sys_tgkill