I'm surprised this one hasn't looped around via
-stable.
I'm tempted to wait and see if it does come via
this channel, since this hasn't caused us any
issues so far in the 6.6 kernel cycle.
... but i'm technically on vacation, so it will
be a wile before I check -stable, so I've gone
ahead and merged this and will keep an eye out
for merge conflicts.
Bruce
In message: [linux-yocto][linux-yocto v6.6/standard/base][PATCH] x86/syscall:
Mark exit[_group] syscall handlers __noreturn
on 21/08/2024 Xiangyu Chen via lists.yoctoproject.org wrote:
> From: Josh Poimboeuf <jpoim...@kernel.org>
>
> [ Upstream commit 9142be9e6443fd641ca37f820efe00d9cd890eb1 ]
>
> 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: 1e3ad78334a6 ("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: Paul E. McKenney <paul...@kernel.org>
> Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org>
> Signed-off-by: Borislav Petkov (AMD) <b...@alien8.de>
> Tested-by: Paul E. McKenney <paul...@kernel.org>
> Link:
> https://lore.kernel.org/r/5d8882bc077d8eadcc7fd1740b56dfb781f12288.1719381528.git.jpoim...@kernel.org
>
> (Adapted the context line number in syscall_32.tbl and noreturns.h.)
> Signed-off-by: Xiangyu Chen <xiangyu.c...@windriver.com>
> ---
> arch/x86/entry/syscall_32.c | 10 ++++++----
> arch/x86/entry/syscall_64.c | 9 ++++++---
> arch/x86/entry/syscall_x32.c | 7 +++++--
> arch/x86/entry/syscalls/syscall_32.tbl | 6 +++---
> arch/x86/entry/syscalls/syscall_64.tbl | 6 +++---
> arch/x86/um/sys_call_table_32.c | 10 ++++++----
> arch/x86/um/sys_call_table_64.c | 11 +++++++----
> scripts/syscalltbl.sh | 18 ++++++++++++++++--
> tools/objtool/noreturns.h | 4 ++++
> 9 files changed, 56 insertions(+), 25 deletions(-)
>
> diff --git a/arch/x86/entry/syscall_32.c b/arch/x86/entry/syscall_32.c
> index c2235bae17ef..8cc9950d7104 100644
> --- a/arch/x86/entry/syscall_32.c
> +++ b/arch/x86/entry/syscall_32.c
> @@ -14,9 +14,12 @@
> #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
> +
> +#undef __SYSCALL_NORETURN
> +#define __SYSCALL_NORETURN __SYSCALL
>
> /*
> * The sys_call_table[] is no longer used for system calls, but
> @@ -28,11 +31,10 @@
> const sys_call_ptr_t sys_call_table[] = {
> #include <asm/syscalls_32.h>
> };
> -#undef __SYSCALL
> +#undef __SYSCALL
> #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) {
> diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
> index 33b3f09e6f15..ba8354424860 100644
> --- a/arch/x86/entry/syscall_64.c
> +++ b/arch/x86/entry/syscall_64.c
> @@ -8,8 +8,12 @@
> #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
> +
> +#undef __SYSCALL_NORETURN
> +#define __SYSCALL_NORETURN __SYSCALL
>
> /*
> * The sys_call_table[] is no longer used for system calls, but
> @@ -20,10 +24,9 @@
> const sys_call_ptr_t sys_call_table[] = {
> #include <asm/syscalls_64.h>
> };
> -#undef __SYSCALL
> +#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) {
> diff --git a/arch/x86/entry/syscall_x32.c b/arch/x86/entry/syscall_x32.c
> index 03de4a932131..fb77908f44f3 100644
> --- a/arch/x86/entry/syscall_x32.c
> +++ b/arch/x86/entry/syscall_x32.c
> @@ -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
> +#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) {
> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl
> b/arch/x86/entry/syscalls/syscall_32.tbl
> index 38db5ef2329f..2f96923ba030 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -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 sys_lookup_dcookie
> compat_sys_lookup_dcookie
> 254 i386 epoll_create sys_epoll_create
> 255 i386 epoll_ctl sys_epoll_ctl
> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl
> b/arch/x86/entry/syscalls/syscall_64.tbl
> index 1d6eee30eceb..d19d71e4058d 100644
> --- a/arch/x86/entry/syscalls/syscall_64.tbl
> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> @@ -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
> diff --git a/arch/x86/um/sys_call_table_32.c b/arch/x86/um/sys_call_table_32.c
> index 89df5d89d664..51655133eee3 100644
> --- a/arch/x86/um/sys_call_table_32.c
> +++ b/arch/x86/um/sys_call_table_32.c
> @@ -9,6 +9,10 @@
> #include <linux/cache.h>
> #include <asm/syscall.h>
>
> +extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long,
> + unsigned long, unsigned long,
> + unsigned long, unsigned long);
> +
> /*
> * Below you can see, in terms of #define's, the differences between the
> x86-64
> * and the UML syscall table.
> @@ -22,15 +26,13 @@
> #define sys_vm86 sys_ni_syscall
>
> #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
> +#define __SYSCALL_NORETURN __SYSCALL
>
> #define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long,
> unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
> #include <asm/syscalls_32.h>
> +#undef __SYSCALL
>
> -#undef __SYSCALL
> #define __SYSCALL(nr, sym) sym,
> -
> -extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned
> long, unsigned long, unsigned long, unsigned long);
> -
> const sys_call_ptr_t sys_call_table[] ____cacheline_aligned = {
> #include <asm/syscalls_32.h>
> };
> diff --git a/arch/x86/um/sys_call_table_64.c b/arch/x86/um/sys_call_table_64.c
> index b0b4cfd2308c..943d414f2109 100644
> --- a/arch/x86/um/sys_call_table_64.c
> +++ b/arch/x86/um/sys_call_table_64.c
> @@ -9,6 +9,10 @@
> #include <linux/cache.h>
> #include <asm/syscall.h>
>
> +extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long,
> + unsigned long, unsigned long,
> + unsigned long, unsigned long);
> +
> /*
> * Below you can see, in terms of #define's, the differences between the
> x86-64
> * and the UML syscall table.
> @@ -18,14 +22,13 @@
> #define sys_iopl sys_ni_syscall
> #define sys_ioperm sys_ni_syscall
>
> +#define __SYSCALL_NORETURN __SYSCALL
> +
> #define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long,
> unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
> #include <asm/syscalls_64.h>
> +#undef __SYSCALL
>
> -#undef __SYSCALL
> #define __SYSCALL(nr, sym) sym,
> -
> -extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned
> long, unsigned long, unsigned long, unsigned long);
> -
> const sys_call_ptr_t sys_call_table[] ____cacheline_aligned = {
> #include <asm/syscalls_64.h>
> };
> diff --git a/scripts/syscalltbl.sh b/scripts/syscalltbl.sh
> index 6abe143889ef..6a903b87a7c2 100755
> --- a/scripts/syscalltbl.sh
> +++ b/scripts/syscalltbl.sh
> @@ -54,7 +54,7 @@ nxt=0
>
> grep -E "^[0-9]+[[:space:]]+$abis" "$infile" | {
>
> - while read nr abi name native compat ; do
> + while read nr abi name native compat noreturn; do
>
> if [ $nxt -gt $nr ]; then
> echo "error: $infile: syscall table is not sorted or
> duplicates the same syscall number" >&2
> @@ -66,7 +66,21 @@ grep -E "^[0-9]+[[:space:]]+$abis" "$infile" | {
> nxt=$((nxt + 1))
> done
>
> - if [ -n "$compat" ]; then
> + if [ "$compat" = "-" ]; then
> + unset compat
> + fi
> +
> + if [ -n "$noreturn" ]; then
> + if [ "$noreturn" != "noreturn" ]; then
> + echo "error: $infile: invalid string
> \"$noreturn\" in 'noreturn' column"
> + exit 1
> + fi
> + if [ -n "$compat" ]; then
> + echo "__SYSCALL_COMPAT_NORETURN($nr, $native,
> $compat)"
> + else
> + echo "__SYSCALL_NORETURN($nr, $native)"
> + fi
> + elif [ -n "$compat" ]; then
> echo "__SYSCALL_WITH_COMPAT($nr, $native, $compat)"
> elif [ -n "$native" ]; then
> echo "__SYSCALL($nr, $native)"
> diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h
> index 80a3e6acf31e..e1ab46f875d1 100644
> --- a/tools/objtool/noreturns.h
> +++ b/tools/objtool/noreturns.h
> @@ -12,6 +12,8 @@ NORETURN(__reiserfs_panic)
> NORETURN(__stack_chk_fail)
> NORETURN(__ubsan_handle_builtin_unreachable)
> NORETURN(arch_call_rest_init)
> +NORETURN(__x64_sys_exit)
> +NORETURN(__x64_sys_exit_group)
> NORETURN(arch_cpu_idle_dead)
> NORETURN(cpu_bringup_and_idle)
> NORETURN(cpu_startup_entry)
> @@ -20,6 +22,8 @@ NORETURN(do_group_exit)
> NORETURN(do_task_dead)
> NORETURN(ex_handler_msr_mce)
> NORETURN(fortify_panic)
> +NORETURN(__ia32_sys_exit)
> +NORETURN(__ia32_sys_exit_group)
> NORETURN(hlt_play_dead)
> NORETURN(hv_ghcb_terminate)
> NORETURN(kthread_complete_and_exit)
> --
> 2.25.1
>
>
>
>
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