6.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Josh Poimboeuf jpoimboe@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-la... Reported-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Tested-by: Paul E. McKenney paulmck@kernel.org Link: https://lore.kernel.org/r/5d8882bc077d8eadcc7fd1740b56dfb781f12288.171938152... Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c2235bae17ef6..8cc9950d7104a 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 33b3f09e6f151..ba8354424860c 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 03de4a9321318..fb77908f44f37 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 d6ebcab1d8b28..4b71a2607bf58 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 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 a396f6e6ab5bf..a8068f937290a 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 89df5d89d6640..51655133eee36 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 b0b4cfd2308c8..943d414f21093 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 6abe143889ef6..6a903b87a7c21 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 7ebf29c911849..1e8141ef1b15d 100644 --- a/tools/objtool/noreturns.h +++ b/tools/objtool/noreturns.h @@ -7,12 +7,16 @@ * Yes, this is unfortunate. A better solution is in the works. */ NORETURN(__fortify_panic) +NORETURN(__ia32_sys_exit) +NORETURN(__ia32_sys_exit_group) NORETURN(__kunit_abort) NORETURN(__module_put_and_kthread_exit) NORETURN(__reiserfs_panic) NORETURN(__stack_chk_fail) NORETURN(__tdx_hypercall_failed) NORETURN(__ubsan_handle_builtin_unreachable) +NORETURN(__x64_sys_exit) +NORETURN(__x64_sys_exit_group) NORETURN(arch_cpu_idle_dead) NORETURN(bch2_trans_in_restart_error) NORETURN(bch2_trans_restart_error)