Messages in this thread | | | Date | Sat, 20 Apr 2024 06:58:58 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v4 3/5] x86/syscall: Mark exit[_group] syscall handlers __noreturn |
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On Fri, Apr 19, 2024 at 02:09:49PM -0700, Josh Poimboeuf wrote: > The direct-call syscall dispatch functions don't know that the exit() > and exit_group() syscall handlers don't return. As a result the call > sites aren't optimized accordingly. > > Fix that by marking those exit syscall declarations as __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: 7390db8aea0d ("x86/bhi: Add support for clearing branch history at syscall entry") > Reported-by: "Paul E. McKenney" <paulmck@kernel.org> > Closes: https://lkml.kernel.org/lkml/6dba9b32-db2c-4e6d-9500-7a08852f17a3@paulmck-laptop > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Looks good, but it does not apply on top of current -next and I don't trust myself to hand-apply it (something about having just got off of a flight across the big pond).
Could you please let me know what else do I need to pull in to be able to cleanly apply this one?
Thanx, Paul
> --- > arch/x86/entry/syscall_64.c | 4 ++++ > arch/x86/entry/syscall_x32.c | 4 ++++ > arch/x86/entry/syscalls/syscall_64.tbl | 6 +++--- > arch/x86/um/sys_call_table_32.c | 1 + > arch/x86/um/sys_call_table_64.c | 1 + > scripts/syscalltbl.sh | 6 ++++-- > tools/objtool/noreturns.h | 4 ++++ > 7 files changed, 21 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c > index 96ea1f8a1d3f..ff36a993a07e 100644 > --- a/arch/x86/entry/syscall_64.c > +++ b/arch/x86/entry/syscall_64.c > @@ -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 > + > #define __SYSCALL(nr, sym) __x64_##sym, > const sys_call_ptr_t sys_call_table[] = { > #include <asm/syscalls_64.h> > diff --git a/arch/x86/entry/syscall_x32.c b/arch/x86/entry/syscall_x32.c > index 5aef4230faca..4221ecce6e68 100644 > --- a/arch/x86/entry/syscall_x32.c > +++ b/arch/x86/entry/syscall_x32.c > @@ -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_x32.h> > #undef __SYSCALL > > +#undef __SYSCALL_NORETURN > +#define __SYSCALL_NORETURN __SYSCALL > + > #define __SYSCALL(nr, sym) __x64_##sym, > const sys_call_ptr_t x32_sys_call_table[] = { > #include <asm/syscalls_x32.h> > diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl > index 7e8d46f4147f..6695105d21b5 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> [0 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 0 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 0 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..c7d4bf955d2b 100644 > --- a/arch/x86/um/sys_call_table_32.c > +++ b/arch/x86/um/sys_call_table_32.c > @@ -24,6 +24,7 @@ > #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) > > #define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); > +#define __SYSCALL_NORETURN __SYSCALL > #include <asm/syscalls_32.h> > > #undef __SYSCALL > diff --git a/arch/x86/um/sys_call_table_64.c b/arch/x86/um/sys_call_table_64.c > index b0b4cfd2308c..4760c40ae5cd 100644 > --- a/arch/x86/um/sys_call_table_64.c > +++ b/arch/x86/um/sys_call_table_64.c > @@ -19,6 +19,7 @@ > #define sys_ioperm sys_ni_syscall > > #define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); > +#define __SYSCALL_NORETURN __SYSCALL > #include <asm/syscalls_64.h> > > #undef __SYSCALL > diff --git a/scripts/syscalltbl.sh b/scripts/syscalltbl.sh > index 6abe143889ef..16487d47e06a 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: $infile: syscall table is not sorted or duplicates the same syscall number" >&2 > @@ -66,7 +66,9 @@ grep -E "^[0-9]+[[:space:]]+$abis" "$infile" | { > nxt=$((nxt + 1)) > done > > - if [ -n "$compat" ]; then > + if [ -n "$noreturn" ]; then > + echo "__SYSCALL_NORETURN($nr, $native)" > + elif [ -n "$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 7ebf29c91184..1e8141ef1b15 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) > -- > 2.44.0 >
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