Re: [PATCH v6 1/3] x86/syscall: Mark exit[_group] syscall handlers __noreturn

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Jun 25, 2024 at 11:02:00PM -0700, Josh Poimboeuf wrote:
> 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: 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
> Tested-by: Paul E. McKenney <paulmck@kernel.org>
> Signed-off-by: Josh Poimboeuf <jpoimboe@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(-)


Hi,

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