Re: [PATCH v12 5/8] powerpc/64: make buildable without CONFIG_COMPAT

[Christophe Leroy <christophe.leroy@xxxxxx>]

Le 20/03/2020 à 11:20, Michal Suchanek a écrit :
> There are numerous references to 32bit functions in generic and 64bit
> code so ifdef them out.
>
> Signed-off-by: Michal Suchanek <msuchanek@xxxxxxx>
> ---
> v2:
> - fix 32bit ifdef condition in signal.c
> - simplify the compat ifdef condition in vdso.c - 64bit is redundant
> - simplify the compat ifdef condition in callchain.c - 64bit is redundant
> v3:
> - use IS_ENABLED and maybe_unused where possible
> - do not ifdef declarations
> - clean up Makefile
> v4:
> - further makefile cleanup
> - simplify is_32bit_task conditions
> - avoid ifdef in condition by using return
> v5:
> - avoid unreachable code on 32bit
> - make is_current_64bit constant on !COMPAT
> - add stub perf_callchain_user_32 to avoid some ifdefs
> v6:
> - consolidate current_is_64bit
> v7:
> - remove leftover perf_callchain_user_32 stub from previous series version
> v8:
> - fix build again - too trigger-happy with stub removal
> - remove a vdso.c hunk that causes warning according to kbuild test robot
> v9:
> - removed current_is_64bit in previous patch
> v10:
> - rebase on top of 70ed86f4de5bd
> ---
>   arch/powerpc/include/asm/thread_info.h | 4 ++--
>   arch/powerpc/kernel/Makefile           | 6 +++---
>   arch/powerpc/kernel/entry_64.S         | 2 ++
>   arch/powerpc/kernel/signal.c           | 3 +--
>   arch/powerpc/kernel/syscall_64.c       | 6 ++----
>   arch/powerpc/kernel/vdso.c             | 3 ++-
>   arch/powerpc/perf/callchain.c          | 8 +++++++-
>   7 files changed, 19 insertions(+), 13 deletions(-)

[...]

> diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
> index 87d95b455b83..2dcbfe38f5ac 100644
> --- a/arch/powerpc/kernel/syscall_64.c
> +++ b/arch/powerpc/kernel/syscall_64.c
> @@ -24,7 +24,6 @@ notrace long system_call_exception(long r3, long r4, long r5,
>   				   long r6, long r7, long r8,
>   				   unsigned long r0, struct pt_regs *regs)
>   {
> -	unsigned long ti_flags;
>   	syscall_fn f;
>   
>   	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
> @@ -68,8 +67,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
>   
>   	local_irq_enable();
>   
> -	ti_flags = current_thread_info()->flags;
> -	if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
> +	if (unlikely(current_thread_info()->flags & _TIF_SYSCALL_DOTRACE)) {
>   		/*
>   		 * We use the return value of do_syscall_trace_enter() as the
>   		 * syscall number. If the syscall was rejected for any reason
> @@ -94,7 +92,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
>   	/* May be faster to do array_index_nospec? */
>   	barrier_nospec();
>   
> -	if (unlikely(ti_flags & _TIF_32BIT)) {
> +	if (unlikely(is_32bit_task())) {

is_compat() should be used here instead, because we dont want to use 
compat_sys_call_table() on PPC32.

>   		f = (void *)compat_sys_call_table[r0];
>   
>   		r3 &= 0x00000000ffffffffULL;

Christophe