Re: [PATCH v7 4/6] powerpc/64: make buildable without CONFIG_COMPAT

[Christophe Leroy <christophe.leroy@c-s.fr>]

Le 30/08/2019 à 23:03, 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@suse.de>

Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

> ---
> 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
> ---
>   arch/powerpc/include/asm/thread_info.h |  4 ++--
>   arch/powerpc/kernel/Makefile           |  7 +++---
>   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             |  5 ++---
>   arch/powerpc/perf/callchain.c          | 31 +++++++++++++-------------
>   7 files changed, 27 insertions(+), 31 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
> index 8e1d0195ac36..c128d8a48ea3 100644
> --- a/arch/powerpc/include/asm/thread_info.h
> +++ b/arch/powerpc/include/asm/thread_info.h
> @@ -144,10 +144,10 @@ static inline bool test_thread_local_flags(unsigned int flags)
>   	return (ti->local_flags & flags) != 0;
>   }
>   
> -#ifdef CONFIG_PPC64
> +#ifdef CONFIG_COMPAT
>   #define is_32bit_task()	(test_thread_flag(TIF_32BIT))
>   #else
> -#define is_32bit_task()	(1)
> +#define is_32bit_task()	(IS_ENABLED(CONFIG_PPC32))
>   #endif
>   
>   #if defined(CONFIG_PPC64)
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 1d646a94d96c..9d8772e863b9 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -44,16 +44,15 @@ CFLAGS_btext.o += -DDISABLE_BRANCH_PROFILING
>   endif
>   
>   obj-y				:= cputable.o ptrace.o syscalls.o \
> -				   irq.o align.o signal_32.o pmc.o vdso.o \
> +				   irq.o align.o signal_$(BITS).o pmc.o vdso.o \
>   				   process.o systbl.o idle.o \
>   				   signal.o sysfs.o cacheinfo.o time.o \
>   				   prom.o traps.o setup-common.o \
>   				   udbg.o misc.o io.o misc_$(BITS).o \
>   				   of_platform.o prom_parse.o
> -obj-$(CONFIG_PPC64)		+= setup_64.o sys_ppc32.o \
> -				   signal_64.o ptrace32.o \
> -				   paca.o nvram_64.o firmware.o \
> +obj-$(CONFIG_PPC64)		+= setup_64.o paca.o nvram_64.o firmware.o \
>   				   syscall_64.o
> +obj-$(CONFIG_COMPAT)		+= sys_ppc32.o ptrace32.o signal_32.o
>   obj-$(CONFIG_VDSO32)		+= vdso32/
>   obj-$(CONFIG_PPC_WATCHDOG)	+= watchdog.o
>   obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
> index 2ec825a85f5b..a2dbf216f607 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -51,8 +51,10 @@
>   SYS_CALL_TABLE:
>   	.tc sys_call_table[TC],sys_call_table
>   
> +#ifdef CONFIG_COMPAT
>   COMPAT_SYS_CALL_TABLE:
>   	.tc compat_sys_call_table[TC],compat_sys_call_table
> +#endif
>   
>   /* This value is used to mark exception frames on the stack. */
>   exception_marker:
> diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
> index 60436432399f..61678cb0e6a1 100644
> --- a/arch/powerpc/kernel/signal.c
> +++ b/arch/powerpc/kernel/signal.c
> @@ -247,7 +247,6 @@ static void do_signal(struct task_struct *tsk)
>   	sigset_t *oldset = sigmask_to_save();
>   	struct ksignal ksig = { .sig = 0 };
>   	int ret;
> -	int is32 = is_32bit_task();
>   
>   	BUG_ON(tsk != current);
>   
> @@ -277,7 +276,7 @@ static void do_signal(struct task_struct *tsk)
>   
>   	rseq_signal_deliver(&ksig, tsk->thread.regs);
>   
> -	if (is32) {
> +	if (is_32bit_task()) {
>           	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
>   			ret = handle_rt_signal32(&ksig, oldset, tsk);
>   		else
> diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
> index 98ed970796d5..0d5cbbe54cf1 100644
> --- a/arch/powerpc/kernel/syscall_64.c
> +++ b/arch/powerpc/kernel/syscall_64.c
> @@ -38,7 +38,6 @@ typedef long (*syscall_fn)(long, long, long, long, long, long);
>   
>   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;
>   
>   	BUG_ON(!(regs->msr & MSR_PR));
> @@ -83,8 +82,7 @@ long system_call_exception(long r3, long r4, long r5, long r6, long r7, long r8,
>   	 */
>   	regs->softe = IRQS_ENABLED;
>   
> -	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
> @@ -100,7 +98,7 @@ long system_call_exception(long r3, long r4, long r5, long r6, long r7, long r8,
>   	/* May be faster to do array_index_nospec? */
>   	barrier_nospec();
>   
> -	if (unlikely(ti_flags & _TIF_32BIT)) {
> +	if (unlikely(is_32bit_task())) {
>   		f = (void *)compat_sys_call_table[r0];
>   
>   		r3 &= 0x00000000ffffffffULL;
> diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
> index d60598113a9f..6d4a077f74d6 100644
> --- a/arch/powerpc/kernel/vdso.c
> +++ b/arch/powerpc/kernel/vdso.c
> @@ -667,9 +667,7 @@ static void __init vdso_setup_syscall_map(void)
>   {
>   	unsigned int i;
>   	extern unsigned long *sys_call_table;
> -#ifdef CONFIG_PPC64
>   	extern unsigned long *compat_sys_call_table;
> -#endif
>   	extern unsigned long sys_ni_syscall;
>   
>   
> @@ -678,7 +676,8 @@ static void __init vdso_setup_syscall_map(void)
>   		if (sys_call_table[i] != sys_ni_syscall)
>   			vdso_data->syscall_map_64[i >> 5] |=
>   				0x80000000UL >> (i & 0x1f);
> -		if (compat_sys_call_table[i] != sys_ni_syscall)
> +		if (IS_ENABLED(CONFIG_COMPAT) &&
> +		    compat_sys_call_table[i] != sys_ni_syscall)
>   			vdso_data->syscall_map_32[i >> 5] |=
>   				0x80000000UL >> (i & 0x1f);
>   #else /* CONFIG_PPC64 */
> diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
> index b7cdcce20280..9b8dc822f531 100644
> --- a/arch/powerpc/perf/callchain.c
> +++ b/arch/powerpc/perf/callchain.c
> @@ -15,7 +15,7 @@
>   #include <asm/sigcontext.h>
>   #include <asm/ucontext.h>
>   #include <asm/vdso.h>
> -#ifdef CONFIG_PPC64
> +#ifdef CONFIG_COMPAT
>   #include "../kernel/ppc32.h"
>   #endif
>   #include <asm/pte-walk.h>
> @@ -268,16 +268,6 @@ static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
>   	}
>   }
>   
> -static inline int current_is_64bit(void)
> -{
> -	/*
> -	 * We can't use test_thread_flag() here because we may be on an
> -	 * interrupt stack, and the thread flags don't get copied over
> -	 * from the thread_info on the main stack to the interrupt stack.
> -	 */
> -	return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
> -}
> -
>   #else  /* CONFIG_PPC64 */
>   static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
>   {
> @@ -314,11 +304,6 @@ static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry
>   {
>   }
>   
> -static inline int current_is_64bit(void)
> -{
> -	return 0;
> -}
> -
>   static inline int valid_user_sp(unsigned long sp, int is_64)
>   {
>   	if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
> @@ -334,6 +319,7 @@ static inline int valid_user_sp(unsigned long sp, int is_64)
>   
>   #endif /* CONFIG_PPC64 */
>   
> +#if defined(CONFIG_PPC32) || defined(CONFIG_COMPAT)
>   /*
>    * Layout for non-RT signal frames
>    */
> @@ -475,6 +461,19 @@ static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
>   		sp = next_sp;
>   	}
>   }
> +#endif /* 32bit */
> +
> +static inline int current_is_64bit(void)
> +{
> +	if (!IS_ENABLED(CONFIG_COMPAT))
> +		return IS_ENABLED(CONFIG_PPC64);
> +	/*
> +	 * We can't use test_thread_flag() here because we may be on an
> +	 * interrupt stack, and the thread flags don't get copied over
> +	 * from the thread_info on the main stack to the interrupt stack.
> +	 */
> +	return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
> +}
>   
>   void
>   perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
>