On Thu, 29 Aug 2019 19:40:55 +0200
Christophe Leroy [off-list ref] wrote:

Le 29/08/2019 à 12:23, Michal Suchanek a écrit :

quoted

There are numerous references to 32bit functions in generic and 64bit
code so ifdef them out.

Signed-off-by: Michal Suchanek <redacted>
---
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
---
  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          | 14 ++++++++++----
  7 files changed, 22 insertions(+), 19 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 c84bbd4298a0..aef8c750d242 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  

Is this ifdef needed at all ? Is it a problem to include it all the time ?

Yes, it is a problem. Some 32bit structures are not defined giving an
error.

quoted

  #include "../kernel/ppc32.h"
  #endif
  #include <asm/pte-walk.h>

@@ -165,6 +165,7 @@ static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
  	return read_user_stack_slow(ptr, ret, 8);
  }
  
+__maybe_unused  

I don't like that too much. I see this function is almost identical 
between PPC64 and PPC32. It should be possible to have only one, using 
IS_ENABLED(CONFIG_PPC64) inside it to call read_user_stack_slow().
An define a dummy read_user_stack_slow() for PPC32 as already done for 
perf_callchain_user_64().

We need to #ifdef the block below anyway because it needs 32bit
structures defined which aren't. So can add usage there.

quoted

  static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
  {
  	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||

@@ -341,6 +342,7 @@ 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
   */

@@ -482,12 +484,16 @@ static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
  		sp = next_sp;
  	}
  }
+#endif /* 32bit */
  
  void
  perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
  {
-	if (current_is_64bit())
-		perf_callchain_user_64(entry, regs);
-	else
+#if defined(CONFIG_PPC32) || defined(CONFIG_COMPAT)
+	if (!current_is_64bit()) {
  		perf_callchain_user_32(entry, regs);
+		return;
+	}
+#endif
+	perf_callchain_user_64(entry, regs);
  }
  

Instead of that it could just be:

	if (current_is_64bit())
		perf_callchain_user_64(entry, regs);
	else
		perf_callchain_user_32(entry, regs);


By adding a dummy perf_callchain_user_32() when needed as already done 
for perf_callchain_user_64()

and it can do a dummy use of the function above as well.

And by making sure current_is_64bit() returns IS_ENABLED(CONFIG_PPC64) 
when CONFIG_COMPAT is not set, on the same principle as you did for 
is_32bit_task()

Yes, that would make it constant for the !COMPAT cases.

And maybe you could think about spliting callchain.c out in a 
callchain_32.c and a callchain_64.c that gets selected by the Makefiles 
based on the same principle as you did for ptrace_32.c etc...

I actually did not split those. Can look how splitting is done there
and if it can be applied to the callchain situation.

Thanks

Michal