[PATCH v4 0/4] Disable compat cruft on ppc64le v4

[PATCH v4 0/4] Disable compat cruft on ppc64le v4

[Michal Suchanek]

Less code means less bugs so add a knob to skip the compat stuff.

This is tested on ppc64le top of

https://patchwork.ozlabs.org/cover/1153556/

Changes in v2: saner CONFIG_COMPAT ifdefs
Changes in v3:
 - change llseek to 32bit instead of builing it unconditionally in fs
 - clanup the makefile conditionals
 - remove some ifdefs or convert to IS_DEFINED where possible
Changes in v4:
 - cleanup is_32bit_task and current_is_64bit
 - more makefile cleanup

Michal Suchanek (4):
  powerpc: make llseek 32bit-only.
  powerpc: move common register copy functions from signal_32.c to
    signal.c
  powerpc/64: make buildable without CONFIG_COMPAT
  powerpc/64: Make COMPAT user-selectable disabled on littleendian by
    default.

 arch/powerpc/Kconfig                     |   5 +-
 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             | 144 ++++++++++++++++++++++-
 arch/powerpc/kernel/signal_32.c          | 140 ----------------------
 arch/powerpc/kernel/syscall_64.c         |   6 +-
 arch/powerpc/kernel/syscalls/syscall.tbl |   2 +-
 arch/powerpc/kernel/vdso.c               |   5 +-
 arch/powerpc/perf/callchain.c            |  14 ++-
 10 files changed, 167 insertions(+), 162 deletions(-)

-- 
2.22.0

[PATCH v4 1/4] powerpc: make llseek 32bit-only.

[Michal Suchanek]

Fixes: aff850393200 ("powerpc: add system call table generation support")

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/syscalls/syscall.tbl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index 010b9f445586..53e427606f6c 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -188,7 +188,7 @@
 137	common	afs_syscall			sys_ni_syscall
 138	common	setfsuid			sys_setfsuid
 139	common	setfsgid			sys_setfsgid
-140	common	_llseek				sys_llseek
+140	32	_llseek				sys_llseek
 141	common	getdents			sys_getdents			compat_sys_getdents
 142	common	_newselect			sys_select			compat_sys_select
 143	common	flock				sys_flock
-- 
2.22.0

[PATCH v4 2/4] powerpc: move common register copy functions from signal_32.c to signal.c

[Michal Suchanek]

These functions are required for 64bit as well.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/signal.c    | 141 ++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/signal_32.c | 140 -------------------------------
 2 files changed, 141 insertions(+), 140 deletions(-)

diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index e6c30cee6abf..60436432399f 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -18,12 +18,153 @@
 #include <linux/syscalls.h>
 #include <asm/hw_breakpoint.h>
 #include <linux/uaccess.h>
+#include <asm/switch_to.h>
 #include <asm/unistd.h>
 #include <asm/debug.h>
 #include <asm/tm.h>
 
 #include "signal.h"
 
+#ifdef CONFIG_VSX
+unsigned long copy_fpr_to_user(void __user *to,
+			       struct task_struct *task)
+{
+	u64 buf[ELF_NFPREG];
+	int i;
+
+	/* save FPR copy to local buffer then write to the thread_struct */
+	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
+		buf[i] = task->thread.TS_FPR(i);
+	buf[i] = task->thread.fp_state.fpscr;
+	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
+}
+
+unsigned long copy_fpr_from_user(struct task_struct *task,
+				 void __user *from)
+{
+	u64 buf[ELF_NFPREG];
+	int i;
+
+	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
+		return 1;
+	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
+		task->thread.TS_FPR(i) = buf[i];
+	task->thread.fp_state.fpscr = buf[i];
+
+	return 0;
+}
+
+unsigned long copy_vsx_to_user(void __user *to,
+			       struct task_struct *task)
+{
+	u64 buf[ELF_NVSRHALFREG];
+	int i;
+
+	/* save FPR copy to local buffer then write to the thread_struct */
+	for (i = 0; i < ELF_NVSRHALFREG; i++)
+		buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
+	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
+}
+
+unsigned long copy_vsx_from_user(struct task_struct *task,
+				 void __user *from)
+{
+	u64 buf[ELF_NVSRHALFREG];
+	int i;
+
+	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
+		return 1;
+	for (i = 0; i < ELF_NVSRHALFREG ; i++)
+		task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
+	return 0;
+}
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+unsigned long copy_ckfpr_to_user(void __user *to,
+				  struct task_struct *task)
+{
+	u64 buf[ELF_NFPREG];
+	int i;
+
+	/* save FPR copy to local buffer then write to the thread_struct */
+	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
+		buf[i] = task->thread.TS_CKFPR(i);
+	buf[i] = task->thread.ckfp_state.fpscr;
+	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
+}
+
+unsigned long copy_ckfpr_from_user(struct task_struct *task,
+					  void __user *from)
+{
+	u64 buf[ELF_NFPREG];
+	int i;
+
+	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
+		return 1;
+	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
+		task->thread.TS_CKFPR(i) = buf[i];
+	task->thread.ckfp_state.fpscr = buf[i];
+
+	return 0;
+}
+
+unsigned long copy_ckvsx_to_user(void __user *to,
+				  struct task_struct *task)
+{
+	u64 buf[ELF_NVSRHALFREG];
+	int i;
+
+	/* save FPR copy to local buffer then write to the thread_struct */
+	for (i = 0; i < ELF_NVSRHALFREG; i++)
+		buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
+	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
+}
+
+unsigned long copy_ckvsx_from_user(struct task_struct *task,
+					  void __user *from)
+{
+	u64 buf[ELF_NVSRHALFREG];
+	int i;
+
+	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
+		return 1;
+	for (i = 0; i < ELF_NVSRHALFREG ; i++)
+		task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
+	return 0;
+}
+#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
+#else
+inline unsigned long copy_fpr_to_user(void __user *to,
+				      struct task_struct *task)
+{
+	return __copy_to_user(to, task->thread.fp_state.fpr,
+			      ELF_NFPREG * sizeof(double));
+}
+
+inline unsigned long copy_fpr_from_user(struct task_struct *task,
+					void __user *from)
+{
+	return __copy_from_user(task->thread.fp_state.fpr, from,
+			      ELF_NFPREG * sizeof(double));
+}
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+inline unsigned long copy_ckfpr_to_user(void __user *to,
+					 struct task_struct *task)
+{
+	return __copy_to_user(to, task->thread.ckfp_state.fpr,
+			      ELF_NFPREG * sizeof(double));
+}
+
+inline unsigned long copy_ckfpr_from_user(struct task_struct *task,
+						 void __user *from)
+{
+	return __copy_from_user(task->thread.ckfp_state.fpr, from,
+				ELF_NFPREG * sizeof(double));
+}
+#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
+#endif
+
 /* Log an error when sending an unhandled signal to a process. Controlled
  * through debug.exception-trace sysctl.
  */
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 98600b276f76..c93c937ea568 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -235,146 +235,6 @@ struct rt_sigframe {
 	int			abigap[56];
 };
 
-#ifdef CONFIG_VSX
-unsigned long copy_fpr_to_user(void __user *to,
-			       struct task_struct *task)
-{
-	u64 buf[ELF_NFPREG];
-	int i;
-
-	/* save FPR copy to local buffer then write to the thread_struct */
-	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
-		buf[i] = task->thread.TS_FPR(i);
-	buf[i] = task->thread.fp_state.fpscr;
-	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
-}
-
-unsigned long copy_fpr_from_user(struct task_struct *task,
-				 void __user *from)
-{
-	u64 buf[ELF_NFPREG];
-	int i;
-
-	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
-		return 1;
-	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
-		task->thread.TS_FPR(i) = buf[i];
-	task->thread.fp_state.fpscr = buf[i];
-
-	return 0;
-}
-
-unsigned long copy_vsx_to_user(void __user *to,
-			       struct task_struct *task)
-{
-	u64 buf[ELF_NVSRHALFREG];
-	int i;
-
-	/* save FPR copy to local buffer then write to the thread_struct */
-	for (i = 0; i < ELF_NVSRHALFREG; i++)
-		buf[i] = task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
-	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
-}
-
-unsigned long copy_vsx_from_user(struct task_struct *task,
-				 void __user *from)
-{
-	u64 buf[ELF_NVSRHALFREG];
-	int i;
-
-	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
-		return 1;
-	for (i = 0; i < ELF_NVSRHALFREG ; i++)
-		task->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
-	return 0;
-}
-
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-unsigned long copy_ckfpr_to_user(void __user *to,
-				  struct task_struct *task)
-{
-	u64 buf[ELF_NFPREG];
-	int i;
-
-	/* save FPR copy to local buffer then write to the thread_struct */
-	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
-		buf[i] = task->thread.TS_CKFPR(i);
-	buf[i] = task->thread.ckfp_state.fpscr;
-	return __copy_to_user(to, buf, ELF_NFPREG * sizeof(double));
-}
-
-unsigned long copy_ckfpr_from_user(struct task_struct *task,
-					  void __user *from)
-{
-	u64 buf[ELF_NFPREG];
-	int i;
-
-	if (__copy_from_user(buf, from, ELF_NFPREG * sizeof(double)))
-		return 1;
-	for (i = 0; i < (ELF_NFPREG - 1) ; i++)
-		task->thread.TS_CKFPR(i) = buf[i];
-	task->thread.ckfp_state.fpscr = buf[i];
-
-	return 0;
-}
-
-unsigned long copy_ckvsx_to_user(void __user *to,
-				  struct task_struct *task)
-{
-	u64 buf[ELF_NVSRHALFREG];
-	int i;
-
-	/* save FPR copy to local buffer then write to the thread_struct */
-	for (i = 0; i < ELF_NVSRHALFREG; i++)
-		buf[i] = task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
-	return __copy_to_user(to, buf, ELF_NVSRHALFREG * sizeof(double));
-}
-
-unsigned long copy_ckvsx_from_user(struct task_struct *task,
-					  void __user *from)
-{
-	u64 buf[ELF_NVSRHALFREG];
-	int i;
-
-	if (__copy_from_user(buf, from, ELF_NVSRHALFREG * sizeof(double)))
-		return 1;
-	for (i = 0; i < ELF_NVSRHALFREG ; i++)
-		task->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];
-	return 0;
-}
-#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
-#else
-inline unsigned long copy_fpr_to_user(void __user *to,
-				      struct task_struct *task)
-{
-	return __copy_to_user(to, task->thread.fp_state.fpr,
-			      ELF_NFPREG * sizeof(double));
-}
-
-inline unsigned long copy_fpr_from_user(struct task_struct *task,
-					void __user *from)
-{
-	return __copy_from_user(task->thread.fp_state.fpr, from,
-			      ELF_NFPREG * sizeof(double));
-}
-
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-inline unsigned long copy_ckfpr_to_user(void __user *to,
-					 struct task_struct *task)
-{
-	return __copy_to_user(to, task->thread.ckfp_state.fpr,
-			      ELF_NFPREG * sizeof(double));
-}
-
-inline unsigned long copy_ckfpr_from_user(struct task_struct *task,
-						 void __user *from)
-{
-	return __copy_from_user(task->thread.ckfp_state.fpr, from,
-				ELF_NFPREG * sizeof(double));
-}
-#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
-#endif
-
 /*
  * Save the current user registers on the user stack.
  * We only save the altivec/spe registers if the process has used
-- 
2.22.0

[PATCH v4 3/4] powerpc/64: make buildable without CONFIG_COMPAT

[Michal Suchanek]

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

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
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
 #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
 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);
 }
-- 
2.22.0

[PATCH v4 4/4] powerpc/64: Make COMPAT user-selectable disabled on littleendian by default.

[Michal Suchanek]

On bigendian ppc64 it is common to have 32bit legacy binaries but much
less so on littleendian.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
v3: make configurable
---
 arch/powerpc/Kconfig | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 5bab0bb6b833..b0339e892329 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -264,8 +264,9 @@ config PANIC_TIMEOUT
 	default 180
 
 config COMPAT
-	bool
-	default y if PPC64
+	bool "Enable support for 32bit binaries"
+	depends on PPC64
+	default y if !CPU_LITTLE_ENDIAN
 	select COMPAT_BINFMT_ELF
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT_OLD_SIGACTION
-- 
2.22.0

Re: [PATCH v4 3/4] powerpc/64: make buildable without CONFIG_COMPAT

[Michal Suchánek]

On Thu, 29 Aug 2019 12:23:42 +0200
Michal Suchanek <msuchanek@suse.de> wrote:

> There are numerous references to 32bit functions in generic and 64bit
> code so ifdef them out.
> 
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> ---
> 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
>  #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
>  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);
>  }

This will likely cause unreachable code on 32bit. Since there is need
for an ifdef and it cannot be inside condition the best is probably to
just split it to two separate conditions:

 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);
+#endif
 }

Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

[Arnd Bergmann]

On Thu, Aug 29, 2019 at 12:23 PM Michal Suchanek <msuchanek@suse.de> wrote:
>
> Fixes: aff850393200 ("powerpc: add system call table generation support")

This patch needs a proper explanation. The Fixes tag doesn't seem right
here, since ppc64 has had llseek since the start in 2002 commit 3939e37587e7
("Add ppc64 support. This includes both pSeries (RS/6000) and iSeries
(AS/400).").

> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
> index 010b9f445586..53e427606f6c 100644
> --- a/arch/powerpc/kernel/syscalls/syscall.tbl
> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
> @@ -188,7 +188,7 @@
>  137    common  afs_syscall                     sys_ni_syscall
>  138    common  setfsuid                        sys_setfsuid
>  139    common  setfsgid                        sys_setfsgid
> -140    common  _llseek                         sys_llseek
> +140    32      _llseek                         sys_llseek
>  141    common  getdents                        sys_getdents                    compat_sys_getdents
>  142    common  _newselect                      sys_select                      compat_sys_select
>  143    common  flock                           sys_flock

In particular, I don't see why you single out llseek here, but leave other
syscalls that are not needed on 64-bit machines such as pread64().

        ARnd

Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

[Michal Suchánek]

On Thu, 29 Aug 2019 14:19:46 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Thu, Aug 29, 2019 at 12:23 PM Michal Suchanek <msuchanek@suse.de> wrote:
> >
> > Fixes: aff850393200 ("powerpc: add system call table generation support")  
> 
> This patch needs a proper explanation. The Fixes tag doesn't seem right
> here, since ppc64 has had llseek since the start in 2002 commit 3939e37587e7
> ("Add ppc64 support. This includes both pSeries (RS/6000) and iSeries
> (AS/400).").
> 
> > diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
> > index 010b9f445586..53e427606f6c 100644
> > --- a/arch/powerpc/kernel/syscalls/syscall.tbl
> > +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
> > @@ -188,7 +188,7 @@
> >  137    common  afs_syscall                     sys_ni_syscall
> >  138    common  setfsuid                        sys_setfsuid
> >  139    common  setfsgid                        sys_setfsgid
> > -140    common  _llseek                         sys_llseek
> > +140    32      _llseek                         sys_llseek
> >  141    common  getdents                        sys_getdents                    compat_sys_getdents
> >  142    common  _newselect                      sys_select                      compat_sys_select
> >  143    common  flock                           sys_flock  
> 
> In particular, I don't see why you single out llseek here, but leave other
> syscalls that are not needed on 64-bit machines such as pread64().

Because llseek is not built in fs/ when building 64bit only causing a
link error. 

I initially posted patch to build it always but it was pointed out it
is not needed, and  the interface does not make sense on 64bit, and
that platforms that don't have it on 64bit now don't want that useless
code.

Thanks

Michal

Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

[Arnd Bergmann]

On Thu, Aug 29, 2019 at 2:37 PM Michal Suchánek <msuchanek@suse.de> wrote:
> On Thu, 29 Aug 2019 14:19:46 +0200 Arnd Bergmann <arnd@arndb.de> wrote:
> > On Thu, Aug 29, 2019 at 12:23 PM Michal Suchanek <msuchanek@suse.de> wrote:
> > In particular, I don't see why you single out llseek here, but leave other
> > syscalls that are not needed on 64-bit machines such as pread64().
>
> Because llseek is not built in fs/ when building 64bit only causing a
> link error.
>
> I initially posted patch to build it always but it was pointed out it
> is not needed, and  the interface does not make sense on 64bit, and
> that platforms that don't have it on 64bit now don't want that useless
> code.

Ok, please put that into the changeset description then.

I looked at uses of __NR__llseek in debian code search and
found this one:

https://codesearch.debian.net/show?file=umview_0.8.2-1.2%2Fxmview%2Fum_mmap.c&line=328

It looks like this application will try to use llseek instead of lseek
when built against kernel headers that define __NR_llseek.

Changing the powerpc kernel not to provide that to user
space may break it unless the program gets recompiled against
the latest headers.

      Arnd

Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

[Michal Suchánek]

On Thu, 29 Aug 2019 14:57:39 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Thu, Aug 29, 2019 at 2:37 PM Michal Suchánek <msuchanek@suse.de> wrote:
> > On Thu, 29 Aug 2019 14:19:46 +0200 Arnd Bergmann <arnd@arndb.de> wrote:  
> > > On Thu, Aug 29, 2019 at 12:23 PM Michal Suchanek <msuchanek@suse.de> wrote:
> > > In particular, I don't see why you single out llseek here, but leave other
> > > syscalls that are not needed on 64-bit machines such as pread64().  
> >
> > Because llseek is not built in fs/ when building 64bit only causing a
> > link error.
> >
> > I initially posted patch to build it always but it was pointed out it
> > is not needed, and  the interface does not make sense on 64bit, and
> > that platforms that don't have it on 64bit now don't want that useless
> > code.  
> 
> Ok, please put that into the changeset description then.
> 
> I looked at uses of __NR__llseek in debian code search and
> found this one:
> 
> https://codesearch.debian.net/show?file=umview_0.8.2-1.2%2Fxmview%2Fum_mmap.c&line=328
> 
> It looks like this application will try to use llseek instead of lseek
> when built against kernel headers that define __NR_llseek.
> 

The available documentation says this syscall is for 32bit only so
using it on 64bit is undefined. The interface is not well-defined in
that case either.

Thanks

Michal

Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

[Arnd Bergmann]

On Thu, Aug 29, 2019 at 4:19 PM Michal Suchánek <msuchanek@suse.de> wrote:
> On Thu, 29 Aug 2019 14:57:39 +0200 Arnd Bergmann <arnd@arndb.de> wrote:
> > On Thu, Aug 29, 2019 at 2:37 PM Michal Suchánek <msuchanek@suse.de> wrote:
> > > On Thu, 29 Aug 2019 14:19:46 +0200 Arnd Bergmann <arnd@arndb.de> wrote:
> > > > On Thu, Aug 29, 2019 at 12:23 PM Michal Suchanek <msuchanek@suse.de> wrote:
> > > > In particular, I don't see why you single out llseek here, but leave other
> > > > syscalls that are not needed on 64-bit machines such as pread64().
> > >
> > > Because llseek is not built in fs/ when building 64bit only causing a
> > > link error.
> > >
> > > I initially posted patch to build it always but it was pointed out it
> > > is not needed, and  the interface does not make sense on 64bit, and
> > > that platforms that don't have it on 64bit now don't want that useless
> > > code.
> >
> > Ok, please put that into the changeset description then.
> >
> > I looked at uses of __NR__llseek in debian code search and
> > found this one:
> >
> > https://codesearch.debian.net/show?file=umview_0.8.2-1.2%2Fxmview%2Fum_mmap.c&line=328
> >
> > It looks like this application will try to use llseek instead of lseek
> > when built against kernel headers that define __NR_llseek.
> >
>
> The available documentation says this syscall is for 32bit only so
> using it on 64bit is undefined. The interface is not well-defined in
> that case either.

That's generally not how it works. If there is an existing application
that relies on the behavior of the system call interface, we should not
change it in a way that breaks the application, regardless of what the
documentation says. Presumably nobody cares about umview on
powerpc64, but there might be other applications doing the same
thing.

It looks like sparc64 and parisc64 do the same thing as powerpc64,
and provide llseek() calls that may or may not be used by
applications.

I think your original approach of always building sys_llseek on
powerpc64 is the safe choice here.

     Arnd

Re: [PATCH v4 3/4] powerpc/64: make buildable without CONFIG_COMPAT

[Christophe Leroy]

Le 29/08/2019 à 12:23, 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>
> ---
> 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 ?

>   #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().

>   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 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()

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...

Christophe

Re: [PATCH v4 3/4] powerpc/64: make buildable without CONFIG_COMPAT

[Michal Suchánek]

On Thu, 29 Aug 2019 19:40:55 +0200
Christophe Leroy <christophe.leroy@c-s.fr> wrote:

> Le 29/08/2019 à 12:23, 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>
> > ---
> > 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.

> 
> >   #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.

> 
> >   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

Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

[Michal Suchánek]

On Thu, 29 Aug 2019 16:32:50 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Thu, Aug 29, 2019 at 4:19 PM Michal Suchánek <msuchanek@suse.de> wrote:
> > On Thu, 29 Aug 2019 14:57:39 +0200 Arnd Bergmann <arnd@arndb.de> wrote:  
> > > On Thu, Aug 29, 2019 at 2:37 PM Michal Suchánek <msuchanek@suse.de> wrote:  
> > > > On Thu, 29 Aug 2019 14:19:46 +0200 Arnd Bergmann <arnd@arndb.de> wrote:  
> > > > > On Thu, Aug 29, 2019 at 12:23 PM Michal Suchanek <msuchanek@suse.de> wrote:
> > > > > In particular, I don't see why you single out llseek here, but leave other
> > > > > syscalls that are not needed on 64-bit machines such as pread64().  
> > > >
> > > > Because llseek is not built in fs/ when building 64bit only causing a
> > > > link error.
> > > >
> > > > I initially posted patch to build it always but it was pointed out it
> > > > is not needed, and  the interface does not make sense on 64bit, and
> > > > that platforms that don't have it on 64bit now don't want that useless
> > > > code.  
> > >
> > > Ok, please put that into the changeset description then.
> > >
> > > I looked at uses of __NR__llseek in debian code search and
> > > found this one:
> > >
> > > https://codesearch.debian.net/show?file=umview_0.8.2-1.2%2Fxmview%2Fum_mmap.c&line=328
> > >
> > > It looks like this application will try to use llseek instead of lseek
> > > when built against kernel headers that define __NR_llseek.
> > >  
> >
> > The available documentation says this syscall is for 32bit only so
> > using it on 64bit is undefined. The interface is not well-defined in
> > that case either.  
> 
> That's generally not how it works. If there is an existing application
> that relies on the behavior of the system call interface, we should not
> change it in a way that breaks the application, regardless of what the
> documentation says. Presumably nobody cares about umview on
> powerpc64, but there might be other applications doing the same
> thing.

Actually the umview headers go out of their way to define the llseek
syscall as invalid on x86_64 so that the non-llseek path is taken. 
mview-os/xmview/defs_x86_64_um.h:#define __NR__llseek __NR_doesnotexist
It is probably an oversight that this is not done on non-x86. I am not
even sure this builds on non-x86 out of the box.

> It looks like sparc64 and parisc64 do the same thing as powerpc64,
> and provide llseek() calls that may or may not be used by
> applications.

And if they are supposed to build with !compat it should be removed
there as well.

> 
> I think your original approach of always building sys_llseek on
> powerpc64 is the safe choice here.

That's safe but adds junk to the kernel as pointed out in the reply to
that patch.

Thanks

Michal