Since the introduction of SECCOMP_RET_TRACE support, the kernel supports
simultaneously both the generic kernel -ERRORCODE return value ABI and
the powerpc sc syscall return ABI for PTRACE_EVENT_SECCOMP tracers.
This change is an attempt to address the code inconsistencies in syscall
error return handling that were introduced as a side effect of the dual
ABI support.

Signed-off-by: Dmitry V. Levin <redacted>
---
  arch/powerpc/kernel/ptrace/ptrace.c | 23 ++++++++++++++++++++---
  arch/powerpc/kernel/signal.c        | 11 +++--------
  arch/powerpc/kernel/syscall.c       |  6 +++---
  3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c
index 727ed4a14545..3778775bf6ba 100644
--- a/arch/powerpc/kernel/ptrace/ptrace.c
+++ b/arch/powerpc/kernel/ptrace/ptrace.c

@@ -207,7 +207,7 @@ static int do_seccomp(struct pt_regs *regs)
  	 * syscall parameter. This is different to the ptrace ABI where
  	 * both r3 and orig_gpr3 contain the first syscall parameter.
  	 */
-	regs->gpr[3] = -ENOSYS;
+	syscall_set_return_value(current, regs, -ENOSYS, 0);
  
  	/*
  	 * We use the __ version here because we have already checked

@@ -215,8 +215,18 @@ static int do_seccomp(struct pt_regs *regs)
  	 * have already loaded -ENOSYS into r3, or seccomp has put
  	 * something else in r3 (via SECCOMP_RET_ERRNO/TRACE).
  	 */
-	if (__secure_computing(NULL))
+	if (__secure_computing(NULL)) {
+
+		/*
+		 * Traditionally, both the generic kernel -ERRORCODE return
+		 * value ABI and the powerpc sc syscall return ABI is
+		 * supported.  For consistency, if the former is detected,
+		 * convert it to the latter.
+		 */
+		if (!trap_is_scv(regs) && IS_ERR_VALUE(regs->gpr[3]))

+			syscall_set_return_value(current, regs, regs->gpr[3], 0);
  		return -1;
+	}
  
  	/*
  	 * The syscall was allowed by seccomp, restore the register

@@ -226,6 +236,13 @@ static int do_seccomp(struct pt_regs *regs)
  	 * allow the syscall to proceed.
  	 */
  	regs->gpr[3] = regs->orig_gpr3;
+	if (!trap_is_scv(regs)) {
+		/*
+		 * Clear SO bit that was set in this function earlier by
+		 * syscall_set_return_value.
+		 */
+		regs->ccr &= ~0x10000000L;
+	}

  
  	return 0;
  }

@@ -315,7 +332,7 @@ long do_syscall_trace_enter(struct pt_regs *regs)
  	 * If we are aborting explicitly, or if the syscall number is
  	 * now invalid, set the return value to -ENOSYS.
  	 */
-	regs->gpr[3] = -ENOSYS;
+	syscall_set_return_value(current, regs, -ENOSYS, 0);
  	return -1;
  }
  

diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index aa17e62f3754..1a38d6bcaed6 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c

@@ -19,6 +19,7 @@
  #include <asm/unistd.h>
  #include <asm/debug.h>
  #include <asm/tm.h>
+#include <asm/syscall.h>
  
  #include "signal.h"
  

@@ -229,14 +230,8 @@ static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
  		regs_add_return_ip(regs, -4);
  		regs->result = 0;
  	} else {
-		if (trap_is_scv(regs)) {
-			regs->result = -EINTR;
-			regs->gpr[3] = -EINTR;
-		} else {
-			regs->result = -EINTR;
-			regs->gpr[3] = EINTR;
-			regs->ccr |= 0x10000000;
-		}
+		regs->result = -EINTR;
+		syscall_set_return_value(current, regs, -EINTR, 0);
  	}
  }
  

diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c
index be159ad4b77b..2fe47191e509 100644
--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c

@@ -122,7 +122,7 @@ notrace long system_call_exception(struct pt_regs *regs, unsigned long r0)
  		if (unlikely(trap_is_unsupported_scv(regs))) {
  			/* Unsupported scv vector */
  			_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
-			return regs->gpr[3];
+			return regs_return_value(regs);
  		}
  		/*
  		 * We use the return value of do_syscall_trace_enter() as the

@@ -133,13 +133,13 @@ notrace long system_call_exception(struct pt_regs *regs, unsigned long r0)
  		 */
  		r0 = do_syscall_trace_enter(regs);
  		if (unlikely(r0 >= NR_syscalls))
-			return regs->gpr[3];
+			return regs_return_value(regs);
  
  	} else if (unlikely(r0 >= NR_syscalls)) {
  		if (unlikely(trap_is_unsupported_scv(regs))) {
  			/* Unsupported scv vector */
  			_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
-			return regs->gpr[3];
+			return regs_return_value(regs);
  		}
  		return -ENOSYS;
  	}