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 <l...@strace.io>
---
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;
}
--
ldv
