selftests/seccomp: powerpc: Fix seccomp return value testing

[ Upstream commit 46138329faeac3598f5a4dc991a174386b6de833 ]

On powerpc, the errno is not inverted, and depends on ccr.so being
set. Add this to a powerpc definition of SYSCALL_RET_SET().

Co-developed-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Link: https://lore.kernel.org/linux-kselftest/20200911181012.171027-1-cascardo@canonical.com/
Fixes: 5d83c2b37d43 ("selftests/seccomp: Add powerpc support")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/lkml/20200912110820.597135-13-keescook@chromium.org
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index e2f38507a0621ba3089fe67b44d8654fc125cbcf..9a9eb02539fb478e9e1e51550cead792741ac361 100644 (file)
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -1702,6 +1702,21 @@ TEST_F(TRACE_poke, getpid_runs_normally)
 # define ARCH_REGS             struct pt_regs
 # define SYSCALL_NUM(_regs)    (_regs).gpr[0]
 # define SYSCALL_RET(_regs)    (_regs).gpr[3]
+# define SYSCALL_RET_SET(_regs, _val)                          \
+       do {                                                    \
+               typeof(_val) _result = (_val);                  \
+               /*                                              \
+                * A syscall error is signaled by CR0 SO bit    \
+                * and the code is stored as a positive value.  \
+                */                                             \
+               if (_result < 0) {                              \
+                       SYSCALL_RET(_regs) = -result;           \
+                       (_regs).ccr |= 0x10000000;              \
+               } else {                                        \
+                       SYSCALL_RET(_regs) = result;            \
+                       (_regs).ccr &= ~0x10000000;             \
+               }                                               \
+       } while (0)
 #elif defined(__s390__)
 # define ARCH_REGS             s390_regs
 # define SYSCALL_NUM(_regs)    (_regs).gprs[2]