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authorNicholas Piggin <npiggin@gmail.com>2020-07-08 17:49:42 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2020-07-15 12:02:20 +1000
commit1f9bb31e58118e14ab66239796f2fbe633e1ad32 (patch)
tree32ef96d7c2fd02413503e27e2e9edcefa0412c08 /tools/testing/selftests/powerpc/math
parentpowerpc/64/signal: Balance return predictor stack in signal trampoline (diff)
downloadlinux-dev-1f9bb31e58118e14ab66239796f2fbe633e1ad32.tar.xz
linux-dev-1f9bb31e58118e14ab66239796f2fbe633e1ad32.zip
selftests/powerpc: Add FPU denormal test
Add a testcase that tries to trigger the FPU denormal exception on Power8 or earlier CPUs. Prior to commit 4557ac6b344b ("powerpc/64s/exception: Fix 0x1500 interrupt handler crash") this would trigger a crash such as: Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: iptable_mangle xt_MASQUERADE iptable_nat nf_nat xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ipt_REJECT nf_reject_ipv4 xt_tcpudp tun bridge stp llc ip6table_filter ip6_tables iptable_filter fuse kvm_hv binfmt_misc squashfs mlx4_ib ib_uverbs dm_multipath scsi_dh_rdac scsi_dh_alua ib_core mlx4_en sr_mod cdrom bnx2x lpfc mlx4_core crc_t10dif scsi_transport_fc sg mdio vmx_crypto crct10dif_vpmsum leds_powernv powernv_rng rng_core led_class powernv_op_panel sunrpc ip_tables x_tables autofs4 CPU: 159 PID: 6854 Comm: fpu_denormal Not tainted 5.8.0-rc2-gcc-8.2.0-00092-g4ec7aaab0828 #192 NIP: c0000000000100ec LR: c00000000001b85c CTR: 0000000000000000 REGS: c000001dd818f770 TRAP: 1500 Not tainted (5.8.0-rc2-gcc-8.2.0-00092-g4ec7aaab0828) MSR: 900000000290b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24002884 XER: 20000000 CFAR: c00000000001005c IRQMASK: 1 GPR00: c00000000001c4c8 c000001dd818fa00 c00000000171c200 c000001dd8101570 GPR04: 0000000000000000 c000001dd818fe90 c000001dd8101590 000000000000001d GPR08: 0000000000000010 0000000000002000 c000001dd818fe90 fffffffffc48ac60 GPR12: 0000000000002200 c000001ffff4f480 0000000000000000 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 00007fffab225b40 0000000000000001 c000000001757168 GPR24: c000001dd8101570 c0000018027b00f0 c000001dd8101570 c000000001496098 GPR28: c00000000174ad05 c000001dd8100000 c000001dd8100000 c000001dd8100000 NIP save_fpu+0xa8/0x2ac LR __giveup_fpu+0x2c/0xd0 Call Trace: 0xc000001dd818fa80 (unreliable) giveup_all+0x118/0x120 __switch_to+0x124/0x6c0 __schedule+0x390/0xaf0 do_task_dead+0x70/0x80 do_exit+0x8fc/0xe10 do_group_exit+0x64/0xd0 sys_exit_group+0x24/0x30 system_call_exception+0x164/0x270 system_call_common+0xf0/0x278 Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Split out of fix patch, add oops log] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200708074942.1713396-1-npiggin@gmail.com
Diffstat (limited to 'tools/testing/selftests/powerpc/math')
-rw-r--r--tools/testing/selftests/powerpc/math/.gitignore1
-rw-r--r--tools/testing/selftests/powerpc/math/Makefile2
-rw-r--r--tools/testing/selftests/powerpc/math/fpu_denormal.c38
3 files changed, 40 insertions, 1 deletions
diff --git a/tools/testing/selftests/powerpc/math/.gitignore b/tools/testing/selftests/powerpc/math/.gitignore
index e31ca6f453ed..d0c23b2e4b60 100644
--- a/tools/testing/selftests/powerpc/math/.gitignore
+++ b/tools/testing/selftests/powerpc/math/.gitignore
@@ -6,3 +6,4 @@ vmx_preempt
fpu_signal
vmx_signal
vsx_preempt
+fpu_denormal
diff --git a/tools/testing/selftests/powerpc/math/Makefile b/tools/testing/selftests/powerpc/math/Makefile
index 11a10d7a2bbd..4e2049d2fd8d 100644
--- a/tools/testing/selftests/powerpc/math/Makefile
+++ b/tools/testing/selftests/powerpc/math/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
-TEST_GEN_PROGS := fpu_syscall fpu_preempt fpu_signal vmx_syscall vmx_preempt vmx_signal vsx_preempt
+TEST_GEN_PROGS := fpu_syscall fpu_preempt fpu_signal fpu_denormal vmx_syscall vmx_preempt vmx_signal vsx_preempt
top_srcdir = ../../../../..
include ../../lib.mk
diff --git a/tools/testing/selftests/powerpc/math/fpu_denormal.c b/tools/testing/selftests/powerpc/math/fpu_denormal.c
new file mode 100644
index 000000000000..5f96682abaa8
--- /dev/null
+++ b/tools/testing/selftests/powerpc/math/fpu_denormal.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright IBM Corp. 2020
+ *
+ * This test attempts to cause a FP denormal exception on POWER8 CPUs. Unfortunately
+ * if the denormal handler is not configured or working properly, this can cause a bad
+ * crash in kernel mode when the kernel tries to save FP registers when the process
+ * exits.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "utils.h"
+
+static int test_denormal_fpu(void)
+{
+ unsigned int m32;
+ unsigned long m64;
+ volatile float f;
+ volatile double d;
+
+ /* try to induce lfs <denormal> ; stfd */
+
+ m32 = 0x00715fcf; /* random denormal */
+ memcpy((float *)&f, &m32, sizeof(f));
+ d = f;
+ memcpy(&m64, (double *)&d, sizeof(d));
+
+ FAIL_IF((long)(m64 != 0x380c57f3c0000000)); /* renormalised value */
+
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ return test_harness(test_denormal_fpu, "fpu_denormal");
+}