On little endian builds call H_SET_MODE so exceptions have the
correct endianness. We need a better hook to handle flipping back
into big endian mode on a kexec, but insert it into the mmu
teardown callback for now.
Signed-off-by: Anton Blanchard <an...@samba.org>
---
arch/powerpc/include/asm/hvcall.h | 2 ++
arch/powerpc/platforms/pseries/lpar.c | 17 ++++++++++
arch/powerpc/platforms/pseries/plpar_wrappers.h | 26 +++++++++++++++
arch/powerpc/platforms/pseries/setup.c | 42 +++++++++++++++++++++++++
4 files changed, 87 insertions(+)
diff --git a/arch/powerpc/include/asm/hvcall.h
b/arch/powerpc/include/asm/hvcall.h
index 0c7f2bf..d8b600b 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -403,6 +403,8 @@ static inline unsigned long cmo_get_page_size(void)
extern long pSeries_enable_reloc_on_exc(void);
extern long pSeries_disable_reloc_on_exc(void);
+extern long pseries_big_endian_exceptions(void);
+
#else
#define pSeries_enable_reloc_on_exc() do {} while (0)
diff --git a/arch/powerpc/platforms/pseries/lpar.c
b/arch/powerpc/platforms/pseries/lpar.c
index 0b7c86e..f28bf35 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -239,6 +239,23 @@ static void pSeries_lpar_hptab_clear(void)
&(ptes[j].pteh), &(ptes[j].ptel));
}
}
+
+#ifdef __LITTLE_ENDIAN__
+ /* Reset exceptions to big endian */
+ if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
+ long rc;
+
+ rc = pseries_big_endian_exceptions();
+ /*
+ * At this point it is unlikely panic() will get anything
+ * out to the user, but at least this will stop us from
+ * continuing on further and creating an even more
+ * difficult to debug situation.
+ */
+ if (rc)
+ panic("Could not enable big endian exceptions");
+ }
+#endif
}
/*
diff --git a/arch/powerpc/platforms/pseries/plpar_wrappers.h
b/arch/powerpc/platforms/pseries/plpar_wrappers.h
index 417d0bf..6c1c218 100644
--- a/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ b/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -287,6 +287,32 @@ static inline long disable_reloc_on_exceptions(void) {
return plpar_set_mode(0, 3, 0, 0);
}
+/*
+ * Take exceptions in big endian mode on this partition
+ *
+ * Note: this call has a partition wide scope and can take a while to complete.
+ * If it returns H_LONG_BUSY_* it should be retried periodically until it
+ * returns H_SUCCESS.
+ */
+static inline long enable_big_endian_exceptions(void)
+{
+ /* mflags = 0: big endian exceptions */
+ return plpar_set_mode(0, 4, 0, 0);
+}
+
+/*
+ * Take exceptions in little endian mode on this partition
+ *
+ * Note: this call has a partition wide scope and can take a while to complete.
+ * If it returns H_LONG_BUSY_* it should be retried periodically until it
+ * returns H_SUCCESS.
+ */
+static inline long enable_little_endian_exceptions(void)
+{
+ /* mflags = 1: little endian exceptions */
+ return plpar_set_mode(1, 4, 0, 0);
+}
+
static inline long plapr_set_ciabr(unsigned long ciabr)
{
return plpar_set_mode(0, 1, ciabr, 0);
diff --git a/arch/powerpc/platforms/pseries/setup.c
b/arch/powerpc/platforms/pseries/setup.c
index 33d6196..51c195d 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -430,6 +430,32 @@ static void pSeries_machine_kexec(struct kimage *image)
}
#endif
+#ifdef __LITTLE_ENDIAN__
+long pseries_big_endian_exceptions(void)
+{
+ long rc;
+
+ while (1) {
+ rc = enable_big_endian_exceptions();
+ if (!H_IS_LONG_BUSY(rc))
+ return rc;
+ mdelay(get_longbusy_msecs(rc));
+ }
+}
+
+static long pseries_little_endian_exceptions(void)
+{
+ long rc;
+
+ while (1) {
+ rc = enable_little_endian_exceptions();
+ if (!H_IS_LONG_BUSY(rc))
+ return rc;
+ mdelay(get_longbusy_msecs(rc));
+ }
+}
+#endif
+
static void __init pSeries_setup_arch(void)
{
panic_timeout = 10;
@@ -687,6 +713,22 @@ static int __init pSeries_probe(void)
/* Now try to figure out if we are running on LPAR */
of_scan_flat_dt(pseries_probe_fw_features, NULL);
+#ifdef __LITTLE_ENDIAN__
+ if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
+ long rc;
+ /*
+ * Tell the hypervisor that we want our exceptions to
+ * be taken in little endian mode. If this fails we don't
+ * want to use BUG() because it will trigger an exception.
+ */
+ rc = pseries_little_endian_exceptions();
+ if (rc) {
+ ppc_md.progress("H_SET_MODE LE exception fail", 0);
+ panic("Could not enable little endian exceptions");
+ }
+ }
+#endif
+
if (firmware_has_feature(FW_FEATURE_LPAR))
hpte_init_lpar();
else
--
1.8.1.2
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