pseries: Add H_SET_MODE to change exception endianness

On little endian builds call H_SET_MODE so exceptions have the
correct endianness. We need to reset the endian during kexec
so do that in the MMU hashtable clear callback.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index 0c7f2bfcf1348100fb10c4cd6f74dcee34e42756..d8b600b3f058bda7e0358931b885b8c5d4f30215 100644 (file)
--- 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/include/asm/plpar_wrappers.h b/arch/powerpc/include/asm/plpar_wrappers.h
index a63b045e707ce8a5d34c91e8fa698808a8ee4647..12c32c5f533d924428714301f7482493df00e3c8 100644 (file)
--- a/arch/powerpc/include/asm/plpar_wrappers.h
+++ b/arch/powerpc/include/asm/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/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 356bc75ca74f6f0bf8f08dd6eca37b5c538dbfc3..4fca3def9db951896864d0b716d7dea8a2364ba2 100644 (file)
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -245,6 +245,23 @@ 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/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 1f97e2b87a62b85d30bf848a8dbab31938304f21..c1f1908587011d6d131dd56bdf2e1cb283c41128 100644 (file)
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -442,6 +442,32 @@ 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;
@@ -698,6 +724,22 @@ 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