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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: [PATCH 4.9 42/74] s390: add automatic detection of the spectre defense
Date: Fri, 27 Apr 2018 15:58:32 +0200	[thread overview]
Message-ID: <20180427135711.670389532@linuxfoundation.org> (raw)
In-Reply-To: <20180427135709.899303463@linuxfoundation.org>

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Schwidefsky <schwidefsky@de.ibm.com>


[ Upstream commit 6e179d64126b909f0b288fa63cdbf07c531e9b1d ]

Automatically decide between nobp vs. expolines if the spectre_v2=auto
kernel parameter is specified or CONFIG_EXPOLINE_AUTO=y is set.

The decision made at boot time due to CONFIG_EXPOLINE_AUTO=y being set
can be overruled with the nobp, nospec and spectre_v2 kernel parameters.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/s390/Kconfig                     |    2 -
 arch/s390/Makefile                    |    2 -
 arch/s390/include/asm/nospec-branch.h |    6 +--
 arch/s390/kernel/alternative.c        |    1 
 arch/s390/kernel/module.c             |   11 ++---
 arch/s390/kernel/nospec-branch.c      |   68 +++++++++++++++++++++-------------
 6 files changed, 52 insertions(+), 38 deletions(-)

--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -741,7 +741,7 @@ choice
 config EXPOLINE_OFF
 	bool "spectre_v2=off"
 
-config EXPOLINE_MEDIUM
+config EXPOLINE_AUTO
 	bool "spectre_v2=auto"
 
 config EXPOLINE_FULL
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -85,7 +85,7 @@ ifdef CONFIG_EXPOLINE
     CC_FLAGS_EXPOLINE += -mfunction-return=thunk
     CC_FLAGS_EXPOLINE += -mindirect-branch-table
     export CC_FLAGS_EXPOLINE
-    cflags-y += $(CC_FLAGS_EXPOLINE)
+    cflags-y += $(CC_FLAGS_EXPOLINE) -DCC_USING_EXPOLINE
   endif
 endif
 
--- a/arch/s390/include/asm/nospec-branch.h
+++ b/arch/s390/include/asm/nospec-branch.h
@@ -6,12 +6,10 @@
 
 #include <linux/types.h>
 
-extern int nospec_call_disable;
-extern int nospec_return_disable;
+extern int nospec_disable;
 
 void nospec_init_branches(void);
-void nospec_call_revert(s32 *start, s32 *end);
-void nospec_return_revert(s32 *start, s32 *end);
+void nospec_revert(s32 *start, s32 *end);
 
 #endif /* __ASSEMBLY__ */
 
--- a/arch/s390/kernel/alternative.c
+++ b/arch/s390/kernel/alternative.c
@@ -1,6 +1,7 @@
 #include <linux/module.h>
 #include <asm/alternative.h>
 #include <asm/facility.h>
+#include <asm/nospec-branch.h>
 
 #define MAX_PATCH_LEN (255 - 1)
 
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -171,7 +171,7 @@ int module_frob_arch_sections(Elf_Ehdr *
 	me->core_layout.size += me->arch.got_size;
 	me->arch.plt_offset = me->core_layout.size;
 	if (me->arch.plt_size) {
-		if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_call_disable)
+		if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
 			me->arch.plt_size += PLT_ENTRY_SIZE;
 		me->core_layout.size += me->arch.plt_size;
 	}
@@ -330,8 +330,7 @@ static int apply_rela(Elf_Rela *rela, El
 				info->plt_offset;
 			ip[0] = 0x0d10e310;	/* basr 1,0  */
 			ip[1] = 0x100a0004;	/* lg	1,10(1) */
-			if (IS_ENABLED(CONFIG_EXPOLINE) &&
-			    !nospec_call_disable) {
+			if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
 				unsigned int *ij;
 				ij = me->core_layout.base +
 					me->arch.plt_offset +
@@ -452,7 +451,7 @@ int module_finalize(const Elf_Ehdr *hdr,
 	void *aseg;
 
 	if (IS_ENABLED(CONFIG_EXPOLINE) &&
-	    !nospec_call_disable && me->arch.plt_size) {
+	    !nospec_disable && me->arch.plt_size) {
 		unsigned int *ij;
 
 		ij = me->core_layout.base + me->arch.plt_offset +
@@ -479,11 +478,11 @@ int module_finalize(const Elf_Ehdr *hdr,
 
 		if (IS_ENABLED(CONFIG_EXPOLINE) &&
 		    (!strcmp(".nospec_call_table", secname)))
-			nospec_call_revert(aseg, aseg + s->sh_size);
+			nospec_revert(aseg, aseg + s->sh_size);
 
 		if (IS_ENABLED(CONFIG_EXPOLINE) &&
 		    (!strcmp(".nospec_return_table", secname)))
-			nospec_return_revert(aseg, aseg + s->sh_size);
+			nospec_revert(aseg, aseg + s->sh_size);
 	}
 
 	jump_label_apply_nops(me);
--- a/arch/s390/kernel/nospec-branch.c
+++ b/arch/s390/kernel/nospec-branch.c
@@ -11,10 +11,17 @@ static int __init nobp_setup_early(char
 	rc = kstrtobool(str, &enabled);
 	if (rc)
 		return rc;
-	if (enabled && test_facility(82))
+	if (enabled && test_facility(82)) {
+		/*
+		 * The user explicitely requested nobp=1, enable it and
+		 * disable the expoline support.
+		 */
 		__set_facility(82, S390_lowcore.alt_stfle_fac_list);
-	else
+		if (IS_ENABLED(CONFIG_EXPOLINE))
+			nospec_disable = 1;
+	} else {
 		__clear_facility(82, S390_lowcore.alt_stfle_fac_list);
+	}
 	return 0;
 }
 early_param("nobp", nobp_setup_early);
@@ -28,31 +35,46 @@ early_param("nospec", nospec_setup_early
 
 #ifdef CONFIG_EXPOLINE
 
-int nospec_call_disable = IS_ENABLED(CONFIG_EXPOLINE_OFF);
-int nospec_return_disable = !IS_ENABLED(CONFIG_EXPOLINE_FULL);
+int nospec_disable = IS_ENABLED(CONFIG_EXPOLINE_OFF);
 
 static int __init nospectre_v2_setup_early(char *str)
 {
-	nospec_call_disable = 1;
-	nospec_return_disable = 1;
+	nospec_disable = 1;
 	return 0;
 }
 early_param("nospectre_v2", nospectre_v2_setup_early);
 
+static int __init spectre_v2_auto_early(void)
+{
+	if (IS_ENABLED(CC_USING_EXPOLINE)) {
+		/*
+		 * The kernel has been compiled with expolines.
+		 * Keep expolines enabled and disable nobp.
+		 */
+		nospec_disable = 0;
+		__clear_facility(82, S390_lowcore.alt_stfle_fac_list);
+	}
+	/*
+	 * If the kernel has not been compiled with expolines the
+	 * nobp setting decides what is done, this depends on the
+	 * CONFIG_KERNEL_NP option and the nobp/nospec parameters.
+	 */
+	return 0;
+}
+#ifdef CONFIG_EXPOLINE_AUTO
+early_initcall(spectre_v2_auto_early);
+#endif
+
 static int __init spectre_v2_setup_early(char *str)
 {
 	if (str && !strncmp(str, "on", 2)) {
-		nospec_call_disable = 0;
-		nospec_return_disable = 0;
-	}
-	if (str && !strncmp(str, "off", 3)) {
-		nospec_call_disable = 1;
-		nospec_return_disable = 1;
-	}
-	if (str && !strncmp(str, "auto", 4)) {
-		nospec_call_disable = 0;
-		nospec_return_disable = 1;
+		nospec_disable = 0;
+		__clear_facility(82, S390_lowcore.alt_stfle_fac_list);
 	}
+	if (str && !strncmp(str, "off", 3))
+		nospec_disable = 1;
+	if (str && !strncmp(str, "auto", 4))
+		spectre_v2_auto_early();
 	return 0;
 }
 early_param("spectre_v2", spectre_v2_setup_early);
@@ -105,15 +127,9 @@ static void __init_or_module __nospec_re
 	}
 }
 
-void __init_or_module nospec_call_revert(s32 *start, s32 *end)
-{
-	if (nospec_call_disable)
-		__nospec_revert(start, end);
-}
-
-void __init_or_module nospec_return_revert(s32 *start, s32 *end)
+void __init_or_module nospec_revert(s32 *start, s32 *end)
 {
-	if (nospec_return_disable)
+	if (nospec_disable)
 		__nospec_revert(start, end);
 }
 
@@ -121,8 +137,8 @@ extern s32 __nospec_call_start[], __nosp
 extern s32 __nospec_return_start[], __nospec_return_end[];
 void __init nospec_init_branches(void)
 {
-	nospec_call_revert(__nospec_call_start, __nospec_call_end);
-	nospec_return_revert(__nospec_return_start, __nospec_return_end);
+	nospec_revert(__nospec_call_start, __nospec_call_end);
+	nospec_revert(__nospec_return_start, __nospec_return_end);
 }
 
 #endif /* CONFIG_EXPOLINE */

  parent reply	other threads:[~2018-04-27 13:58 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-27 13:57 [PATCH 4.9 00/74] 4.9.97-stable review Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 01/74] cifs: do not allow creating sockets except with SMB1 posix exensions Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 02/74] x86/tsc: Prevent 32bit truncation in calc_hpet_ref() Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 03/74] drm/vc4: Fix memory leak during BO teardown Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 04/74] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 05/74] i2c: i801: store and restore the SLVCMD register at load and unload Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 06/74] i2c: i801: Save register SMBSLVCMD value only once Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 07/74] i2c: i801: Restore configuration at shutdown Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 08/74] usb: musb: fix enumeration after resume Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 09/74] usb: musb: call pm_runtime_{get,put}_sync before reading vbus registers Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 10/74] usb: musb: Fix external abort in musb_remove on omap2430 Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 11/74] MIPS: Generic: Fix big endian CPUs on generic machine Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 12/74] Input: drv260x - fix initializing overdrive voltage Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 13/74] power: supply: bq2415x: check for NULL acpi_id to avoid null pointer dereference Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 14/74] [media] stk-webcam: fix an endian bug in stk_camera_read_reg() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 15/74] OF: Prevent unaligned access in of_alias_scan() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 16/74] ath9k_hw: check if the chip failed to wake up Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 17/74] jbd2: fix use after free in kjournald2() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 18/74] Revert "perf tools: Decompress kernel module when reading DSO data" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 19/74] perf: Fix sample_max_stack maximum check Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 20/74] perf: Return proper values for user stack errors Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 21/74] RDMA/mlx5: Fix NULL dereference while accessing XRC_TGT QPs Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 22/74] drm/i915/bxt, glk: Increase PCODE timeouts during CDCLK freq changing Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 23/74] mac80211_hwsim: fix use-after-free bug in hwsim_exit_net Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 24/74] r8152: add Linksys USB3GIGV1 id Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 25/74] Revert "pinctrl: intel: Initialize GPIO properly when used through irqchip" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 26/74] Revert "ath10k: send (re)assoc peer command when NSS changed" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 27/74] PCI: Wait up to 60 seconds for device to become ready after FLR Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 28/74] s390: introduce CPU alternatives Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 29/74] s390: enable CPU alternatives unconditionally Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 30/74] KVM: s390: wire up bpb feature Greg Kroah-Hartman
2018-04-27 15:43   ` Christian Borntraeger
2018-04-27 13:58 ` [PATCH 4.9 31/74] s390: scrub registers on kernel entry and KVM exit Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 32/74] s390: add optimized array_index_mask_nospec Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 33/74] s390/alternative: use a copy of the facility bit mask Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 34/74] s390: add options to change branch prediction behaviour for the kernel Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 35/74] s390: run user space and KVM guests with modified branch prediction Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 36/74] s390: introduce execute-trampolines for branches Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 37/74] KVM: s390: force bp isolation for VSIE Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 38/74] s390: Replace IS_ENABLED(EXPOLINE_*) with IS_ENABLED(CONFIG_EXPOLINE_*) Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 39/74] s390: do not bypass BPENTER for interrupt system calls Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 40/74] s390/entry.S: fix spurious zeroing of r0 Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 41/74] s390: move nobp parameter functions to nospec-branch.c Greg Kroah-Hartman
2018-04-27 13:58 ` Greg Kroah-Hartman [this message]
2018-04-27 13:58 ` [PATCH 4.9 43/74] s390: report spectre mitigation via syslog Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 44/74] s390: add sysfs attributes for spectre Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 45/74] s390: correct nospec auto detection init order Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 46/74] s390: correct module section names for expoline code revert Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 47/74] bonding: do not set slave_dev npinfo before slave_enable_netpoll in bond_enslave Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 48/74] KEYS: DNS: limit the length of option strings Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 49/74] l2tp: check sockaddr length in pppol2tp_connect() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 50/74] net: validate attribute sizes in neigh_dump_table() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 51/74] llc: delete timers synchronously in llc_sk_free() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 52/74] tcp: dont read out-of-bounds opsize Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 53/74] team: avoid adding twice the same option to the event list Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 54/74] team: fix netconsole setup over team Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 55/74] packet: fix bitfield update race Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 56/74] tipc: add policy for TIPC_NLA_NET_ADDR Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 57/74] pppoe: check sockaddr length in pppoe_connect() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 58/74] vlan: Fix reading memory beyond skb->tail in skb_vlan_tagged_multi Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 59/74] sctp: do not check port in sctp_inet6_cmp_addr Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 60/74] net: sched: ife: signal not finding metaid Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 61/74] llc: hold llc_sap before release_sock() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 62/74] llc: fix NULL pointer deref for SOCK_ZAPPED Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 63/74] net: ethernet: ti: cpsw: fix tx vlan priority mapping Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 64/74] net: fix deadlock while clearing neighbor proxy table Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 65/74] tcp: md5: reject TCP_MD5SIG or TCP_MD5SIG_EXT on established sockets Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 66/74] net: af_packet: fix race in PACKET_{R|T}X_RING Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 67/74] ipv6: add RTA_TABLE and RTA_PREFSRC to rtm_ipv6_policy Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 68/74] strparser: Fix incorrect strp->need_bytes value Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 69/74] scsi: mptsas: Disable WRITE SAME Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 70/74] cdrom: information leak in cdrom_ioctl_media_changed() Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 71/74] s390/cio: update chpid descriptor after resource accessibility event Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 72/74] s390/dasd: fix IO error for newly defined devices Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 73/74] s390/uprobes: implement arch_uretprobe_is_alive() Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 74/74] ACPI / video: Only default only_lcd to true on Win8-ready _desktops_ Greg Kroah-Hartman
2018-04-27 18:13 ` [PATCH 4.9 00/74] 4.9.97-stable review Shuah Khan
2018-04-27 20:33 ` Dan Rue
2018-04-27 20:44 ` kernelci.org bot
2018-04-28 14:26 ` Guenter Roeck

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