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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, stable@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: [PATCH 18/19] s390: correct nospec auto detection init order
Date: Fri, 27 Apr 2018 07:36:56 +0200	[thread overview]
Message-ID: <20180427053657.56944-19-schwidefsky@de.ibm.com> (raw)
In-Reply-To: <20180427053657.56944-1-schwidefsky@de.ibm.com>

[ Upstream commit 6a3d1e81a434fc311f224b8be77258bafc18ccc6 ]

With CONFIG_EXPOLINE_AUTO=y the call of spectre_v2_auto_early() via
early_initcall is done *after* the early_param functions. This
overwrites any settings done with the nobp/no_spectre_v2/spectre_v2
parameters. The code patching for the kernel is done after the
evaluation of the early parameters but before the early_initcall
is done. The end result is a kernel image that is patched correctly
but the kernel modules are not.

Make sure that the nospec auto detection function is called before the
early parameters are evaluated and before the code patching is done.

Fixes: 6e179d64126b ("s390: add automatic detection of the spectre defense")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/include/asm/nospec-branch.h | 1 +
 arch/s390/kernel/nospec-branch.c      | 8 ++------
 arch/s390/kernel/setup.c              | 3 +++
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/s390/include/asm/nospec-branch.h b/arch/s390/include/asm/nospec-branch.h
index 35bf28fe4c64..b4bd8c41e9d3 100644
--- a/arch/s390/include/asm/nospec-branch.h
+++ b/arch/s390/include/asm/nospec-branch.h
@@ -9,6 +9,7 @@
 extern int nospec_disable;
 
 void nospec_init_branches(void);
+void nospec_auto_detect(void);
 void nospec_revert(s32 *start, s32 *end);
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c
index 73c06d42792d..9f3b5b382743 100644
--- a/arch/s390/kernel/nospec-branch.c
+++ b/arch/s390/kernel/nospec-branch.c
@@ -73,7 +73,7 @@ static int __init nospectre_v2_setup_early(char *str)
 }
 early_param("nospectre_v2", nospectre_v2_setup_early);
 
-static int __init spectre_v2_auto_early(void)
+void __init nospec_auto_detect(void)
 {
 	if (IS_ENABLED(CC_USING_EXPOLINE)) {
 		/*
@@ -88,11 +88,7 @@ static int __init spectre_v2_auto_early(void)
 	 * 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)
 {
@@ -103,7 +99,7 @@ static int __init spectre_v2_setup_early(char *str)
 	if (str && !strncmp(str, "off", 3))
 		nospec_disable = 1;
 	if (str && !strncmp(str, "auto", 4))
-		spectre_v2_auto_early();
+		nospec_auto_detect();
 	return 0;
 }
 early_param("spectre_v2", spectre_v2_setup_early);
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index bc25366f0244..feb9d97a9d14 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -876,6 +876,9 @@ void __init setup_arch(char **cmdline_p)
 	init_mm.end_data = (unsigned long) &_edata;
 	init_mm.brk = (unsigned long) &_end;
 
+	if (IS_ENABLED(CONFIG_EXPOLINE_AUTO))
+		nospec_auto_detect();
+
 	parse_early_param();
 #ifdef CONFIG_CRASH_DUMP
 	/* Deactivate elfcorehdr= kernel parameter */
-- 
2.13.5

  parent reply	other threads:[~2018-04-27  5:37 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-27  5:36 [PATCH 00/19] s390 spectre mititgation for 4.9 Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 01/19] s390: introduce CPU alternatives Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 02/19] s390: enable CPU alternatives unconditionally Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 03/19] KVM: s390: wire up bpb feature Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 04/19] s390: scrub registers on kernel entry and KVM exit Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 05/19] s390: add optimized array_index_mask_nospec Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 06/19] s390/alternative: use a copy of the facility bit mask Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 07/19] s390: add options to change branch prediction behaviour for the kernel Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 08/19] s390: run user space and KVM guests with modified branch prediction Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 09/19] s390: introduce execute-trampolines for branches Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 10/19] KVM: s390: force bp isolation for VSIE Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 11/19] s390: Replace IS_ENABLED(EXPOLINE_*) with IS_ENABLED(CONFIG_EXPOLINE_*) Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 12/19] s390: do not bypass BPENTER for interrupt system calls Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 13/19] s390/entry.S: fix spurious zeroing of r0 Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 14/19] s390: move nobp parameter functions to nospec-branch.c Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 15/19] s390: add automatic detection of the spectre defense Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 16/19] s390: report spectre mitigation via syslog Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 17/19] s390: add sysfs attributes for spectre Martin Schwidefsky
2018-04-27  5:36 ` Martin Schwidefsky [this message]
2018-04-27  5:36 ` [PATCH 19/19] s390: correct module section names for expoline code revert Martin Schwidefsky
2018-04-27 10:11 ` [PATCH 00/19] s390 spectre mititgation for 4.9 Greg Kroah-Hartman
  -- strict thread matches above, loose matches on Subject: below --
2018-04-27  5:36 [PATCH 00/19] s390 spectre mititgation for 4.14 Martin Schwidefsky
2018-04-27  5:36 ` [PATCH 18/19] s390: correct nospec auto detection init order Martin Schwidefsky

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