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From: Tom Lendacky <thomas.lendacky@amd.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH] x86/mm/sme: Disable stack protection for mem_encrypt_identity.c
Date: Mon, 26 Feb 2018 17:25:54 -0600	[thread overview]
Message-ID: <20180226232554.14108.16881.stgit@tlendack-t1.amdoffice.net> (raw)

Stack protection is not compatible with early boot code.  All of the early
SME boot code is now isolated in a separate file, mem_encrypt_identity.c,
so arch/x86/mm/Makefile can be updated to turn off stack protection for
the entire file.  This eliminates the need to worry about other functions
within the file being instrumented with stack protection (as was seen
when a newer version of GCC instrumented sme_encrypt_kernel() where an
older version hadn't).  It also allows removal of the __nostackprotector
attribute from individual functions.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/mm/Makefile               |    1 +
 arch/x86/mm/mem_encrypt_identity.c |    4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 03c6c85..4b101dd 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -19,6 +19,7 @@ obj-y	:=  init.o init_$(BITS).o fault.o ioremap.o extable.o pageattr.o mmap.o \
 nostackp := $(call cc-option, -fno-stack-protector)
 CFLAGS_physaddr.o		:= $(nostackp)
 CFLAGS_setup_nx.o		:= $(nostackp)
+CFLAGS_mem_encrypt_identity.o	:= $(nostackp)
 
 CFLAGS_fault.o := -I$(src)/../include/asm/trace
 
diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index b4139c5..1b2197d 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -266,7 +266,7 @@ static unsigned long __init sme_pgtable_calc(unsigned long len)
 	return entries + tables;
 }
 
-void __init __nostackprotector sme_encrypt_kernel(struct boot_params *bp)
+void __init sme_encrypt_kernel(struct boot_params *bp)
 {
 	unsigned long workarea_start, workarea_end, workarea_len;
 	unsigned long execute_start, execute_end, execute_len;
@@ -468,7 +468,7 @@ void __init __nostackprotector sme_encrypt_kernel(struct boot_params *bp)
 	native_write_cr3(__native_read_cr3());
 }
 
-void __init __nostackprotector sme_enable(struct boot_params *bp)
+void __init sme_enable(struct boot_params *bp)
 {
 	const char *cmdline_ptr, *cmdline_arg, *cmdline_on, *cmdline_off;
 	unsigned int eax, ebx, ecx, edx;

             reply	other threads:[~2018-02-26 23:26 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-26 23:25 Tom Lendacky [this message]
2018-02-27  9:28 ` [PATCH] x86/mm/sme: Disable stack protection for mem_encrypt_identity.c Borislav Petkov
2018-02-27 15:43 ` Kirill A. Shutemov
2018-02-28 14:06 ` [tip:x86/apic] x86/apic: Move pending intr check code into it's own function tip-bot for Dou Liyang
2018-02-28 14:07 ` [tip:x86/apic] x86/apic: Replace common tools with new ones tip-bot for Dou Liyang
2018-02-28 14:27 ` [tip:x86/mm] x86/mm/sme: Disable stack protection for mem_encrypt_identity.c tip-bot for Tom Lendacky

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