[gentoo-commits] proj/linux-patches:4.19 commit in: /

["Mike Pagano" <mpagano@gentoo.org>]

commit:     f342d08590afb25979bde4bf6cde10542a9f27e7
Author:     Mike Pagano <mpagano <AT> gentoo <DOT> org>
AuthorDate: Wed May 20 11:29:45 2020 +0000
Commit:     Mike Pagano <mpagano <AT> gentoo <DOT> org>
CommitDate: Wed May 20 11:29:45 2020 +0000
URL:        https://gitweb.gentoo.org/proj/linux-patches.git/commit/?id=f342d085

Remove redundant patch: x86: Fix early boot crash on gcc-10

Signed-off-by: Mike Pagano <mpagano <AT> gentoo.org>

 0000_README                                |   4 -
 1700_x86-gcc-10-early-boot-crash-fix.patch | 131 -----------------------------
 2 files changed, 135 deletions(-)

diff --git a/0000_README b/0000_README
index 4cf06a4..63f9a11 100644
--- a/0000_README
+++ b/0000_README
@@ -543,10 +543,6 @@ Patch:  1510_fs-enable-link-security-restrictions-by-default.patch
 From:   http://sources.debian.net/src/linux/3.16.7-ckt4-3/debian/patches/debian/fs-enable-link-security-restrictions-by-default.patch/
 Desc:   Enable link security restrictions by default.
 
-Patch:  1700_x86-gcc-10-early-boot-crash-fix.patch
-From:   https://https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/patch/?id=f670269a42bfdd2c83a1118cc3d1b475547eac22
-Desc:   x86: Fix early boot crash on gcc-10
-
 Patch:  2000_BT-Check-key-sizes-only-if-Secure-Simple-Pairing-enabled.patch
 From:   https://lore.kernel.org/linux-bluetooth/20190522070540.48895-1-marcel@holtmann.org/raw
 Desc:   Bluetooth: Check key sizes only when Secure Simple Pairing is enabled. See bug #686758

diff --git a/1700_x86-gcc-10-early-boot-crash-fix.patch b/1700_x86-gcc-10-early-boot-crash-fix.patch
deleted file mode 100644
index 8cdf651..0000000
--- a/1700_x86-gcc-10-early-boot-crash-fix.patch
+++ /dev/null
@@ -1,131 +0,0 @@
-From f670269a42bfdd2c83a1118cc3d1b475547eac22 Mon Sep 17 00:00:00 2001
-From: Borislav Petkov <bp@suse.de>
-Date: Wed, 22 Apr 2020 18:11:30 +0200
-Subject: x86: Fix early boot crash on gcc-10, next try
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-... or the odyssey of trying to disable the stack protector for the
-function which generates the stack canary value.
-
-The whole story started with Sergei reporting a boot crash with a kernel
-built with gcc-10:
-
-  Kernel panic — not syncing: stack-protector: Kernel stack is corrupted in: start_secondary
-  CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc5—00235—gfffb08b37df9 #139
-  Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./H77M—D3H, BIOS F12 11/14/2013
-  Call Trace:
-    dump_stack
-    panic
-    ? start_secondary
-    __stack_chk_fail
-    start_secondary
-    secondary_startup_64
-  -—-[ end Kernel panic — not syncing: stack—protector: Kernel stack is corrupted in: start_secondary
-
-This happens because gcc-10 tail-call optimizes the last function call
-in start_secondary() - cpu_startup_entry() - and thus emits a stack
-canary check which fails because the canary value changes after the
-boot_init_stack_canary() call.
-
-To fix that, the initial attempt was to mark the one function which
-generates the stack canary with:
-
-  __attribute__((optimize("-fno-stack-protector"))) ... start_secondary(void *unused)
-
-however, using the optimize attribute doesn't work cumulatively
-as the attribute does not add to but rather replaces previously
-supplied optimization options - roughly all -fxxx options.
-
-The key one among them being -fno-omit-frame-pointer and thus leading to
-not present frame pointer - frame pointer which the kernel needs.
-
-The next attempt to prevent compilers from tail-call optimizing
-the last function call cpu_startup_entry(), shy of carving out
-start_secondary() into a separate compilation unit and building it with
--fno-stack-protector, is this one.
-
-The current solution is short and sweet, and reportedly, is supported by
-both compilers so let's see how far we'll get this time.
-
-Reported-by: Sergei Trofimovich <slyfox@gentoo.org>
-Signed-off-by: Borislav Petkov <bp@suse.de>
-Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
-Reviewed-by: Kees Cook <keescook@chromium.org>
-Link: https://lkml.kernel.org/r/20200314164451.346497-1-slyfox@gentoo.org
----
- arch/x86/include/asm/stackprotector.h | 7 ++++++-
- arch/x86/kernel/smpboot.c             | 8 ++++++++
- arch/x86/xen/smp_pv.c                 | 1 +
- include/linux/compiler.h              | 6 ++++++
- 4 files changed, 21 insertions(+), 1 deletion(-)
-
-diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
-index 91e29b6a86a5..9804a7957f4e 100644
---- a/arch/x86/include/asm/stackprotector.h
-+++ b/arch/x86/include/asm/stackprotector.h
-@@ -55,8 +55,13 @@
- /*
-  * Initialize the stackprotector canary value.
-  *
-- * NOTE: this must only be called from functions that never return,
-+ * NOTE: this must only be called from functions that never return
-  * and it must always be inlined.
-+ *
-+ * In addition, it should be called from a compilation unit for which
-+ * stack protector is disabled. Alternatively, the caller should not end
-+ * with a function call which gets tail-call optimized as that would
-+ * lead to checking a modified canary value.
-  */
- static __always_inline void boot_init_stack_canary(void)
- {
-diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
-index fe3ab9632f3b..4f275ac7830b 100644
---- a/arch/x86/kernel/smpboot.c
-+++ b/arch/x86/kernel/smpboot.c
-@@ -266,6 +266,14 @@ static void notrace start_secondary(void *unused)
- 
- 	wmb();
- 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
-+
-+	/*
-+	 * Prevent tail call to cpu_startup_entry() because the stack protector
-+	 * guard has been changed a couple of function calls up, in
-+	 * boot_init_stack_canary() and must not be checked before tail calling
-+	 * another function.
-+	 */
-+	prevent_tail_call_optimization();
- }
- 
- /**
-diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
-index 8fb8a50a28b4..f2adb63b2d7c 100644
---- a/arch/x86/xen/smp_pv.c
-+++ b/arch/x86/xen/smp_pv.c
-@@ -93,6 +93,7 @@ asmlinkage __visible void cpu_bringup_and_idle(void)
- 	cpu_bringup();
- 	boot_init_stack_canary();
- 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
-+	prevent_tail_call_optimization();
- }
- 
- void xen_smp_intr_free_pv(unsigned int cpu)
-diff --git a/include/linux/compiler.h b/include/linux/compiler.h
-index 034b0a644efc..732754d96039 100644
---- a/include/linux/compiler.h
-+++ b/include/linux/compiler.h
-@@ -356,4 +356,10 @@ static inline void *offset_to_ptr(const int *off)
- /* &a[0] degrades to a pointer: a different type from an array */
- #define __must_be_array(a)	BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
- 
-+/*
-+ * This is needed in functions which generate the stack canary, see
-+ * arch/x86/kernel/smpboot.c::start_secondary() for an example.
-+ */
-+#define prevent_tail_call_optimization()	asm("")
-+
- #endif /* __LINUX_COMPILER_H */
--- 
-cgit 1.2-0.3.lf.el7
-