From: tip-bot for Josh Poimboeuf <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: jpoimboe@redhat.com, peterz@infradead.org, brgerst@gmail.com,
tglx@linutronix.de, hpa@zytor.com, luto@kernel.org,
torvalds@linux-foundation.org, mingo@kernel.org,
linux-kernel@vger.kernel.org, dvlasenk@redhat.com, bp@alien8.de,
nilayvaish@gmail.com
Subject: [tip:x86/asm] x86/boot/32: Fix the end of the stack for idle tasks
Date: Thu, 20 Oct 2016 04:10:03 -0700 [thread overview]
Message-ID: <tip-6616a147a79c6fc280572f5a993e9e5ebd200d24@git.kernel.org> (raw)
In-Reply-To: <2588f34b6fbac4ae6f6f9ead2a78d7f8d58a6341.1474480779.git.jpoimboe@redhat.com>
Commit-ID: 6616a147a79c6fc280572f5a993e9e5ebd200d24
Gitweb: http://git.kernel.org/tip/6616a147a79c6fc280572f5a993e9e5ebd200d24
Author: Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Wed, 21 Sep 2016 16:04:02 -0500
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 20 Oct 2016 09:15:23 +0200
x86/boot/32: Fix the end of the stack for idle tasks
The frame at the end of each idle task stack is inconsistent with real
task stacks, which have a stack frame header and a real return address
before the pt_regs area. This inconsistency can be confusing for stack
unwinders. It also hides useful information about what asm code was
involved in calling into C.
Fix that by changing the initial code jumps to calls. Also add infinite
loops after the calls to make it clear that the calls don't return, and
to hang if they do.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2588f34b6fbac4ae6f6f9ead2a78d7f8d58a6341.1474480779.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/head_32.S | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 65e6225..9a6f8e8 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -289,7 +289,8 @@ num_subarch_entries = (. - subarch_entries) / 4
ENTRY(start_cpu0)
movl initial_stack, %ecx
movl %ecx, %esp
- jmp *(initial_code)
+ call *(initial_code)
+1: jmp 1b
ENDPROC(start_cpu0)
#endif
@@ -470,8 +471,9 @@ ENTRY(startup_32_smp)
xorl %eax,%eax # Clear LDT
lldt %ax
- pushl $0 # fake return address for unwinder
- jmp *(initial_code)
+ call *(initial_code)
+1: jmp 1b
+ENDPROC(startup_32_smp)
#include "verify_cpu.S"
next prev parent reply other threads:[~2016-10-20 11:10 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 21:03 [PATCH v2 0/9] x86/entry/head: standardize the end of the stack Josh Poimboeuf
2016-09-21 21:03 ` [PATCH v2 1/9] x86/entry/head/32: use local labels Josh Poimboeuf
2016-10-20 11:08 ` [tip:x86/asm] x86/entry/32, x86/boot/32: Use " tip-bot for Josh Poimboeuf
2016-09-21 21:04 ` [PATCH v2 2/9] x86/entry/32: rename 'error_code' to 'common_exception' Josh Poimboeuf
2016-10-20 11:08 ` [tip:x86/asm] x86/entry/32: Rename " tip-bot for Josh Poimboeuf
2016-09-21 21:04 ` [PATCH v2 3/9] x86/entry/32: fix the end of the stack for newly forked tasks Josh Poimboeuf
2016-10-20 11:09 ` [tip:x86/asm] x86/entry/32: Fix " tip-bot for Josh Poimboeuf
2016-09-21 21:04 ` [PATCH v2 4/9] x86/head/32: fix the end of the stack for idle tasks Josh Poimboeuf
2016-10-20 11:10 ` tip-bot for Josh Poimboeuf [this message]
2016-09-21 21:04 ` [PATCH v2 5/9] x86/smp: fix initial idle stack location on 32-bit Josh Poimboeuf
2016-10-20 11:10 ` [tip:x86/asm] x86/boot/smp/32: Fix initial idle stack location on 32-bit kernels tip-bot for Josh Poimboeuf
2016-09-21 21:04 ` [PATCH v2 6/9] x86/asm/head: use a common function for starting CPUs Josh Poimboeuf
2016-10-20 11:11 ` [tip:x86/asm] x86/boot/64: Use " tip-bot for Josh Poimboeuf
2016-09-21 21:04 ` [PATCH v2 7/9] x86/head: put real return address on idle task stack Josh Poimboeuf
2016-10-20 11:11 ` [tip:x86/asm] x86/boot/64: Put a real return address on the " tip-bot for Josh Poimboeuf
2016-09-21 21:04 ` [PATCH v2 8/9] x86/head: fix the end of the stack for idle tasks Josh Poimboeuf
2016-10-20 11:12 ` [tip:x86/asm] x86/boot: Fix " tip-bot for Josh Poimboeuf
2016-09-21 21:04 ` [PATCH v2 9/9] x86: move _stext marker to before head code Josh Poimboeuf
2016-10-20 11:12 ` [tip:x86/asm] x86/boot: Move the _stext marker to before the boot code tip-bot for Josh Poimboeuf
2016-10-18 17:17 ` [PATCH v2 0/9] x86/entry/head: standardize the end of the stack Josh Poimboeuf
2016-10-19 13:20 ` Ingo Molnar
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