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From: "H.J. Lu" <hjl.tools@gmail.com>
To: gnu-gabi@sourceware.org,
		IA32 System V Application Binary Interface
	<ia32-abi@googlegroups.com>,
		"x86-64-abi@googlegroups.com" <x86-64-abi@googlegroups.com>
Subject: RFC: Update x86 psABI to support shadow stac
Date: Sun, 01 Jan 2017 00:00:00 -0000	[thread overview]
Message-ID: <CAMe9rOq9-LXXzNQy8ov67rJM6rfQP=7+sWnK_RdHbe2OTiULtw@mail.gmail.com> (raw)

Any comments?

-- 
H.J.
---
To support shadow stack (SHSTK) in Intel Control-flow Enforcement
Technology (CET) instructions:

https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforc
ement-technology-preview.pdf

following changes to x86 psABI are required.

To program properties, add

#define GNU_PROPERTY_X86_FEATURE_1_SHSTK (1U << 1)

to the GNU_PROPERTY_X86_FEATURE_1_AND property to indicate that all
executable sections are compatible with SHSTK where return address
popped from shadow stack always matches return address popped from
normal stack.

GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on output only if it is set on
all relocatable inputs, which means that the C library must be compiled
with SHSTK-enabled compiler.

Load-time processing

On a SHSTK capable processor, the following steps should be taken:

1. When loading an executable, if GNU_PROPERTY_X86_FEATURE_1_SHSTK is
set on the executable as well as all shared objects loaded via the
DT_NEEDED tag, enable SHSTK.
2. After SHSTK is enabled, it is an error to load a shared object
without GNU_PROPERTY_X86_FEATURE_1_SHSTK.
gnu-6:pts/8[8]> cat  shstk.txt                /export/gnu/import/git/properties
Update x86 psABI to support shadow stack

To support shadow stack (SHSTK) in Intel Control-flow Enforcement
Technology (CET) instructions:

https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf

following changes to x86 psABI are required.

To program properties, add

#define GNU_PROPERTY_X86_FEATURE_1_SHSTK (1U << 1)

to the GNU_PROPERTY_X86_FEATURE_1_AND property to indicate that all
executable sections are compatible with SHSTK where return address
popped from shadow stack always matches return address popped from
normal stack.

GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on output only if it is set on
all relocatable inputs, which means that the C library must be compiled
with SHSTK-enabled compiler.

Load-time processing

On a SHSTK capable processor, the following steps should be taken:

1. When loading an executable, if GNU_PROPERTY_X86_FEATURE_1_SHSTK is
set on the executable as well as all shared objects loaded via the
DT_NEEDED tag, enable SHSTK.
2. After SHSTK is enabled, it is an error to load a shared object
without GNU_PROPERTY_X86_FEATURE_1_SHSTK.

             reply	other threads:[~2017-06-21 15:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-01  0:00 H.J. Lu [this message]
2017-01-01  0:00 ` Florian Weimer
2017-01-01  0:00   ` H.J. Lu
2017-01-01  0:00     ` Florian Weimer
2017-01-01  0:00       ` H.J. Lu
2017-01-01  0:00         ` Florian Weimer
2017-01-01  0:00           ` H.J. Lu
2017-01-01  0:00             ` Florian Weimer
2017-01-01  0:00               ` H.J. Lu
2017-01-01  0:00                 ` Florian Weimer
2017-01-01  0:00                   ` H.J. Lu
2017-01-01  0:00         ` Shanbhogue, Vedvyas

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