From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELv4SNHTFRC46lhdJ7jxPJE5jIBSlmwKTT0pxoyZc/0o5x9VuiMwIqK4d2cx3rOXGyCsgGfA ARC-Seal: i=1; a=rsa-sha256; t=1520955634; cv=none; d=google.com; s=arc-20160816; b=0y3pwgJYkOshA2+SEnQIuc0pR1e3K2H95fN4Cl95YelVI4olzJylbjOh+RphXTGlP4 mkDJF7nsL+YKcEbMcaEDzv4eQyezLcV8tc7WK9tN8h86y5KST2J5gg2NSSeugNYy0JkH tDAgtmiEFtT/m/QaJEzaBKxMh632jGLKyNarS/3sRQSv8BXF1LOldjnOfRa3LvOyNXoZ RGVUem3Bzdk/VmdUddx+pjnGPm0Q6Yjg0R5a+s9paET6p5eRXm/EC/s7yd+ghBYsOjVI 0k52moNkgTcKIzim3VB7HLjLp3IeMjN+1JebiYp8W0mKX9RALdPsazJUo7dR/73cCrr1 knJg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=l5Hvs/5oqH366Dqn/JBOKdZNaZkAyHXwYdBVmo7+Abo=; b=bQP+JyfWHpHf3bXdjh/PcJAttxr0kN125+fktCgU0uC9QYbU4felMyH9pa3XwUiaeb xjt2Jd66cL3FbaRxs9cNOnQNxIaU8fouh9lClAfKRein4/FIKMxxXqFjyiZFgRe5dGNB n0iDsHlBdtGNkIJG3H5rLeFNjS5alt78I5EHTYLZcgJkFoYcN5Z60YyYJX/uRB9DgnQt AhETDoVU+BxSihxf4PrRgKFgxiKXQ+HsIHl0ZWzuWnQa2i60Ofy/bskEvwLrVfAx333u Wfe6049jZLII2oOw9JahMtBhwScX/XmBLjKTWPl7vV4+fp/OvuOD+MzkVubJbqpM763b 8v9A== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dominik Brodowski , Andy Lutomirski , Arjan van de Ven , Borislav Petkov , Dan Williams , Dave Hansen , David Woodhouse , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.14 117/140] x86/entry: Reduce the code footprint of the idtentry macro Date: Tue, 13 Mar 2018 16:25:20 +0100 Message-Id: <20180313152506.041009029@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180313152458.201155692@linuxfoundation.org> References: <20180313152458.201155692@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1594836994350650853?= X-GMAIL-MSGID: =?utf-8?q?1594837575737521230?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dominik Brodowski commit 9e809d15d6b692fa061d74be7aaab1c79f6784b8 upstream. Play a little trick in the generic PUSH_AND_CLEAR_REGS macro to insert the GP registers "above" the original return address. This allows us to (re-)insert the macro in error_entry() and paranoid_entry() and to remove it from the idtentry macro. This reduces the static footprint significantly: text data bss dec hex filename 24307 0 0 24307 5ef3 entry_64.o-orig 20987 0 0 20987 51fb entry_64.o Co-developed-by: Linus Torvalds Signed-off-by: Dominik Brodowski Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: Dave Hansen Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180214175924.23065-2-linux@dominikbrodowski.net [ Small tweaks to comments. ] Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/calling.h | 11 ++++++++++- arch/x86/entry/entry_64.S | 18 ++++++++---------- 2 files changed, 18 insertions(+), 11 deletions(-) --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -97,7 +97,7 @@ For 32-bit we have the following convent #define SIZEOF_PTREGS 21*8 -.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax +.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0 /* * Push registers and sanitize registers of values that a * speculation attack might otherwise want to exploit. The @@ -105,8 +105,14 @@ For 32-bit we have the following convent * could be put to use in a speculative execution gadget. * Interleave XOR with PUSH for better uop scheduling: */ + .if \save_ret + pushq %rsi /* pt_regs->si */ + movq 8(%rsp), %rsi /* temporarily store the return address in %rsi */ + movq %rdi, 8(%rsp) /* pt_regs->di (overwriting original return address) */ + .else pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ + .endif pushq \rdx /* pt_regs->dx */ pushq %rcx /* pt_regs->cx */ pushq \rax /* pt_regs->ax */ @@ -131,6 +137,9 @@ For 32-bit we have the following convent pushq %r15 /* pt_regs->r15 */ xorq %r15, %r15 /* nospec r15*/ UNWIND_HINT_REGS + .if \save_ret + pushq %rsi /* return address on top of stack */ + .endif .endm .macro POP_REGS pop_rdi=1 skip_r11rcx=0 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -867,12 +867,8 @@ ENTRY(\sym) pushq $-1 /* ORIG_RAX: no syscall to restart */ .endif - /* Save all registers in pt_regs */ - PUSH_AND_CLEAR_REGS - ENCODE_FRAME_POINTER - .if \paranoid < 2 - testb $3, CS(%rsp) /* If coming from userspace, switch stacks */ + testb $3, CS-ORIG_RAX(%rsp) /* If coming from userspace, switch stacks */ jnz .Lfrom_usermode_switch_stack_\@ .endif @@ -1117,13 +1113,15 @@ idtentry machine_check do_mce has_err #endif /* - * Switch gs if needed. + * Save all registers in pt_regs, and switch gs if needed. * Use slow, but surefire "are we in kernel?" check. * Return: ebx=0: need swapgs on exit, ebx=1: otherwise */ ENTRY(paranoid_entry) UNWIND_HINT_FUNC cld + PUSH_AND_CLEAR_REGS save_ret=1 + ENCODE_FRAME_POINTER 8 movl $1, %ebx movl $MSR_GS_BASE, %ecx rdmsr @@ -1168,12 +1166,14 @@ ENTRY(paranoid_exit) END(paranoid_exit) /* - * Switch gs if needed. + * Save all registers in pt_regs, and switch GS if needed. * Return: EBX=0: came from user mode; EBX=1: otherwise */ ENTRY(error_entry) - UNWIND_HINT_REGS offset=8 + UNWIND_HINT_FUNC cld + PUSH_AND_CLEAR_REGS save_ret=1 + ENCODE_FRAME_POINTER 8 testb $3, CS+8(%rsp) jz .Lerror_kernelspace @@ -1564,8 +1564,6 @@ end_repeat_nmi: * frame to point back to repeat_nmi. */ pushq $-1 /* ORIG_RAX: no syscall to restart */ - PUSH_AND_CLEAR_REGS - ENCODE_FRAME_POINTER /* * Use paranoid_entry to handle SWAPGS, but no need to use paranoid_exit