linux-kernel - Re: [PATCH 03/13] x86/paravirt: Convert native patch assembly code strings to macros

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Wed, 25 Oct 2017 11:46:18 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <alexander.levin@...izon.com>,
        live-patching@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Mike Galbraith <efault@....de>,
        Chris Wright <chrisw@...s-sol.org>,
        Alok Kataria <akataria@...are.com>,
        Rusty Russell <rusty@...tcorp.com.au>,
        virtualization@...ts.linux-foundation.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 03/13] x86/paravirt: Convert native patch assembly code
 strings to macros

On 04/10/17 17:58, Josh Poimboeuf wrote:
> Convert the hard-coded native patch assembly code strings to macros to
> facilitate sharing common code between 32-bit and 64-bit.
> 
> These macros will also be used by a future patch which requires the GCC
> extended asm syntax of two '%' characters instead of one when specifying
> a register name.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>

Reviewed-by: Juergen Gross <jgross@...e.com>

Mind adding another patch to merge the now nearly identical
paravirt_patch_32.c and paravirt_patch_64.c either into paravirt.c
or paravirt_patch.c? This would require only very few #ifdef.


Juergen

> ---
>  arch/x86/include/asm/special_insns.h | 24 ++++++++++++++++++++++++
>  arch/x86/kernel/paravirt_patch_32.c  | 21 +++++++++++----------
>  arch/x86/kernel/paravirt_patch_64.c  | 29 +++++++++++++++--------------
>  3 files changed, 50 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
> index ac402c6fc24b..0549c5f2c1b3 100644
> --- a/arch/x86/include/asm/special_insns.h
> +++ b/arch/x86/include/asm/special_insns.h
> @@ -6,6 +6,30 @@
>  
>  #include <asm/nops.h>
>  
> +#ifdef CONFIG_X86_64
> +# define _REG_ARG1			"%rdi"
> +# define NATIVE_IDENTITY_32		"mov %edi, %eax"
> +# define NATIVE_USERGS_SYSRET64		"swapgs; sysretq"
> +#else
> +# define _REG_ARG1			"%eax"
> +#endif
> +
> +#define _REG_RET			"%" _ASM_AX
> +
> +#define NATIVE_ZERO			"xor " _REG_ARG1 ", " _REG_ARG1
> +#define NATIVE_IDENTITY			"mov " _REG_ARG1 ", " _REG_RET
> +#define NATIVE_SAVE_FL			"pushf; pop " _REG_RET
> +#define NATIVE_RESTORE_FL		"push " _REG_ARG1 "; popf"
> +#define NATIVE_IRQ_DISABLE		"cli"
> +#define NATIVE_IRQ_ENABLE		"sti"
> +#define NATIVE_READ_CR2			"mov %cr2, " _REG_RET
> +#define NATIVE_READ_CR3			"mov %cr3, " _REG_RET
> +#define NATIVE_WRITE_CR3		"mov " _REG_ARG1 ", %cr3"
> +#define NATIVE_FLUSH_TLB_SINGLE		"invlpg (" _REG_ARG1 ")"
> +#define NATIVE_SWAPGS			"swapgs"
> +#define NATIVE_IRET			"iret"
> +#define NATIVE_QUEUED_SPIN_UNLOCK	"movb $0, (" _REG_ARG1 ")"
> +
>  /*
>   * Volatile isn't enough to prevent the compiler from reordering the
>   * read/write functions for the control registers and messing everything up.
> diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c
> index 553acbbb4d32..c9c6106ae714 100644
> --- a/arch/x86/kernel/paravirt_patch_32.c
> +++ b/arch/x86/kernel/paravirt_patch_32.c
> @@ -1,17 +1,18 @@
>  #include <asm/paravirt.h>
> +#include <asm/special_insns.h>
>  
> -DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
> -DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
> -DEF_NATIVE(pv_irq_ops, restore_fl, "push %eax; popf");
> -DEF_NATIVE(pv_irq_ops, save_fl, "pushf; pop %eax");
> -DEF_NATIVE(pv_cpu_ops, iret, "iret");
> -DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
> -DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
> -DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
> +DEF_NATIVE(pv_irq_ops,	save_fl,		NATIVE_SAVE_FL);
> +DEF_NATIVE(pv_irq_ops,	restore_fl,		NATIVE_RESTORE_FL);
> +DEF_NATIVE(pv_irq_ops,	irq_disable,		NATIVE_IRQ_DISABLE);
> +DEF_NATIVE(pv_irq_ops,	irq_enable,		NATIVE_IRQ_ENABLE);
> +DEF_NATIVE(pv_cpu_ops,	iret,			NATIVE_IRET);
> +DEF_NATIVE(pv_mmu_ops,	read_cr2,		NATIVE_READ_CR2);
> +DEF_NATIVE(pv_mmu_ops,	read_cr3,		NATIVE_READ_CR3);
> +DEF_NATIVE(pv_mmu_ops,	write_cr3,		NATIVE_WRITE_CR3);
>  
>  #if defined(CONFIG_PARAVIRT_SPINLOCKS)
> -DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)");
> -DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %eax, %eax");
> +DEF_NATIVE(pv_lock_ops,	queued_spin_unlock,	NATIVE_QUEUED_SPIN_UNLOCK);
> +DEF_NATIVE(pv_lock_ops,	vcpu_is_preempted,	NATIVE_ZERO);
>  #endif
>  
>  unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
> diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
> index 0a1ba3f80cbf..0aa232edd670 100644
> --- a/arch/x86/kernel/paravirt_patch_64.c
> +++ b/arch/x86/kernel/paravirt_patch_64.c
> @@ -1,25 +1,26 @@
>  #include <asm/paravirt.h>
>  #include <asm/asm-offsets.h>
> +#include <asm/special_insns.h>
>  #include <linux/stringify.h>
>  
> -DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
> -DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
> -DEF_NATIVE(pv_irq_ops, restore_fl, "pushq %rdi; popfq");
> -DEF_NATIVE(pv_irq_ops, save_fl, "pushfq; popq %rax");
> -DEF_NATIVE(pv_mmu_ops, read_cr2, "movq %cr2, %rax");
> -DEF_NATIVE(pv_mmu_ops, read_cr3, "movq %cr3, %rax");
> -DEF_NATIVE(pv_mmu_ops, write_cr3, "movq %rdi, %cr3");
> -DEF_NATIVE(pv_mmu_ops, flush_tlb_single, "invlpg (%rdi)");
> +DEF_NATIVE(pv_irq_ops,	save_fl,		NATIVE_SAVE_FL);
> +DEF_NATIVE(pv_irq_ops,	restore_fl,		NATIVE_RESTORE_FL);
> +DEF_NATIVE(pv_irq_ops,	irq_disable,		NATIVE_IRQ_DISABLE);
> +DEF_NATIVE(pv_irq_ops,	irq_enable,		NATIVE_IRQ_ENABLE);
> +DEF_NATIVE(pv_mmu_ops,	read_cr2,		NATIVE_READ_CR2);
> +DEF_NATIVE(pv_mmu_ops,	read_cr3,		NATIVE_READ_CR3);
> +DEF_NATIVE(pv_mmu_ops,	write_cr3,		NATIVE_WRITE_CR3);
> +DEF_NATIVE(pv_mmu_ops,	flush_tlb_single,	NATIVE_FLUSH_TLB_SINGLE);
>  
> -DEF_NATIVE(pv_cpu_ops, usergs_sysret64, "swapgs; sysretq");
> -DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");
> +DEF_NATIVE(pv_cpu_ops,	usergs_sysret64,	NATIVE_USERGS_SYSRET64);
> +DEF_NATIVE(pv_cpu_ops,	swapgs,			NATIVE_SWAPGS);
>  
> -DEF_NATIVE(, mov32, "mov %edi, %eax");
> -DEF_NATIVE(, mov64, "mov %rdi, %rax");
> +DEF_NATIVE(,		mov32,			NATIVE_IDENTITY_32);
> +DEF_NATIVE(,		mov64,			NATIVE_IDENTITY);
>  
>  #if defined(CONFIG_PARAVIRT_SPINLOCKS)
> -DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%rdi)");
> -DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %rax, %rax");
> +DEF_NATIVE(pv_lock_ops,	queued_spin_unlock,	NATIVE_QUEUED_SPIN_UNLOCK);
> +DEF_NATIVE(pv_lock_ops,	vcpu_is_preempted,	NATIVE_ZERO);
>  #endif
>  
>  unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
>