linux-kernel - [PATCH 3/4] KVM: Clean up AMD SVM debug registers load and unload

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:	Sun, 10 Dec 2006 17:11:42 -0000
From:	Avi Kivity <avi@...ranet.com>
To:	kvm-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org, akpm@...l.org, mingo@...e.hu
Subject: [PATCH 3/4] KVM: Clean up AMD SVM debug registers load and unload

By letting gcc choose the temporary register for us, we lose arch
dependency and some ugliness.  Conceivably gcc will also generate
marginally better code.

Signed-off-by: Avi Kivity <avi@...ranet.com>

Index: linux-2.6/drivers/kvm/svm.c
===================================================================
--- linux-2.6.orig/drivers/kvm/svm.c
+++ linux-2.6/drivers/kvm/svm.c
@@ -1345,53 +1345,18 @@ static void kvm_reput_irq(struct kvm_vcp
 
 static void save_db_regs(unsigned long *db_regs)
 {
-#ifdef __x86_64__
-	asm ("mov %%dr0, %%rax \n\t"
-	     "mov %%rax, %[dr0] \n\t"
-	     "mov %%dr1, %%rax \n\t"
-	     "mov %%rax, %[dr1] \n\t"
-	     "mov %%dr2, %%rax \n\t"
-	     "mov %%rax, %[dr2] \n\t"
-	     "mov %%dr3, %%rax \n\t"
-	     "mov %%rax, %[dr3] \n\t"
-	     : [dr0] "=m"(db_regs[0]),
-	       [dr1] "=m"(db_regs[1]),
-	       [dr2] "=m"(db_regs[2]),
-	       [dr3] "=m"(db_regs[3])
-	     : : "rax");
-#else
-	asm ("mov %%dr0, %%eax \n\t"
-	     "mov %%eax, %[dr0] \n\t"
-	     "mov %%dr1, %%eax \n\t"
-	     "mov %%eax, %[dr1] \n\t"
-	     "mov %%dr2, %%eax \n\t"
-	     "mov %%eax, %[dr2] \n\t"
-	     "mov %%dr3, %%eax \n\t"
-	     "mov %%eax, %[dr3] \n\t"
-	     : [dr0] "=m"(db_regs[0]),
-	       [dr1] "=m"(db_regs[1]),
-	       [dr2] "=m"(db_regs[2]),
-	       [dr3] "=m"(db_regs[3])
-	     : : "eax");
-#endif
+	asm volatile ("mov %%dr0, %0" : "=r"(db_regs[0]));
+	asm volatile ("mov %%dr1, %0" : "=r"(db_regs[1]));
+	asm volatile ("mov %%dr2, %0" : "=r"(db_regs[2]));
+	asm volatile ("mov %%dr3, %0" : "=r"(db_regs[3]));
 }
 
 static void load_db_regs(unsigned long *db_regs)
 {
-	asm volatile ("mov %[dr0], %%dr0 \n\t"
-	     "mov %[dr1], %%dr1 \n\t"
-	     "mov %[dr2], %%dr2 \n\t"
-	     "mov %[dr3], %%dr3 \n\t"
-	     :
-	     : [dr0] "r"(db_regs[0]),
-	       [dr1] "r"(db_regs[1]),
-	       [dr2] "r"(db_regs[2]),
-	       [dr3] "r"(db_regs[3])
-#ifdef __x86_64__
-	     : "rax");
-#else
-	     : "eax");
-#endif
+	asm volatile ("mov %0, %%dr0" : : "r"(db_regs[0]));
+	asm volatile ("mov %0, %%dr1" : : "r"(db_regs[1]));
+	asm volatile ("mov %0, %%dr2" : : "r"(db_regs[2]));
+	asm volatile ("mov %0, %%dr3" : : "r"(db_regs[3]));
 }
 
 static int svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/