linux-kernel - [PATCH v2 03/10] um: vdso: Implement __vdso

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]

Message-Id: <20250810055136.897712-4-tiwei.bie@linux.dev>
Date: Sun, 10 Aug 2025 13:51:29 +0800
From: Tiwei Bie <tiwei.bie@...ux.dev>
To: richard@....at,
	anton.ivanov@...bridgegreys.com,
	johannes@...solutions.net
Cc: linux-um@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	benjamin@...solutions.net,
	arnd@...db.de,
	tiwei.btw@...group.com,
	tiwei.bie@...ux.dev
Subject: [PATCH v2 03/10] um: vdso: Implement __vdso_getcpu() via syscall

From: Tiwei Bie <tiwei.btw@...group.com>

We are going to support SMP in UML, so we can not hard code
the CPU and NUMA node in __vdso_getcpu() anymore.

Signed-off-by: Tiwei Bie <tiwei.btw@...group.com>
---
 arch/x86/um/vdso/um_vdso.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
index cbae2584124f..ee40ac446c1c 100644
--- a/arch/x86/um/vdso/um_vdso.c
+++ b/arch/x86/um/vdso/um_vdso.c
@@ -17,7 +17,7 @@
 int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts);
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
 __kernel_old_time_t __vdso_time(__kernel_old_time_t *t);
-long __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
+long __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *tcache);
 
 int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
 {
@@ -60,18 +60,16 @@ __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 __kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
 
 long
-__vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
+__vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *tcache)
 {
-	/*
-	 * UML does not support SMP, we can cheat here. :)
-	 */
+	long ret;
 
-	if (cpu)
-		*cpu = 0;
-	if (node)
-		*node = 0;
+	asm volatile("syscall"
+		: "=a" (ret)
+		: "0" (__NR_getcpu), "D" (cpu), "S" (node), "d" (tcache)
+		: "rcx", "r11", "memory");
 
-	return 0;
+	return ret;
 }
 
 long getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *tcache)
-- 
2.34.1