linux-kernel - [PATCH 2/3] x86/vdso: Provide getcpu for x86-32.

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Date:   Fri, 25 Nov 2022 10:42:15 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Roland Mainz <roland.mainz@...bsig.org>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 2/3] x86/vdso: Provide getcpu for x86-32.

Wire up __vdso_getcpu() for x86-32. The version for 64bit can be reused.
The defines must no be faked (like it is done for vclock_gettime.c)
because we need the 64bit defines for the 32bit VDSO because the segment
number of the host kernel is required.

Reuse the vgetcpu.c for vdso32. Remove the time* header files which lead
to compile errors on 32bit. Add segment.h which provides
vdso_read_cpunode() and its requirements.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 arch/x86/entry/vdso/Makefile            | 3 ++-
 arch/x86/entry/vdso/vdso32/vdso32.lds.S | 1 +
 arch/x86/entry/vdso/vdso32/vgetcpu.c    | 2 ++
 arch/x86/entry/vdso/vgetcpu.c           | 3 +--
 4 files changed, 6 insertions(+), 3 deletions(-)
 create mode 100644 arch/x86/entry/vdso/vdso32/vgetcpu.c

diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 3e88b9df8c8f1..fcbcfc2b4e1a7 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -29,7 +29,7 @@ VDSO32-$(CONFIG_IA32_EMULATION)	:= y
 # files to link into the vdso
 vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
 vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
-vobjs32-y += vdso32/vclock_gettime.o
+vobjs32-y += vdso32/vclock_gettime.o vdso32/vgetcpu.o
 vobjs-$(CONFIG_X86_SGX)	+= vsgx.o
 
 # files to link into kernel
@@ -103,6 +103,7 @@ $(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO
 CFLAGS_REMOVE_vclock_gettime.o = -pg
 CFLAGS_REMOVE_vdso32/vclock_gettime.o = -pg
 CFLAGS_REMOVE_vgetcpu.o = -pg
+CFLAGS_REMOVE_vdso32/vgetcpu.o = -pg
 CFLAGS_REMOVE_vsgx.o = -pg
 
 #
diff --git a/arch/x86/entry/vdso/vdso32/vdso32.lds.S b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
index c7720995ab1af..8a3be07006bb6 100644
--- a/arch/x86/entry/vdso/vdso32/vdso32.lds.S
+++ b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
@@ -28,6 +28,7 @@ VERSION
 		__vdso_time;
 		__vdso_clock_getres;
 		__vdso_clock_gettime64;
+		__vdso_getcpu;
 	};
 
 	LINUX_2.5 {
diff --git a/arch/x86/entry/vdso/vdso32/vgetcpu.c b/arch/x86/entry/vdso/vdso32/vgetcpu.c
new file mode 100644
index 0000000000000..b777f84ffae9b
--- /dev/null
+++ b/arch/x86/entry/vdso/vdso32/vgetcpu.c
@@ -0,0 +1,2 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "../vgetcpu.c"
diff --git a/arch/x86/entry/vdso/vgetcpu.c b/arch/x86/entry/vdso/vgetcpu.c
index b88a82bbc3593..0a9007c240568 100644
--- a/arch/x86/entry/vdso/vgetcpu.c
+++ b/arch/x86/entry/vdso/vgetcpu.c
@@ -7,8 +7,7 @@
 
 #include <linux/kernel.h>
 #include <linux/getcpu.h>
-#include <linux/time.h>
-#include <asm/vgtod.h>
+#include <asm/segment.h>
 
 notrace long
 __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
-- 
2.38.1