linux-kernel - [PATCH v9 3/5] powerpc/vdso: Save and restore TOC pointer on PPC64

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Message-Id: <459ef960fb08d51962b9dba4dfba247f102d149d.1596541334.git.christophe.leroy@csgroup.eu>
Date:   Tue,  4 Aug 2020 11:47:50 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, nathanl@...ux.ibm.com,
        anton@...abs.org
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        arnd@...db.de, tglx@...utronix.de, vincenzo.frascino@....com,
        luto@...nel.org, linux-arch@...r.kernel.org
Subject: [PATCH v9 3/5] powerpc/vdso: Save and restore TOC pointer on PPC64

On PPC64, the TOC pointer needs to be saved and restored.

Suggested-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
v9: New.

I'm not sure this is really needed, I can't see the VDSO C code doing
anything with r2, at least on ppc64_defconfig.

So I let you decide whether you take it or not.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/vdso/gettimeofday.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index 0b6fa245d54e..fa774086173b 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -13,10 +13,16 @@
 	PPC_STLU	r1, -STACK_FRAME_OVERHEAD(r1)
   .cfi_register lr, r0
 	PPC_STL		r0, STACK_FRAME_OVERHEAD + PPC_LR_STKOFF(r1)
+#ifdef CONFIG_PPC64
+	PPC_STL		r2, STACK_FRAME_OVERHEAD + STK_GOT(r1)
+#endif
 	get_datapage	r5, r0
 	addi		r5, r5, VDSO_DATA_OFFSET
 	bl		\funct
 	PPC_LL		r0, STACK_FRAME_OVERHEAD + PPC_LR_STKOFF(r1)
+#ifdef CONFIG_PPC64
+	PPC_LL		r2, STACK_FRAME_OVERHEAD + STK_GOT(r1)
+#endif
 	cmpwi		r3, 0
 	mtlr		r0
   .cfi_restore lr
@@ -36,10 +42,16 @@
 	PPC_STLU	r1, -STACK_FRAME_OVERHEAD(r1)
   .cfi_register lr, r0
 	PPC_STL		r0, STACK_FRAME_OVERHEAD + PPC_LR_STKOFF(r1)
+#ifdef CONFIG_PPC64
+	PPC_STL		r2, STACK_FRAME_OVERHEAD + STK_GOT(r1)
+#endif
 	get_datapage	r4, r0
 	addi		r4, r4, VDSO_DATA_OFFSET
 	bl		\funct
 	PPC_LL		r0, STACK_FRAME_OVERHEAD + PPC_LR_STKOFF(r1)
+#ifdef CONFIG_PPC64
+	PPC_LL		r2, STACK_FRAME_OVERHEAD + STK_GOT(r1)
+#endif
 	crclr		so
 	mtlr		r0
   .cfi_restore lr
-- 
2.25.0