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From: Russell Currey <ruscur@russell.cc>
To: linuxppc-dev@lists.ozlabs.org
Cc: Russell Currey <ruscur@russell.cc>
Subject: [PATCH] powerpc/64: Fix booting large kernels with STRICT_KERNEL_RWX
Date: Wed, 27 Mar 2019 14:35:54 +1100	[thread overview]
Message-ID: <20190327033554.4926-1-ruscur@russell.cc> (raw)

With STRICT_KERNEL_RWX enabled anything marked __init is placed at a 16M
boundary.  This is necessary so that it can be repurposed later with
different permissions.  However, in kernels with text larger than 16M,
this pushes early_setup past 32M, incapable of being reached by the
branch instruction.

Fix this by setting the CTR and branching there instead.

Fixes: 1e0fc9d1eb2b ("powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs")
Signed-off-by: Russell Currey <ruscur@russell.cc>
---
 arch/powerpc/kernel/head_64.S | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 3fad8d499767..c2b53febadd9 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -968,7 +968,9 @@ start_here_multiplatform:
 
 	/* Restore parameters passed from prom_init/kexec */
 	mr	r3,r31
-	bl	early_setup		/* also sets r13 and SPRG_PACA */
+	LOAD_REG_ADDR(r12, early_setup)
+	mtctr	r12
+	bctrl		/* also sets r13 and SPRG_PACA */
 
 	LOAD_REG_ADDR(r3, start_here_common)
 	ld	r4,PACAKMSR(r13)
-- 
2.21.0


             reply	other threads:[~2019-03-27  3:38 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-27  3:35 Russell Currey [this message]
2019-04-21 14:18 ` powerpc/64: Fix booting large kernels with STRICT_KERNEL_RWX Michael Ellerman

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