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powerpc/64: Fix booting large kernels with STRICT_KERNEL_RWX

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[ Upstream commit 56c46bba9bbfe229b4472a5be313c44c5b714a39 ]

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>
[mpe: Fix it to work on BE by using DOTSYM()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Russell Currey 2019-03-27 14:35:54 +11:00 committed by Greg Kroah-Hartman
parent 667890535f
commit a66c556e48
1 changed files with 3 additions and 1 deletions
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4
arch/powerpc/kernel/head_64.S
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@ -961,7 +961,9 @@ 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, DOTSYM(early_setup))
mtctr r12
bctrl /* also sets r13 and SPRG_PACA */
LOAD_REG_ADDR(r3, start_here_common)
ld r4,PACAKMSR(r13)