diff options
| author |   Anton Blanchard <anton@samba.org> | 2012-11-26 17:41:08 +0000 |
|---|---|---|
| committer |   Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-01-10 17:00:31 +1100 |
| commit | 1fbe9cf2598dae3bd464d860bd89c67b1ff8682b (patch) | |
| tree | c07f1fe789777669466bc3077a5f0afa70cf83b6 /arch/powerpc/kernel/head_64.S | |
| parent | powerpc: Remove RELOC() macro (diff) | |
| download | linux-dev-1fbe9cf2598dae3bd464d860bd89c67b1ff8682b.tar.xz linux-dev-1fbe9cf2598dae3bd464d860bd89c67b1ff8682b.zip | |
powerpc: Build kernel with -mcmodel=medium
Finally remove the two level TOC and build with -mcmodel=medium.
Unfortunately we can't build modules with -mcmodel=medium due to
the tricks the kernel module loader plays with percpu data:
# -mcmodel=medium breaks modules because it uses 32bit offsets from
# the TOC pointer to create pointers where possible. Pointers into the
# percpu data area are created by this method.
#
# The kernel module loader relocates the percpu data section from the
# original location (starting with 0xd...) to somewhere in the base
# kernel percpu data space (starting with 0xc...). We need a full
# 64bit relocation for this to work, hence -mcmodel=large.
On older kernels we fall back to the two level TOC (-mminimal-toc)
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to '')
| -rw-r--r-- | arch/powerpc/kernel/head_64.S | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 116f0868695b..1697a25ebe91 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -169,6 +169,7 @@ _GLOBAL(generic_secondary_thread_init) /* get a valid TOC pointer, wherever we're mapped at */ bl .relative_toc + tovirt(r2,r2) #ifdef CONFIG_PPC_BOOK3E /* Book3E initialization */ @@ -195,6 +196,7 @@ _GLOBAL(generic_secondary_smp_init) /* get a valid TOC pointer, wherever we're mapped at */ bl .relative_toc + tovirt(r2,r2) #ifdef CONFIG_PPC_BOOK3E /* Book3E initialization */ @@ -531,6 +533,7 @@ _GLOBAL(pmac_secondary_start) /* get TOC pointer (real address) */ bl .relative_toc + tovirt(r2,r2) /* Copy some CPU settings from CPU 0 */ bl .__restore_cpu_ppc970 @@ -665,6 +668,13 @@ _GLOBAL(enable_64b_mode) * This puts the TOC pointer into r2, offset by 0x8000 (as expected * by the toolchain). It computes the correct value for wherever we * are running at the moment, using position-independent code. + * + * Note: The compiler constructs pointers using offsets from the + * TOC in -mcmodel=medium mode. After we relocate to 0 but before + * the MMU is on we need our TOC to be a virtual address otherwise + * these pointers will be real addresses which may get stored and + * accessed later with the MMU on. We use tovirt() at the call + * sites to handle this. */ _GLOBAL(relative_toc) mflr r0 @@ -681,8 +691,9 @@ p_toc: .llong __toc_start + 0x8000 - 0b * This is where the main kernel code starts. */ _INIT_STATIC(start_here_multiplatform) - /* set up the TOC (real address) */ - bl .relative_toc + /* set up the TOC */ + bl .relative_toc + tovirt(r2,r2) /* Clear out the BSS. It may have been done in prom_init, * already but that's irrelevant since prom_init will soon |