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authorAnton Blanchard <anton@samba.org>2012-11-26 17:41:08 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-01-10 17:00:31 +1100
commit1fbe9cf2598dae3bd464d860bd89c67b1ff8682b (patch)
treec07f1fe789777669466bc3077a5f0afa70cf83b6 /arch/powerpc/kernel
parent5827d4165ac608d7c26fa68701391e80824ee5c9 (diff)
downloadlinaro-lsk-1fbe9cf2598dae3bd464d860bd89c67b1ff8682b.tar.gz
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 'arch/powerpc/kernel')
-rw-r--r--arch/powerpc/kernel/Makefile2
-rw-r--r--arch/powerpc/kernel/head_64.S15
-rw-r--r--arch/powerpc/kernel/module_64.c30
3 files changed, 44 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 2f6ef4ed5ab..b4f0e360e41 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -7,7 +7,7 @@ CFLAGS_ptrace.o += -DUTS_MACHINE='"$(UTS_MACHINE)"'
subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
ifeq ($(CONFIG_PPC64),y)
-CFLAGS_prom_init.o += -mno-minimal-toc
+CFLAGS_prom_init.o += $(NO_MINIMAL_TOC)
endif
ifeq ($(CONFIG_PPC32),y)
CFLAGS_prom_init.o += -fPIC
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 116f0868695..1697a25ebe9 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
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 9f44a775a10..6ee59a0eb26 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -386,6 +386,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
| (value & 0xffff);
break;
+ case R_PPC64_TOC16_LO:
+ /* Subtract TOC pointer */
+ value -= my_r2(sechdrs, me);
+ *((uint16_t *) location)
+ = (*((uint16_t *) location) & ~0xffff)
+ | (value & 0xffff);
+ break;
+
case R_PPC64_TOC16_DS:
/* Subtract TOC pointer */
value -= my_r2(sechdrs, me);
@@ -399,6 +407,28 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
| (value & 0xfffc);
break;
+ case R_PPC64_TOC16_LO_DS:
+ /* Subtract TOC pointer */
+ value -= my_r2(sechdrs, me);
+ if ((value & 3) != 0) {
+ printk("%s: bad TOC16_LO_DS relocation (%lu)\n",
+ me->name, value);
+ return -ENOEXEC;
+ }
+ *((uint16_t *) location)
+ = (*((uint16_t *) location) & ~0xfffc)
+ | (value & 0xfffc);
+ break;
+
+ case R_PPC64_TOC16_HA:
+ /* Subtract TOC pointer */
+ value -= my_r2(sechdrs, me);
+ value = ((value + 0x8000) >> 16);
+ *((uint16_t *) location)
+ = (*((uint16_t *) location) & ~0xffff)
+ | (value & 0xffff);
+ break;
+
case R_PPC_REL24:
/* FIXME: Handle weak symbols here --RR */
if (sym->st_shndx == SHN_UNDEF) {