[RFC PATCH v2] powerpc: fix kexec failure on book3s/32

[Christophe Leroy]

Fixes: 63b2bc619565 ("powerpc/mm/32s: Use BATs for STRICT_KERNEL_RWX")
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
 arch/powerpc/kernel/machine_kexec_32.c | 8 ++++++++
 arch/powerpc/mm/book3s32/mmu.c         | 7 +++++--
 arch/powerpc/mm/mmu_decl.h             | 2 ++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/machine_kexec_32.c b/arch/powerpc/kernel/machine_kexec_32.c
index affe5dcce7f4..83e61a8f8468 100644
--- a/arch/powerpc/kernel/machine_kexec_32.c
+++ b/arch/powerpc/kernel/machine_kexec_32.c
@@ -15,6 +15,7 @@
 #include <asm/cacheflush.h>
 #include <asm/hw_irq.h>
 #include <asm/io.h>
+#include <mm/mmu_decl.h>
 
 typedef void (*relocate_new_kernel_t)(
 				unsigned long indirection_page,
@@ -35,6 +36,8 @@ void default_machine_kexec(struct kimage *image)
 	unsigned long page_list;
 	unsigned long reboot_code_buffer, reboot_code_buffer_phys;
 	relocate_new_kernel_t rnk;
+	unsigned long bat_size = 128 << 10;
+	unsigned long bat_mask = ~(bat_size - 1);
 
 	/* Interrupts aren't acceptable while we reboot */
 	local_irq_disable();
@@ -54,6 +57,11 @@ void default_machine_kexec(struct kimage *image)
 	memcpy((void *)reboot_code_buffer, relocate_new_kernel,
 						relocate_new_kernel_size);
 
+	printk(KERN_INFO "Reboot code buffer at %lx\n", reboot_code_buffer);
+	mtsrin(mfsrin(reboot_code_buffer) & ~SR_NX, reboot_code_buffer);
+	setibat(7, reboot_code_buffer & bat_mask, reboot_code_buffer_phys & bat_mask,
+		bat_size, PAGE_KERNEL_TEXT);
+
 	flush_icache_range(reboot_code_buffer,
 				reboot_code_buffer + KEXEC_CONTROL_PAGE_SIZE);
 	printk(KERN_INFO "Bye!\n");
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index fc073cb2c517..7124700edb0f 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -124,8 +124,8 @@ static unsigned int block_size(unsigned long base, unsigned long top)
  * of 2 between 128k and 256M.
  * Only for 603+ ...
  */
-static void setibat(int index, unsigned long virt, phys_addr_t phys,
-		    unsigned int size, pgprot_t prot)
+void setibat(int index, unsigned long virt, phys_addr_t phys,
+	     unsigned int size, pgprot_t prot)
 {
 	unsigned int bl = (size >> 17) - 1;
 	int wimgxpp;
@@ -197,6 +197,9 @@ void mmu_mark_initmem_nx(void)
 	if (cpu_has_feature(CPU_FTR_601))
 		return;
 
+	if (IS_ENABLED(CONFIG_KEXEC))
+		nb--;
+
 	for (i = 0; i < nb - 1 && base < top && top - base > (128 << 10);) {
 		size = block_size(base, top);
 		setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT);
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 7bac0aa2026a..478584d50cf2 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -103,6 +103,8 @@ void print_system_hash_info(void);
 extern void mapin_ram(void);
 extern void setbat(int index, unsigned long virt, phys_addr_t phys,
 		   unsigned int size, pgprot_t prot);
+void setibat(int index, unsigned long virt, phys_addr_t phys,
+	     unsigned int size, pgprot_t prot);
 
 extern int __map_without_bats;
 extern unsigned int rtas_data, rtas_size;
-- 
2.13.3