[RFC PATCH 08/10] powerpc/fsl_booke/kaslr: clear the original kernel if randomized

[Jason Yan]

The original kernel still exists in the memory, clear it now.

Signed-off-by: Jason Yan <yanaijie at huawei.com>
Cc: Diana Craciun <diana.craciun at nxp.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy at c-s.fr>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Paul Mackerras <paulus at samba.org>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: Kees Cook <keescook at chromium.org>
---
 arch/powerpc/kernel/kaslr_booke.c  | 11 +++++++++++
 arch/powerpc/mm/mmu_decl.h         |  2 ++
 arch/powerpc/mm/nohash/fsl_booke.c |  1 +
 3 files changed, 14 insertions(+)

diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c
index 90357f4bd313..00339c05879f 100644
--- a/arch/powerpc/kernel/kaslr_booke.c
+++ b/arch/powerpc/kernel/kaslr_booke.c
@@ -412,3 +412,14 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
 
 	reloc_kernel_entry(dt_ptr, kimage_vaddr);
 }
+
+void __init kaslr_second_init(void)
+{
+	/* If randomized, clear the original kernel */
+	if (kimage_vaddr != KERNELBASE) {
+		unsigned long kernel_sz;
+
+		kernel_sz = (unsigned long)_end - kimage_vaddr;
+		memset((void *)KERNELBASE, 0, kernel_sz);
+	}
+}
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 754ae1e69f92..9912ee598f9b 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -150,8 +150,10 @@ extern void loadcam_multi(int first_idx, int num, int tmp_idx);
 
 #ifdef CONFIG_RANDOMIZE_BASE
 extern void kaslr_early_init(void *dt_ptr, phys_addr_t size);
+extern void kaslr_second_init(void);
 #else
 static inline void kaslr_early_init(void *dt_ptr, phys_addr_t size) {}
+static inline void kaslr_second_init(void) {}
 #endif
 
 struct tlbcam {
diff --git a/arch/powerpc/mm/nohash/fsl_booke.c b/arch/powerpc/mm/nohash/fsl_booke.c
index 8d25a8dc965f..fa5a87f5c08e 100644
--- a/arch/powerpc/mm/nohash/fsl_booke.c
+++ b/arch/powerpc/mm/nohash/fsl_booke.c
@@ -269,6 +269,7 @@ notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start)
 	kernstart_addr = start;
 	if (is_second_reloc) {
 		virt_phys_offset = PAGE_OFFSET - memstart_addr;
+		kaslr_second_init();
 		return;
 	}
 
-- 
2.17.2