[PATCH v2 27/29] x86/mm: Report which part of kernel image is freed

[Kees Cook]

The memory freeing report wasn't very useful for figuring out which
parts of the kernel image were being freed. Add the details for clearer
reporting in dmesg.

Before:

[    2.150450] Freeing unused kernel image memory: 1348K
[    2.154574] Write protecting the kernel read-only data: 20480k
[    2.157641] Freeing unused kernel image memory: 2040K
[    2.158827] Freeing unused kernel image memory: 172K

After:

[    2.329678] Freeing unused kernel image (initmem) memory: 1348K
[    2.331953] Write protecting the kernel read-only data: 20480k
[    2.335361] Freeing unused kernel image (text/rodata gap) memory: 2040K
[    2.336927] Freeing unused kernel image (rodata/data gap) memory: 172K

Signed-off-by: Kees Cook <keescook at chromium.org>
---
 arch/x86/include/asm/processor.h | 2 +-
 arch/x86/mm/init.c               | 8 ++++----
 arch/x86/mm/init_64.c            | 6 ++++--
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6e0a3b43d027..790f250d39a8 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -958,7 +958,7 @@ static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
 
 extern unsigned long arch_align_stack(unsigned long sp);
 void free_init_pages(const char *what, unsigned long begin, unsigned long end);
-extern void free_kernel_image_pages(void *begin, void *end);
+extern void free_kernel_image_pages(const char *what, void *begin, void *end);
 
 void default_idle(void);
 #ifdef	CONFIG_XEN
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index fd10d91a6115..e7bb483557c9 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -829,14 +829,13 @@ void free_init_pages(const char *what, unsigned long begin, unsigned long end)
  * used for the kernel image only.  free_init_pages() will do the
  * right thing for either kind of address.
  */
-void free_kernel_image_pages(void *begin, void *end)
+void free_kernel_image_pages(const char *what, void *begin, void *end)
 {
 	unsigned long begin_ul = (unsigned long)begin;
 	unsigned long end_ul = (unsigned long)end;
 	unsigned long len_pages = (end_ul - begin_ul) >> PAGE_SHIFT;
 
-
-	free_init_pages("unused kernel image", begin_ul, end_ul);
+	free_init_pages(what, begin_ul, end_ul);
 
 	/*
 	 * PTI maps some of the kernel into userspace.  For performance,
@@ -865,7 +864,8 @@ void __ref free_initmem(void)
 
 	mem_encrypt_free_decrypted_mem();
 
-	free_kernel_image_pages(&__init_begin, &__init_end);
+	free_kernel_image_pages("unused kernel image (initmem)",
+				&__init_begin, &__init_end);
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index e67ddca8b7a8..dcb9bc961b39 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1334,8 +1334,10 @@ void mark_rodata_ro(void)
 	set_memory_ro(start, (end-start) >> PAGE_SHIFT);
 #endif
 
-	free_kernel_image_pages((void *)text_end, (void *)rodata_start);
-	free_kernel_image_pages((void *)rodata_end, (void *)_sdata);
+	free_kernel_image_pages("unused kernel image (text/rodata gap)",
+				(void *)text_end, (void *)rodata_start);
+	free_kernel_image_pages("unused kernel image (rodata/data gap)",
+				(void *)rodata_end, (void *)_sdata);
 
 	debug_checkwx();
 }
-- 
2.17.1