Subject: [PATCH v2 28/29] x86/mm: Report actual image regions in /proc/iomem

From: Kees Cook <[email-masked]>
Date: Thu, 10 Oct 2019 17:06:08 -0700

The resource reservations in /proc/iomem made for the kernel image did
not reflect the gaps between text, rodata, and data. Add the "rodata"
resource and update the start/end calculations to match the respective
calls to free_kernel_image_pages().

Before (booted with "nokaslr" for easier comparison):

00100000-bffd9fff : System RAM
  01000000-01e011d0 : Kernel code
  01e011d1-025619bf : Kernel data
  02a95000-035fffff : Kernel bss

After:

00100000-bffd9fff : System RAM
  01000000-01e011d0 : Kernel code
  02000000-023d4fff : Kernel rodata
  02400000-025619ff : Kernel data
  02a95000-035fffff : Kernel bss

Signed-off-by: Kees Cook <[email-masked]>
---
 arch/x86/kernel/setup.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 77ea96b794bd..591e885a852e 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -143,6 +143,13 @@ struct boot_params boot_params;
 /*
  * Machine setup..
  */
+static struct resource rodata_resource = {
+	.name	= "Kernel rodata",
+	.start	= 0,
+	.end	= 0,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM
+};
+
 static struct resource data_resource = {
 	.name	= "Kernel data",
 	.start	= 0,
@@ -951,7 +958,9 @@ void __init setup_arch(char **cmdline_p)
 
 	code_resource.start = __pa_symbol(_text);
 	code_resource.end = __pa_symbol(_etext)-1;
-	data_resource.start = __pa_symbol(_etext);
+	rodata_resource.start = __pa_symbol(__start_rodata);
+	rodata_resource.end = __pa_symbol(__end_rodata)-1;
+	data_resource.start = __pa_symbol(_sdata);
 	data_resource.end = __pa_symbol(_edata)-1;
 	bss_resource.start = __pa_symbol(__bss_start);
 	bss_resource.end = __pa_symbol(__bss_stop)-1;
@@ -1040,6 +1049,7 @@ void __init setup_arch(char **cmdline_p)
 
 	/* after parse_early_param, so could debug it */
 	insert_resource(&iomem_resource, &code_resource);
+	insert_resource(&iomem_resource, &rodata_resource);
 	insert_resource(&iomem_resource, &data_resource);
 	insert_resource(&iomem_resource, &bss_resource);
 
-- 
2.17.1

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