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

Kees Cook
2019-10-11T00:06:08Z

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 <keescook@chromium.org>
---
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