Commit 42d720d1 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by Kees Cook

ARM: kexec: Make .text R/W in machine_kexec

With the introduction of Kees Cook's patch to make the kernel .text
read-only the existing method by which kexec works got broken since it
directly pokes some values in the template code, which resides in the
.text section.

The current patch changes the way those values are inserted so that poking
.text section occurs only in machine_kexec (e.g when we are about to nuke
the old kernel and are beyond the point of return). This allows to use
set_kernel_text_rw() to directly patch the values in the .text section.

I had already sent a patch which achieved this but it was significantly
more complicated, so this is a cleaner/straight-forward approach.
Signed-off-by: default avatarNikolay Borisov <Nikolay.Borisov@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
[kees: collapsed kexec_boot_atags (will.daecon)]
[kees: for bisectability, moved set_kernel_text_rw() to RODATA patch]
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
parent ab0615e2
...@@ -29,6 +29,7 @@ extern unsigned long kexec_boot_atags; ...@@ -29,6 +29,7 @@ extern unsigned long kexec_boot_atags;
static atomic_t waiting_for_crash_ipi; static atomic_t waiting_for_crash_ipi;
static unsigned long dt_mem;
/* /*
* Provide a dummy crash_notes definition while crash dump arrives to arm. * Provide a dummy crash_notes definition while crash dump arrives to arm.
* This prevents breakage of crash_notes attribute in kernel/ksysfs.c. * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
...@@ -64,7 +65,7 @@ int machine_kexec_prepare(struct kimage *image) ...@@ -64,7 +65,7 @@ int machine_kexec_prepare(struct kimage *image)
return err; return err;
if (be32_to_cpu(header) == OF_DT_HEADER) if (be32_to_cpu(header) == OF_DT_HEADER)
kexec_boot_atags = current_segment->mem; dt_mem = current_segment->mem;
} }
return 0; return 0;
} }
...@@ -166,9 +167,8 @@ void machine_kexec(struct kimage *image) ...@@ -166,9 +167,8 @@ void machine_kexec(struct kimage *image)
kexec_start_address = image->start; kexec_start_address = image->start;
kexec_indirection_page = page_list; kexec_indirection_page = page_list;
kexec_mach_type = machine_arch_type; kexec_mach_type = machine_arch_type;
if (!kexec_boot_atags) kexec_boot_atags = dt_mem ?: image->start - KEXEC_ARM_ZIMAGE_OFFSET
kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET; + KEXEC_ARM_ATAGS_OFFSET;
/* copy our kernel relocation code to the control code page */ /* copy our kernel relocation code to the control code page */
reboot_entry = fncpy(reboot_code_buffer, reboot_entry = fncpy(reboot_code_buffer,
......
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