This patch fix a problem introduced by commit e5d6a55 which make ARM
kexec fails.
Due to that commit, kernel is loaded at a dynamically offset: it computes
extra_size using size of dtb, and load zImage at base + extra_size. When
dtb size small (for example, 0x3000 bytes), kernel will be loaded at
address like 0x60003000. For ARM zImage such address is incorrect.
In kernel code arch/arm/boot/compressed/head.S, zImage builds a
temporary page table at (pc & 0xf8000000) + TEXT_OFFSET - 0x4000. The
related instructions sequence is:
mov r4, pc
and r4, r4, #0xf8000000
add r4, r4, #TEXT_OFFSET @ (TEXT_OFFSET == 0x8000 on most platforms)
call cache_on
...
call __armv7_mmu_cache_on
...
call __setup_mmu
sub r3, r4, #16384 @ Page directory size
r3 becomes page table pointer.
When kernel is loaded at 0x60003000, page table is still built at
0x60004000, which destroys kernel.
This patch make extra_size a fix value (0x8000) to avoid the failure.
For the problem commit e5d6a55 tries solve, this patch uses
locate_holes() to find a place can hold initrd and dtb.
Signed-off-by: Wang Nan <wangnan0 at huawei.com>
Cc: Daniel Mack <zonque at gmail.com>
Cc: Sven Neumann <s.neumann at raumfeld.com>
Cc: Geng Hui <hui.geng at huawei.com>
---
kexec/arch/arm/kexec-zImage-arm.c | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)
diff --git a/kexec/arch/arm/kexec-zImage-arm.c b/kexec/arch/arm/kexec-zImage-arm.c
index 4b5d3f4..539192b 100644
--- a/kexec/arch/arm/kexec-zImage-arm.c
+++ b/kexec/arch/arm/kexec-zImage-arm.c
@@ -362,11 +362,10 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
if (dtb_file) {
dtb_buf = slurp_file(dtb_file, &dtb_length);
- extra_size = _ALIGN(dtb_length, getpagesize());
- } else if (use_atags) {
- extra_size = 0x8000; /* 32k should be plenty for ATAGs */
}
+ extra_size = 0x8000;
+
/*
* If we are loading a dump capture kernel, we need to update kernel
* command line and also add some additional segments.
@@ -460,6 +459,32 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
create_flatten_tree(&dtb_buf, &dtb_length, command_line);
}
+ /*
+ * Search in memory to make sure there is enough memory
+ * to hold initrd and dtb.
+ *
+ * Even if no initrd is used, this check is still
+ * required for dtb.
+ *
+ * Crash kernel use fixed address, no check is ok.
+ */
+ if ((info->kexec_flags & KEXEC_ON_CRASH) == 0) {
+ unsigned long page_size = getpagesize();
+ /*
+ * DTB size may be increase a little
+ * when setup initrd size. Add a full page
+ * for it is enough.
+ */
+ unsigned long hole_size = _ALIGN_UP(initrd_size, page_size) +
+ _ALIGN(dtb_length + page_size, page_size);
+ unsigned long initrd_base_new = locate_hole(info,
+ hole_size, page_size,
+ initrd_base, ULONG_MAX, INT_MAX);
+ if (base == ULONG_MAX)
+ return -1;
+ initrd_base = initrd_base_new;
+ }
+
if (ramdisk) {
add_segment(info, ramdisk_buf, initrd_size,
initrd_base, initrd_size);
--
1.8.4
