Le 28/08/2019 à 06:54, Scott Wood a écrit :
On Fri, Aug 09, 2019 at 06:07:54PM +0800, Jason Yan wrote:
This patch add support to boot kernel from places other than KERNELBASE.
Since CONFIG_RELOCATABLE has already supported, what we need to do is
map or copy kernel to a proper place and relocate. Freescale Book-E
parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1
entries are not suitable to map the kernel directly in a randomized
region, so we chose to copy the kernel to a proper place and restart to
relocate.
The offset of the kernel was not randomized yet(a fixed 64M is set). We
will randomize it in the next patch.
Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
Cc: Diana Craciun <diana.craciun@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Tested-by: Diana Craciun <diana.craciun@xxxxxxx>
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
arch/powerpc/Kconfig | 11 ++++
arch/powerpc/kernel/Makefile | 1 +
arch/powerpc/kernel/early_32.c | 2 +-
arch/powerpc/kernel/fsl_booke_entry_mapping.S | 17 +++--
arch/powerpc/kernel/head_fsl_booke.S | 13 +++-
arch/powerpc/kernel/kaslr_booke.c | 62 +++++++++++++++++++
arch/powerpc/mm/mmu_decl.h | 7 +++
arch/powerpc/mm/nohash/fsl_booke.c | 7 ++-
8 files changed, 105 insertions(+), 15 deletions(-)
create mode 100644 arch/powerpc/kernel/kaslr_booke.c
[...]
diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c
new file mode 100644
index 000000000000..f8dc60534ac1
--- /dev/null
+++ b/arch/powerpc/kernel/kaslr_booke.c
Shouldn't this go under arch/powerpc/mm/nohash?
+/*
+ * To see if we need to relocate the kernel to a random offset
+ * void *dt_ptr - address of the device tree
+ * phys_addr_t size - size of the first memory block
+ */
+notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
+{
+ unsigned long tlb_virt;
+ phys_addr_t tlb_phys;
+ unsigned long offset;
+ unsigned long kernel_sz;
+
+ kernel_sz = (unsigned long)_end - KERNELBASE;
Why KERNELBASE and not kernstart_addr?
+
+ offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
+
+ if (offset == 0)
+ return;
+
+ kernstart_virt_addr += offset;
+ kernstart_addr += offset;
+
+ is_second_reloc = 1;
+
+ if (offset >= SZ_64M) {
+ tlb_virt = round_down(kernstart_virt_addr, SZ_64M);
+ tlb_phys = round_down(kernstart_addr, SZ_64M);
If kernstart_addr wasn't 64M-aligned before adding offset, then "offset
= SZ_64M" is not necessarily going to detect when you've crossed a
mapping boundary.
+
+ /* Create kernel map to relocate in */
+ create_tlb_entry(tlb_phys, tlb_virt, 1);
+ }
+
+ /* Copy the kernel to it's new location and run */
+ memcpy((void *)kernstart_virt_addr, (void *)KERNELBASE, kernel_sz);
+
+ reloc_kernel_entry(dt_ptr, kernstart_virt_addr);
+}
After copying, call flush_icache_range() on the destination.
Function copy_and_flush() does the copy and the flush. I think it should
be used instead of memcpy() + flush_icache_range()
Christophe
