On 2019/7/29 19:08, Christophe Leroy wrote:

Le 17/07/2019 à 10:06, Jason Yan a écrit :

quoted

Add a new helper reloc_kernel_entry() to jump back to the start of the
new kernel. After we put the new kernel in a randomized place we can use
this new helper to enter the kernel and begin to relocate again.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Cc: Diana Craciun <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <redacted>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <redacted>
---
  arch/powerpc/kernel/head_fsl_booke.S | 16 ++++++++++++++++
  arch/powerpc/mm/mmu_decl.h           |  1 +
  2 files changed, 17 insertions(+)

diff --git a/arch/powerpc/kernel/head_fsl_booke.S 

b/arch/powerpc/kernel/head_fsl_booke.S
index a57d44638031..ce40f96dae20 100644

--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S

@@ -1144,6 +1144,22 @@ _GLOBAL(create_tlb_entry)

      sync
      blr
+/*
+ * Return to the start of the relocated kernel and run again
+ * r3 - virtual address of fdt
+ * r4 - entry of the kernel
+ */
+_GLOBAL(reloc_kernel_entry)
+    mfmsr    r7
+    li    r8,(MSR_IS | MSR_DS)
+    andc    r7,r7,r8

Instead of the li/andc, what about the following:

rlwinm r7, r7, 0, ~(MSR_IS | MSR_DS)

Good idea.

quoted

+
+    mtspr    SPRN_SRR0,r4
+    mtspr    SPRN_SRR1,r7
+    isync
+    sync
+    rfi

Are the isync/sync really necessary ? AFAIK, rfi is context synchronising.

I see some code with sync before rfi so I'm not sure. I will check this
and drop the isync/sync if it's true.

Thanks.

quoted

+
  /*
   * Create a tlb entry with the same effective and physical address as
   * the tlb entry used by the current running code. But set the TS to 1.

diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index d7737cf97cee..dae8e9177574 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h

@@ -143,6 +143,7 @@ extern void adjust_total_lowmem(void);

  extern int switch_to_as1(void);
  extern void restore_to_as0(int esel, int offset, void *dt_ptr, int 
bootcpu);
  extern void create_tlb_entry(phys_addr_t phys, unsigned long virt, 
int entry);
+extern void reloc_kernel_entry(void *fdt, int addr);

No new 'extern' please, see 
https://openpower.xyz/job/snowpatch/job/snowpatch-linux-checkpatch/8125//artifact/linux/checkpatch.log 

quoted

  #endif
  extern void loadcam_entry(unsigned int index);
  extern void loadcam_multi(int first_idx, int num, int tmp_idx);

Christophe

.