Re: [PATCH v2 00/15] powerpc/32s: Use BATs/LTLBs for STRICT_KERNEL_RWX

Le 16/01/2019 à 14:16, Jonathan Neuschäfer a écrit :

On Wed, Jan 16, 2019 at 07:55:29AM +0100, Christophe Leroy wrote:

quoted

Le 16/01/2019 à 01:35, Jonathan Neuschäfer a écrit :

quoted

Thinning the kernel down a bit actually makes it boot again. Ooops...!
Maybe enabling CONFIG_STRICT_KERNEL_RWX has made it just large enough to
fail the hash table allocation, but there may have been other factors
involved (I'm not sure exactly).  Sorry for the confusion!

Ok, that must be the reason. Thanks for testing.

What about the following modification which maps a second 256Mb BAT, does it
helps ?

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index c2f564690778..ea574596de37 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S

@@ -1160,6 +1160,14 @@ initial_bats:
  	mtspr	SPRN_DBAT0U,r11		/* bit in upper BAT register */
  	mtspr	SPRN_IBAT0L,r8
  	mtspr	SPRN_IBAT0U,r11
+#ifdef CONFIG_WII
+	addis	r11,r11,0x10000000@h
+	addis	r8,r8,0x10000000@h
+	mtspr	SPRN_DBAT2L,r8
+	mtspr	SPRN_DBAT2U,r11
+	mtspr	SPRN_IBAT2L,r8
+	mtspr	SPRN_IBAT2U,r11
+#endif
  	isync
  	blr

diff --git a/arch/powerpc/mm/ppc_mmu_32.c b/arch/powerpc/mm/ppc_mmu_32.c
index 3f4193201ee7..a334fd5210a8 100644
--- a/arch/powerpc/mm/ppc_mmu_32.c
+++ b/arch/powerpc/mm/ppc_mmu_32.c

@@ -259,6 +259,8 @@ void setup_initial_memory_limit(phys_addr_t

first_memblock_base,
  	/* 601 can only access 16MB at the moment */
  	if (PVR_VER(mfspr(SPRN_PVR)) == 1)
  		memblock_set_current_limit(min_t(u64, first_memblock_size, 0x01000000));
+	else if (IS_ENABLED(CONFIG_WII))
+		memblock_set_current_limit(min_t(u64, first_memblock_size, 0x20000000));
  	else /* Anything else has 256M mapped */
  		memblock_set_current_limit(min_t(u64, first_memblock_size, 0x10000000));
  }

I haven't tested it, but this patch won't be enough, because we're only
looking at the first memblock, and the additional memory in the Wii
(MEM2) is the second memblock.

Yes right.


Would the following work instead ?

memblock_set_current_limit(0x20000000);


Christophe