[PATCH 1/2] powerpc/32: Call mmu_mark_initmem_nx() regardless of data block mapping.

[PATCH 1/2] powerpc/32: Call mmu_mark_initmem_nx() regardless of data block mapping.

[Christophe Leroy]

mark_initmem_nx() calls either mmu_mark_initmem_nx() or
set_memory_attr() based on return from v_block_mapped()
of _sinittext.

But we can now handle text and data independently, so that
text may be mapped by block even when data is mapped by pages.

On the 8xx for instance, at startup 32Mbytes of memory are
pinned in TLB. So the pinned entries need to go away for sinittext.

In next patch a BAT will be set to also covers sinittext on book3s/32.
So it will also be needed to call mmu_mark_initmem_nx() even when
data above sinittext is not mapped with BATs.

As this is highly dependent on the platform, call mmu_mark_initmem_nx()
regardless of data block mapping. Then the platform will know what to
do.

Modify 8xx mmu_mark_initmem_nx() so that inittext mapping is modified
only when pagealloc debug and kfence are not active, otherwise inittext
is mapped with standard pages. And don't do anything on kernel text
which is already mapped with PAGE_KERNEL_TEXT.

Cc: Maxime Bizon <mbizon@freebox.fr>
Fixes: da1adea07576 ("powerpc/8xx: Allow STRICT_KERNEL_RwX with pinned TLB")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/nohash/8xx.c | 4 ++--
 arch/powerpc/mm/pgtable_32.c | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index 27f9186ae374..1ee08c3efe5b 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -179,8 +179,8 @@ void mmu_mark_initmem_nx(void)
 	unsigned long boundary = strict_kernel_rwx_enabled() ? sinittext : etext8;
 	unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);
 
-	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
-	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
+	if (!debug_pagealloc_enabled_or_kfence())
+		mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
 
 	mmu_pin_tlb(block_mapped_ram, false);
 }
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index a56ade39dc68..3ac73f9fb5d5 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -135,9 +135,9 @@ void mark_initmem_nx(void)
 	unsigned long numpages = PFN_UP((unsigned long)_einittext) -
 				 PFN_DOWN((unsigned long)_sinittext);
 
-	if (v_block_mapped((unsigned long)_sinittext)) {
-		mmu_mark_initmem_nx();
-	} else {
+	mmu_mark_initmem_nx();
+
+	if (!v_block_mapped((unsigned long)_sinittext)) {
 		set_memory_nx((unsigned long)_sinittext, numpages);
 		set_memory_rw((unsigned long)_sinittext, numpages);
 	}
-- 
2.36.1

[PATCH 2/2] powerpc/32: Set an IBAT covering up to _einittext during init

[Christophe Leroy]

Always set an IBAT covering up to _einittext during init because when
CONFIG_MODULES is not selected there is no reason to have an exception
handler for kernel instruction TLB misses.

It implies DBAT and IBAT are now totaly independent, IBATs are set
by setibat() and DBAT by setbat().

This allows to revert commit 9bb162fa26ed ("powerpc/603: Fix
boot failure with DEBUG_PAGEALLOC and KFENCE")

Reported-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_book3s_32.S |  4 ++--
 arch/powerpc/mm/book3s32/mmu.c       | 10 ++++------
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 6c739beb938c..519b60695167 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -418,14 +418,14 @@ InstructionTLBMiss:
  */
 	/* Get PTE (linux-style) and check access */
 	mfspr	r3,SPRN_IMISS
-#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
+#ifdef CONFIG_MODULES
 	lis	r1, TASK_SIZE@h		/* check if kernel address */
 	cmplw	0,r1,r3
 #endif
 	mfspr	r2, SPRN_SDR1
 	li	r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC | _PAGE_USER
 	rlwinm	r2, r2, 28, 0xfffff000
-#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
+#ifdef CONFIG_MODULES
 	bgt-	112f
 	lis	r2, (swapper_pg_dir - PAGE_OFFSET)@ha	/* if kernel address, use */
 	li	r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index 49a737fbbd18..40029280c320 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -159,7 +159,10 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 {
 	unsigned long done;
 	unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;
+	unsigned long size;
 
+	size = roundup_pow_of_two((unsigned long)_einittext - PAGE_OFFSET);
+	setibat(0, PAGE_OFFSET, 0, size, PAGE_KERNEL_X);
 
 	if (debug_pagealloc_enabled_or_kfence() || __map_without_bats) {
 		pr_debug_once("Read-Write memory mapped without BATs\n");
@@ -245,10 +248,9 @@ void mmu_mark_rodata_ro(void)
 }
 
 /*
- * Set up one of the I/D BAT (block address translation) register pairs.
+ * Set up one of the D BAT (block address translation) register pairs.
  * The parameters are not checked; in particular size must be a power
  * of 2 between 128k and 256M.
- * On 603+, only set IBAT when _PAGE_EXEC is set
  */
 void __init setbat(int index, unsigned long virt, phys_addr_t phys,
 		   unsigned int size, pgprot_t prot)
@@ -284,10 +286,6 @@ void __init setbat(int index, unsigned long virt, phys_addr_t phys,
 		/* G bit must be zero in IBATs */
 		flags &= ~_PAGE_EXEC;
 	}
-	if (flags & _PAGE_EXEC)
-		bat[0] = bat[1];
-	else
-		bat[0].batu = bat[0].batl = 0;
 
 	bat_addrs[index].start = virt;
 	bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1;
-- 
2.36.1

Re: [PATCH 1/2] powerpc/32: Call mmu_mark_initmem_nx() regardless of data block mapping.

[Michael Ellerman]

On Tue, 14 Jun 2022 12:34:08 +0200, Christophe Leroy wrote:
> mark_initmem_nx() calls either mmu_mark_initmem_nx() or
> set_memory_attr() based on return from v_block_mapped()
> of _sinittext.
> 
> But we can now handle text and data independently, so that
> text may be mapped by block even when data is mapped by pages.
> 
> [...]

Applied to powerpc/next.

[1/2] powerpc/32: Call mmu_mark_initmem_nx() regardless of data block mapping.
      https://git.kernel.org/powerpc/c/980bbf7ca72012d317617fcdbfabe8708e4cef29
[2/2] powerpc/32: Set an IBAT covering up to _einittext during init
      https://git.kernel.org/powerpc/c/2a0fb3c155c97c75176e557d61f8e66c1bd9b735

cheers