Re: [PATCH v1 1/8] powerpc/32s: Always map kernel text and rodata with BATs

[Michael Ellerman]

On Wed, 25 Nov 2020 07:10:46 + (UTC), Christophe Leroy wrote:
> Since commit 2b279c0348af ("powerpc/32s: Allow mapping with BATs with
> DEBUG_PAGEALLOC"), there is no real situation where mapping without
> BATs is required.
> 
> In order to simplify memory handling, always map kernel text
> and rodata with BATs even when "nobats" kernel parameter is set.
> 
> [...]

Applied to powerpc/next.

[1/8] powerpc/32s: Always map kernel text and rodata with BATs
  https://git.kernel.org/powerpc/c/035b19a15a98907916a42a6b1d025877c42f10ad
[2/8] powerpc/32s: Don't hash_preload() kernel text
  https://git.kernel.org/powerpc/c/79d1befe054ad4adb277fbd2d2756b1394eaf24e
[3/8] powerpc/32s: Fix an FTR_SECTION_ELSE
  https://git.kernel.org/powerpc/c/7b107a71e732c298d684ee1bafd82f1a2be58d5e
[4/8] powerpc/32s: Don't use SPRN_SPRG_PGDIR in hash_page
  https://git.kernel.org/powerpc/c/03d701c2d9b0091cf8e96cb49ab7d2a6a9f19937
[5/8] powerpc/603: Use SPRN_SDR1 to store the pgdir phys address
  https://git.kernel.org/powerpc/c/c4a22611bf6ced73d86bdfc0604d7db8982a24a4
[6/8] powerpc/32: Simplify EXCEPTION_PROLOG_1 macro
  https://git.kernel.org/powerpc/c/6285f9cff570bfd07b542840912c1d01bd5428e0
[7/8] powerpc/32s: Use SPRN_SPRG_SCRATCH2 in DSI prolog
  https://git.kernel.org/powerpc/c/de1cd0790697e67b728de43e8657bb52f528bfb9
[8/8] powerpc/32: Use SPRN_SPRG_SCRATCH2 in exception prologs
  https://git.kernel.org/powerpc/c/d2e006036082e2dc394c5ec86c5bb88cc27c0749

cheers

[PATCH v1 1/8] powerpc/32s: Always map kernel text and rodata with BATs

[Christophe Leroy]

Since commit 2b279c0348af ("powerpc/32s: Allow mapping with BATs with
DEBUG_PAGEALLOC"), there is no real situation where mapping without
BATs is required.

In order to simplify memory handling, always map kernel text
and rodata with BATs even when "nobats" kernel parameter is set.

Also fix the 603 TLB miss exceptions that don't require anymore
kernel page table if DEBUG_PAGEALLOC.

Signed-off-by: Christophe Leroy 
---
 arch/powerpc/kernel/head_book3s_32.S | 4 ++--
 arch/powerpc/mm/book3s32/mmu.c   | 8 +++-
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kernel/head_book3s_32.S 
b/arch/powerpc/kernel/head_book3s_32.S
index a0dda2a1f2df..27767f3e7ec1 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -453,13 +453,13 @@ InstructionTLBMiss:
  */
/* Get PTE (linux-style) and check access */
mfspr   r3,SPRN_IMISS
-#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC)
+#ifdef CONFIG_MODULES
lis r1, TASK_SIZE@h /* check if kernel address */
cmplw   0,r1,r3
 #endif
mfspr   r2, SPRN_SPRG_PGDIR
li  r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
-#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC)
+#ifdef CONFIG_MODULES
bgt-112f
lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha   /* if kernel address, 
use */
addir2, r2, (swapper_pg_dir - PAGE_OFFSET)@l/* kernel page 
table */
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index a59e7ec98180..5c60dcade90a 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -157,11 +157,9 @@ unsigned long __init mmu_mapin_ram(unsigned long base, 
unsigned long top)
unsigned long done;
unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;
 
-   if (__map_without_bats) {
-   pr_debug("RAM mapped without BATs\n");
-   return base;
-   }
-   if (debug_pagealloc_enabled()) {
+
+   if (debug_pagealloc_enabled() || __map_without_bats) {
+   pr_debug_once("Read-Write memory mapped without BATs\n");
if (base >= border)
return base;
if (top >= border)
-- 
2.25.0