arm64, powerpc, riscv, s390, x86: ptdump: refactor CONFIG_DEBUG_WX

All architectures using the core ptdump functionality also implement
CONFIG_DEBUG_WX, and they all do it more or less the same way, with a
function called debug_checkwx() that is called by mark_rodata_ro(), which
is a substitute to ptdump_check_wx() when CONFIG_DEBUG_WX is set and a
no-op otherwise.

Refactor by centrally defining debug_checkwx() in linux/ptdump.h and call
debug_checkwx() immediately after calling mark_rodata_ro() instead of
calling it at the end of every mark_rodata_ro().

On x86_32, mark_rodata_ro() first checks __supported_pte_mask has _PAGE_NX
before calling debug_checkwx().  Now the check is inside the callee
ptdump_walk_pgd_level_checkwx().

On powerpc_64, mark_rodata_ro() bails out early before calling
ptdump_check_wx() when the MMU doesn't have KERNEL_RO feature.  The check
is now also done in ptdump_check_wx() as it is called outside
mark_rodata_ro().

Link: https://lkml.kernel.org/r/a59b102d7964261d31ead0316a9f18628e4e7a8e.1706610398.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg KH <greg@kroah.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Phong Tran <tranmanphong@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Price <steven.price@arm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

4 files changed, 3 insertions, 13 deletions

diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 72341b9fb552..90dcc2844056 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -171,12 +171,6 @@ static inline void mmu_mark_rodata_ro(void) { }
 void __init mmu_mapin_immr(void);
 #endif
 
-#ifdef CONFIG_DEBUG_WX
-void ptdump_check_wx(void);
-#else
-static inline void ptdump_check_wx(void) { }
-#endif
-
 static inline bool debug_pagealloc_enabled_or_kfence(void)
 {
 	return IS_ENABLED(CONFIG_KFENCE) || debug_pagealloc_enabled();
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 5c02fd08d61e..12498017da8e 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -153,7 +153,6 @@ void mark_rodata_ro(void)
 
 	if (v_block_mapped((unsigned long)_stext + 1)) {
 		mmu_mark_rodata_ro();
-		ptdump_check_wx();
 		return;
 	}
 
@@ -166,9 +165,6 @@ void mark_rodata_ro(void)
 		   PFN_DOWN((unsigned long)_stext);
 
 	set_memory_ro((unsigned long)_stext, numpages);
-
-	// mark_initmem_nx() should have already run by now
-	ptdump_check_wx();
 }
 #endif
 
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 5ac1fd30341b..1b366526f4f2 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -150,9 +150,6 @@ void mark_rodata_ro(void)
 		radix__mark_rodata_ro();
 	else
 		hash__mark_rodata_ro();
-
-	// mark_initmem_nx() should have already run by now
-	ptdump_check_wx();
 }
 
 void mark_initmem_nx(void)
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 2313053fe679..620d4917ebe8 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -343,6 +343,9 @@ void ptdump_check_wx(void)
 		}
 	};
 
+	if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && !mmu_has_feature(MMU_FTR_KERNEL_RO))
+		return;
+
 	ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 
 	if (st.wx_pages)