Revert "arch: introduce set_direct_map_valid_noflush()"

Commit 0c6378a715 ("arch: introduce set_direct_map_valid_noflush()")
added set_direct_map_valid_noflush() to allow updating the direct map for
a physically contiguous range in execmem.

As Brendan recently pointed out [1], this API is confusing because on
arm64 it means that is sets VALID bit in ptes, while on other
architectures it is an analog of set_direct_map_default_noflush().

The only user of set_direct_map_valid_noflush() was execmem's ROX cache
freeing path and it was switched to utilize VM_FLUSH_RESET_PERMS for
resetting permissions of the direct map alias.

With the last user gone and with
set_direct_map_{invalid,default}_noflush() accepting number of pages as a
parameter, set_direct_map_valid_noflush() become a copy of
set_memory_valid() on arm64 and a duplicate of
set_direct_map_{invalid,default}_noflush() on other architecture, it is
safe to remove set_direct_map_valid_noflush().

Also drop a stale comment in arm64::__kernel_map_pages() that Linus
bothered to add when merging changes containing
set_direct_map_valid_noflush() to his tree.

This reverts commit 0c6378a715.

Link: https://lore.kernel.org/20260903-execmem-set-vm-perms-v0-2-v3-6-949b64a9f755@kernel.org
Link: https://lore.kernel.org/all/DJ69RCVRBO0Y.3JCYSW50IC4RC@linux.dev [1]
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Brendan Jackman <brendan.jackman@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@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: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>

arch/arm64/include/asm/set_memory.h

@@ -13,7 +13,6 @@ int set_memory_valid(unsigned long addr, int numpages, int enable);
 
 int set_direct_map_invalid_noflush(struct page *page, unsigned int numpages);
 int set_direct_map_default_noflush(struct page *page, unsigned int numpages);
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid);
 bool kernel_page_present(struct page *page);
 
 int set_memory_encrypted(unsigned long addr, int numpages);

arch/arm64/mm/pageattr.c

@@ -355,23 +355,7 @@ int realm_register_memory_enc_ops(void)
 	return arm64_mem_crypt_ops_register(&realm_crypt_ops);
 }
 
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
-{
-	unsigned long addr = (unsigned long)page_address(page);
-
-	if (!can_set_direct_map())
-		return 0;
-
-	return set_memory_valid(addr, nr, valid);
-}
-
 #ifdef CONFIG_DEBUG_PAGEALLOC
-/*
- * This is - apart from the return value - doing the same
- * thing as the new set_direct_map_valid_noflush() function.
- *
- * Unify? Explain the conceptual differences?
- */
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	if (!can_set_direct_map())

arch/loongarch/include/asm/set_memory.h

@@ -17,6 +17,5 @@ int set_memory_rw(unsigned long addr, int numpages);
 bool kernel_page_present(struct page *page);
 int set_direct_map_default_noflush(struct page *page, unsigned int nr);
 int set_direct_map_invalid_noflush(struct page *page, unsigned int nr);
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid);
 
 #endif /* _ASM_LOONGARCH_SET_MEMORY_H */

arch/loongarch/mm/pageattr.c

@@ -217,22 +217,3 @@ int set_direct_map_invalid_noflush(struct page *page, unsigned int nr)
 
 	return __set_memory(addr, nr, __pgprot(0), __pgprot(_PAGE_PRESENT | _PAGE_VALID));
 }
-
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
-{
-	unsigned long addr = (unsigned long)page_address(page);
-	pgprot_t set, clear;
-
-	if (addr < vm_map_base)
-		return 0;
-
-	if (valid) {
-		set = PAGE_KERNEL;
-		clear = __pgprot(0);
-	} else {
-		set = __pgprot(0);
-		clear = __pgprot(_PAGE_PRESENT | _PAGE_VALID);
-	}
-
-	return __set_memory(addr, nr, set, clear);
-}

arch/riscv/include/asm/set_memory.h

@@ -42,7 +42,6 @@ static inline int set_kernel_memory(char *startp, char *endp,
 
 int set_direct_map_invalid_noflush(struct page *page, unsigned int nr);
 int set_direct_map_default_noflush(struct page *page, unsigned int nr);
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid);
 bool kernel_page_present(struct page *page);
 
 #endif /* __ASSEMBLER__ */

arch/riscv/mm/pageattr.c

@@ -386,21 +386,6 @@ int set_direct_map_default_noflush(struct page *page, unsigned int nr)
 			    PAGE_KERNEL, __pgprot(_PAGE_EXEC));
 }
 
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
-{
-	pgprot_t set, clear;
-
-	if (valid) {
-		set = PAGE_KERNEL;
-		clear = __pgprot(_PAGE_EXEC);
-	} else {
-		set = __pgprot(0);
-		clear = __pgprot(_PAGE_PRESENT);
-	}
-
-	return __set_memory((unsigned long)page_address(page), nr, set, clear);
-}
-
 #ifdef CONFIG_DEBUG_PAGEALLOC
 static int debug_pagealloc_set_page(pte_t *pte, unsigned long addr, void *data)
 {

arch/s390/include/asm/set_memory.h

@@ -62,7 +62,6 @@ __SET_MEMORY_FUNC(set_memory_4k, SET_MEMORY_4K)
 
 int set_direct_map_invalid_noflush(struct page *page, unsigned int nr);
 int set_direct_map_default_noflush(struct page *page, unsigned int nr);
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid);
 bool kernel_page_present(struct page *page);
 
 #endif

arch/s390/mm/pageattr.c

@@ -392,18 +392,6 @@ int set_direct_map_default_noflush(struct page *page, unsigned int nr)
 	return __set_memory((unsigned long)page_to_virt(page), nr, SET_MEMORY_DEF);
 }
 
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
-{
-	unsigned long flags;
-
-	if (valid)
-		flags = SET_MEMORY_DEF;
-	else
-		flags = SET_MEMORY_INV;
-
-	return __set_memory((unsigned long)page_to_virt(page), nr, flags);
-}
-
 bool kernel_page_present(struct page *page)
 {
 	unsigned long addr;

arch/x86/include/asm/set_memory.h

@@ -88,7 +88,6 @@ int set_pages_rw(struct page *page, int numpages);
 
 int set_direct_map_invalid_noflush(struct page *page, unsigned int nr);
 int set_direct_map_default_noflush(struct page *page, unsigned int nr);
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid);
 bool kernel_page_present(struct page *page);
 
 extern int kernel_set_to_readonly;

arch/x86/mm/pat/set_memory.c

@@ -2695,14 +2695,6 @@ int set_direct_map_default_noflush(struct page *page, unsigned int nr)
 	return __set_pages_p(page, nr, 0);
 }
 
-int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
-{
-	if (valid)
-		return __set_pages_p(page, nr, 0);
-
-	return __set_pages_np(page, nr, 0);
-}
-
 #ifdef CONFIG_DEBUG_PAGEALLOC
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {

include/linux/set_memory.h

@@ -36,12 +36,6 @@ static inline int set_direct_map_default_noflush(struct page *page,
 	return 0;
 }
 
-static inline int set_direct_map_valid_noflush(struct page *page,
-					       unsigned nr, bool valid)
-{
-	return 0;
-}
-
 static inline bool kernel_page_present(struct page *page)
 {
 	return true;