From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx> Subject: mm: provide a fallback for PAGE_KERNEL_RO for architectures Some architectures do not define certain PAGE_KERNEL_* flags, this is either because: a) The way to implement some of these flags is *not yet ported*, or b) The architecture *has no way* to describe them Over time we have accumulated a few PAGE_KERNEL_* fallback workarounds for architectures in the kernel which do not define them using *relatively safe* equivalents. Move these scattered fallback hacks into asm-generic. We start off with PAGE_KERNEL_RO using PAGE_KERNEL as a fallback. This has been in place on the firmware loader for years. Move the fallback into the respective asm-generic header. Link: http://lkml.kernel.org/r/20180510185507.2439-2-mcgrof@xxxxxxxxxx Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/base/firmware_loader/fallback.c | 5 ----- include/asm-generic/pgtable.h | 14 ++++++++++++++ 2 files changed, 14 insertions(+), 5 deletions(-) --- a/drivers/base/firmware_loader/fallback.c~mm-provide-a-fallback-for-page_kernel_ro-for-architectures +++ a/drivers/base/firmware_loader/fallback.c @@ -219,11 +219,6 @@ static ssize_t firmware_loading_show(str return sprintf(buf, "%d\n", loading); } -/* Some architectures don't have PAGE_KERNEL_RO */ -#ifndef PAGE_KERNEL_RO -#define PAGE_KERNEL_RO PAGE_KERNEL -#endif - /* one pages buffer should be mapped/unmapped only once */ static int map_fw_priv_pages(struct fw_priv *fw_priv) { --- a/include/asm-generic/pgtable.h~mm-provide-a-fallback-for-page_kernel_ro-for-architectures +++ a/include/asm-generic/pgtable.h @@ -1095,6 +1095,20 @@ static inline bool arch_has_pfn_modify_c } #endif /* !_HAVE_ARCH_PFN_MODIFY_ALLOWED */ +/* + * Architecture PAGE_KERNEL_* fallbacks + * + * Some architectures don't define certain PAGE_KERNEL_* flags. This is either + * because they really don't support them, or the port needs to be updated to + * reflect the required functionality. Below are a set of relatively safe + * fallbacks, as best effort, which we can count on in lieu of the architectures + * not defining them on their own yet. + */ + +#ifndef PAGE_KERNEL_RO +# define PAGE_KERNEL_RO PAGE_KERNEL +#endif + #endif /* !__ASSEMBLY__ */ #ifndef io_remap_pfn_range _
