Re: [PATCH v2 4/6] powerpc/pkeys: Preallocate execute-only key
From: Thiago Jung Bauermann <hidden>
Date: 2018-06-29 03:03:03
Hello, My understanding is that this patch isn't upstream yet and it's not too late for bikeshedding. Please ignore if this is not the case. Ram Pai [off-list ref] writes:
quoted hunk ↗ jump to hunk
@@ -326,48 +330,7 @@ static inline bool pkey_allows_readwrite(int pkey) int __execute_only_pkey(struct mm_struct *mm) { - bool need_to_set_mm_pkey = false; - int execute_only_pkey = mm->context.execute_only_pkey; - int ret; - - /* Do we need to assign a pkey for mm's execute-only maps? */ - if (execute_only_pkey == -1) { - /* Go allocate one to use, which might fail */ - execute_only_pkey = mm_pkey_alloc(mm); - if (execute_only_pkey < 0) - return -1; - need_to_set_mm_pkey = true; - } - - /* - * We do not want to go through the relatively costly dance to set AMR - * if we do not need to. Check it first and assume that if the - * execute-only pkey is readwrite-disabled than we do not have to set it - * ourselves. - */ - if (!need_to_set_mm_pkey && !pkey_allows_readwrite(execute_only_pkey)) - return execute_only_pkey; - - /* - * Set up AMR so that it denies access for everything other than - * execution. - */ - ret = __arch_set_user_pkey_access(current, execute_only_pkey, - PKEY_DISABLE_ACCESS | - PKEY_DISABLE_WRITE); - /* - * If the AMR-set operation failed somehow, just return 0 and - * effectively disable execute-only support. - */ - if (ret) { - mm_pkey_free(mm, execute_only_pkey); - return -1; - } - - /* We got one, store it and use it from here on out */ - if (need_to_set_mm_pkey) - mm->context.execute_only_pkey = execute_only_pkey; - return execute_only_pkey; + return mm->context.execute_only_pkey; }
There's no reason to have a separate __execute_only_pkey() function anymore. Its single line can go directly in execute_only_pkey(), defined in <asm/pkeys.h>. -- Thiago Jung Bauermann IBM Linux Technology Center