From c65eacbe290b8141554c71b2c94489e73ade8c8d Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 13 Sep 2016 14:29:24 -0700 Subject: sched/core: Allow putting thread_info into task_struct If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT, then thread_info is defined as a single 'u32 flags' and is the first entry of task_struct. thread_info::task is removed (it serves no purpose if thread_info is embedded in task_struct), and thread_info::cpu gets its own slot in task_struct. This is heavily based on a patch written by Linus. Originally-from: Linus Torvalds Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar --- include/linux/thread_info.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/linux/thread_info.h') diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 2b5b10eed74f..e2d0fd81b1ba 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -13,6 +13,21 @@ struct timespec; struct compat_timespec; +#ifdef CONFIG_THREAD_INFO_IN_TASK +struct thread_info { + u32 flags; /* low level flags */ +}; + +#define INIT_THREAD_INFO(tsk) \ +{ \ + .flags = 0, \ +} +#endif + +#ifdef CONFIG_THREAD_INFO_IN_TASK +#define current_thread_info() ((struct thread_info *)current) +#endif + /* * System call restart block. */ -- cgit v1.2.3 From 907241dccb4ce5d9413cf3c030b32b0cfc184914 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Fri, 23 Sep 2016 18:24:07 +0100 Subject: thread_info: Use unsigned long for flags The generic THREAD_INFO_IN_TASK definition of thread_info::flags is a u32, matching x86 prior to the introduction of THREAD_INFO_IN_TASK. However, common helpers like test_ti_thread_flag() implicitly assume that thread_info::flags has at least the size and alignment of unsigned long, and relying on padding and alignment provided by other elements of task_struct is somewhat fragile. Additionally, some architectures use more that 32 bits for thread_info::flags, and others may need to in future. With THREAD_INFO_IN_TASK, task struct follows thread_info with a long field, and thus we no longer save any space as we did back in commit: affa219b60a11b32 ("x86: change thread_info's flag field back to 32 bits") Given all this, it makes more sense for the generic thread_info::flags to be an unsigned long. In fact given contains/uses the helpers mentioned above, BE arches *must* use unsigned long (or something of the same size) today, or they wouldn't work. Make it so. Signed-off-by: Mark Rutland Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Kees Cook Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1474651447-30447-1-git-send-email-mark.rutland@arm.com Signed-off-by: Ingo Molnar --- include/linux/thread_info.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/thread_info.h') diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index e2d0fd81b1ba..45f004e9cc59 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -15,7 +15,7 @@ struct compat_timespec; #ifdef CONFIG_THREAD_INFO_IN_TASK struct thread_info { - u32 flags; /* low level flags */ + unsigned long flags; /* low level flags */ }; #define INIT_THREAD_INFO(tsk) \ -- cgit v1.2.3