Overlayfs uses backing files with "fake" overlayfs f_path and "real" underlying f_inode, in order to use underlying inode aops for mapped files and to display the overlayfs path in /proc/<pid>/maps. In preparation for storing the overlayfs "fake" path instead of the underlying "real" path in struct backing_file, define a noop helper file_user_path() that returns f_path for now. Use the new helper in procfs and kernel logs whenever a path of a mapped file is displayed to users. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Link: https://lore.kernel.org/r/20231009153712.1566422-3-amir73il@gmail.com Signed-off-by: Christian Brauner <brauner@kernel.org>
Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202308221549.XKufWEWp-lkp@intel.com/ Signed-off-by: Vineet Gupta <vgupta@kernel.org>
Reduces duplication in each ISA specific pt_regs Tested-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202308151342.ROQ9Urvv-lkp@intel.com Signed-off-by: Vineet Gupta <vgupta@kernel.org>
Instead of r26,fp,sp,r12,r30 order as fp,r30,r12,r26,sp - keeps SP at well known position (right abive hardware autosave) - r26,r12 saved specifically for ARCv2 (and not in ARCv3) kept closer for easy ifdef'ry later Signed-off-by: Vineet Gupta <vgupta@kernel.org>
THe high level structure of most ARC exception handlers is 1. save regfile with EXCEPTION_PROLOGUE 2. setup r0: EFA (not part of pt_regs) 3. setup r1: pointer to pt_regs (SP) 4. drop down to pure kernel mode (from exception) 5. call the Linux "C" handler Remove the boiler plate code by moving #2, #3, #4 into #1. The exceptions to most exceptions are syscall Trap and Machine check which don't do some of above for various reasons, so call a newly introduced variant EXCEPTION_PROLOGUE_KEEP_AE (same as original EXCEPTION_PROLOGUE) Tested-by: Pavel Kozlov <Pavel.Kozlov@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@kernel.org>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
- comments update - rename syscall_trace_entry - use PT_xxx in entry code Signed-off-by: Vineet Gupta <vgupta@kernel.org>
task's arch specific bits are carried in 2 places - embedded thread_struct in task_struct - associated thread_info (hoisted in task's stack page) and syntactically: (thread_info *)(task_struct->stack) ksp (dynamic kernel stack top) currently lives in thread_struct but given its deep location in task struct likely to cache miss when accessed from __switch_to(). Moving it to thread_info would be more efficient given proximity to frequently accessed items such as preempt_count thus very likely to be in cache, specially in schedular code. Note however that currently tsk.thread.ksp takes 1 memory access (off of tsk pointer) while new code tsk->stack.ksp would take 2, but likely to be in cache. Moreover if task is current the 2nd reference can be elided and instead derived from SP as (SP & ~(THREAD_SIZE - 1)) All of this also makes __switch_to() code simpler and we can see the 2 ways of retirving ksp (descrobed above) in new code. Signed-off-by: Vineet Gupta <vgupta@kernel.org>
__switch_to() is final step of context switch, swapping kernel modes stack (and callee regs) of outgoing task with next task. It is also the starting point of stack unwinging of a sleeping task and captures SP, FP, BLINK and the corresponding dwarf info. Back when dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and gcc was responsible for generating dwarf info. Thus it had to be written in "C" with inline asm to do the hand crafting of stack. The function prologue (and crucial saving of blink etc) was still gcc generated but not visible in code. Likewise dwarf info was missing. Now with modern tools, we can make things more obvious by writing the code in asm and adding approproate dwarf cfi pseudo ops. This is mostly non functional change, except for slight chnages to asm - ARCompact doesn't support MOV_S fp, sp, so we use MOV Signed-off-by: Vineet Gupta <vgupta@kernel.org>