kernel/arch/powerpc/include/asm/thread_info.h, branch linux-5.2.y

powerpc/64: Replace CURRENT_THREAD_INFO with PACA_THREAD_INFO

2019-02-23T11:31:40Z

Now that current_thread_info is located at the beginning of 'current' task struct, CURRENT_THREAD_INFO macro is not really needed any more. This patch replaces it by loads of the value at PACA_THREAD_INFO(r13). Signed-off-by: Christophe Leroy [mpe: Add PACA_THREAD_INFO rather than using PACACURRENT] Signed-off-by: Michael Ellerman

powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU

2019-02-23T11:31:40Z

Now that thread_info is similar to task_struct, its address is in r2 so CURRENT_THREAD_INFO() macro is useless. This patch removes it. This patch also moves the 'tovirt(r2, r2)' down just before the reactivation of MMU translation, so that we keep the physical address of 'current' in r2 until then. It avoids a few calls to tophys(). At the same time, as the 'cpu' field is not anymore in thread_info, TI_CPU is renamed TASK_CPU by this patch. It also allows to get rid of a couple of '#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE' as ACCOUNT_CPU_USER_ENTRY() and ACCOUNT_CPU_USER_EXIT() are empty when CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not defined. Signed-off-by: Christophe Leroy [mpe: Fix a missed conversion of TI_CPU idle_6xx.S] Signed-off-by: Michael Ellerman

powerpc: Activate CONFIG_THREAD_INFO_IN_TASK

2019-02-23T11:31:40Z

This patch activates CONFIG_THREAD_INFO_IN_TASK which moves the thread_info into task_struct. Moving thread_info into task_struct has the following advantages: - It protects thread_info from corruption in the case of stack overflows. - Its address is harder to determine if stack addresses are leaked, making a number of attacks more difficult. This has the following consequences: - thread_info is now located at the beginning of task_struct. - The 'cpu' field is now in task_struct, and only exists when CONFIG_SMP is active. - thread_info doesn't have anymore the 'task' field. This patch: - Removes all recopy of thread_info struct when the stack changes. - Changes the CURRENT_THREAD_INFO() macro to point to current. - Selects CONFIG_THREAD_INFO_IN_TASK. - Modifies raw_smp_processor_id() to get ->cpu from current without including linux/sched.h to avoid circular inclusion and without including asm/asm-offsets.h to avoid symbol names duplication between ASM constants and C constants. - Modifies klp_init_thread_info() to take a task_struct pointer argument. Signed-off-by: Christophe Leroy Reviewed-by: Nicholas Piggin [mpe: Add task_stack.h to livepatch.h to fix build fails] Signed-off-by: Michael Ellerman

powerpc/64s/hash: Add a SLB preload cache

2018-10-14T07:04:09Z

When switching processes, currently all user SLBEs are cleared, and a few (exec_base, pc, and stack) are preloaded. In trivial testing with small apps, this tends to miss the heap and low 256MB segments, and it will also miss commonly accessed segments on large memory workloads. Add a simple round-robin preload cache that just inserts the last SLB miss into the head of the cache and preloads those at context switch time. Every 256 context switches, the oldest entry is removed from the cache to shrink the cache and require fewer slbmte if they are unused. Much more could go into this, including into the SLB entry reclaim side to track some LRU information etc, which would require a study of large memory workloads. But this is a simple thing we can do now that is an obvious win for common workloads. With the full series, process switching speed on the context_switch benchmark on POWER9/hash (with kernel speculation security masures disabled) increases from 140K/s to 178K/s (27%). POWER8 does not change much (within 1%), it's unclear why it does not see a big gain like POWER9. Booting to busybox init with 256MB segments has SLB misses go down from 945 to 69, and with 1T segments 900 to 21. These could almost all be eliminated by preloading a bit more carefully with ELF binary loading. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s/hash: Provide arch_setup_exec() hooks for hash slice setup

2018-10-14T07:04:09Z

This will be used by the SLB code in the next patch, but for now this sets the slb_addr_limit to the correct size for 32-bit tasks. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/ptrace: Add support for PTRACE_SYSEMU

2018-10-03T05:40:04Z

This is a patch that adds support for PTRACE_SYSEMU ptrace request in PowerPC architecture. When ptrace(PTRACE_SYSEMU, ...) request is called, it will be handled by the arch independent function ptrace_resume(), which will tag the task with the TIF_SYSCALL_EMU flag. This flag needs to be handled from a platform dependent point of view, which is what this patch does. This patch adds this task's flag as part of the _TIF_SYSCALL_DOTRACE, which is the MACRO that is used to trace syscalls at entrance/exit. Since TIF_SYSCALL_EMU is now part of _TIF_SYSCALL_DOTRACE, if the task has _TIF_SYSCALL_DOTRACE set, it will hit do_syscall_trace_enter() at syscall entrance and do_syscall_trace_leave() at syscall leave. do_syscall_trace_enter() needs to handle the TIF_SYSCALL_EMU flag properly, which will interrupt the syscall executing if TIF_SYSCALL_EMU is set. The output values should not be changed, i.e. the return value (r3) should contain the original syscall argument on exit. With this flag set, the syscall is not executed fundamentally, because do_syscall_trace_enter() is returning -1 which is bigger than NR_syscall, thus, skipping the syscall execution and exiting userspace. Signed-off-by: Breno Leitao Signed-off-by: Michael Ellerman

powerpc: Redefine TIF_32BITS thread flag

2018-10-03T05:40:04Z

Moving TIF_32BIT to use bit 20 instead of 4 in the task flag field. This change is making room for an upcoming new task macro (_TIF_SYSCALL_EMU) which is preferred to set a bit in the lower 16-bits part of the word. This upcoming flag macro will take part in a composed macro (_TIF_SYSCALL_DOTRACE) which will contain other flags as well, and it is preferred that the whole _TIF_SYSCALL_DOTRACE macro only sets the lower 16 bits of a word, so, it could be handled using immediate operations (as load immediate, add immediate, ...) where the immediate operand (SI) is limited to 16-bits. Another possible solution would be using the LOAD_REG_IMMEDIATE() macro to load a full 64-bits word immediate, but it takes 5 operations instead of one. Having TIF_32BITS being redefined to use an upper bit is not a problem since there is only one place in the assembly code where TIF_32BIT is being used, and it could be replaced with an operation with right shift (addis), since it is used alone, i.e. not being part of a composed macro, which has different bits set, and would require LOAD_REG_IMMEDIATE(). Tested on a 64 bits Big Endian machine running a 32 bits task. Signed-off-by: Breno Leitao Signed-off-by: Michael Ellerman

Revert "convert SLB miss handlers to C" and subsequent commits

2018-10-03T05:32:49Z

This reverts commits: 5e46e29e6a97 ("powerpc/64s/hash: convert SLB miss handlers to C") 8fed04d0f6ae ("powerpc/64s/hash: remove user SLB data from the paca") 655deecf67b2 ("powerpc/64s/hash: SLB allocation status bitmaps") 2e1626744e8d ("powerpc/64s/hash: provide arch_setup_exec hooks for hash slice setup") 89ca4e126a3f ("powerpc/64s/hash: Add a SLB preload cache") This series had a few bugs, and the fixes are not all trivial. So revert most of it for now. Signed-off-by: Michael Ellerman

powerpc/64s/hash: Add a SLB preload cache

2018-09-19T12:01:56Z

powerpc/64s/hash: provide arch_setup_exec hooks for hash slice setup

2018-09-19T12:01:56Z

This will be used by the SLB code in the next patch, but for now this sets the slb_addr_limit to the correct size for 32-bit tasks. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman