Messages in this thread | | | Subject | Re: [PATCH v13 00/10] powerpc: Switch to CONFIG_THREAD_INFO_IN_TASK | From | Christophe Leroy <> | Date | Wed, 23 Jan 2019 11:04:16 +0100 |
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Le 12/01/2019 à 10:55, Christophe Leroy a écrit : > The purpose of this serie is to activate 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.
I ran null_syscall and context_switch benchmark selftests and the result is surprising. There is slight degradation in context_switch and a significant one on null_syscall:
Without the serie:
~# chrt -f 98 ./context_switch --no-altivec --no-vector --no-fp 55542 55562 55564 55562 55568 ...
~# ./null_syscall 2546.71 ns 336.17 cycles
With the serie:
~# chrt -f 98 ./context_switch --no-altivec --no-vector --no-fp 55138 55142 55152 55144 55142
~# ./null_syscall 3479.54 ns 459.30 cycles
So 0,8% less context switches per second and 37% more time for one syscall ?
Any idea ?
Christophe
> > Changes since v12: > - Patch 1: Taken comment from Mike (re-introduced the 'panic' in case memblock allocation fails in setup_64.c > - Patch 1: Added alloc_stack() function in setup_32.c to also panic in case of allocation failure. > > Changes since v11: > - Rebased on 81775f5563fa ("Automatic merge of branches 'master', 'next' and 'fixes' into merge") > - Added a first patch to change memblock allocs to functions returning virtual addrs. This removes > the memset() which were the only remaining stuff in irq_ctx_init() and exc_lvl_ctx_init() at the end. > - dropping irq_ctx_init() and exc_lvl_ctx_init() in patch 5 (powerpc: Activate CONFIG_THREAD_INFO_IN_TASK) > - A few cosmetic changes in commit log and code. > > Changes since v10: > - Rebased on 21622a0d2023 ("Automatic merge of branches 'master', 'next' and 'fixes' into merge") > ==> Fixed conflict in setup_32.S > > Changes since v9: > - Rebased on 183cbf93be88 ("Automatic merge of branches 'master', 'next' and 'fixes' into merge") > ==> Fixed conflict on xmon > > Changes since v8: > - Rebased on e589b79e40d9 ("Automatic merge of branches 'master', 'next' and 'fixes' into merge") > ==> Main impact was conflicts due to commit 9a8dd708d547 ("memblock: rename memblock_alloc{_nid,_try_nid} to memblock_phys_alloc*") > > Changes since v7: > - Rebased on fb6c6ce7907d ("Automatic merge of branches 'master', 'next' and 'fixes' into merge") > > Changes since v6: > - Fixed validate_sp() to exclude NULL sp in 'regain entire stack space' patch (early crash with CONFIG_KMEMLEAK) > > Changes since v5: > - Fixed livepatch_sp setup by using end_of_stack() instead of hardcoding > - Fixed PPC_BPF_LOAD_CPU() macro > > Changes since v4: > - Fixed a build failure on 32bits SMP when include/generated/asm-offsets.h is not > already existing, was due to spaces instead of a tab in the Makefile > > Changes since RFC v3: (based on Nick's review) > - Renamed task_size.h to task_size_user64.h to better relate to what it contains. > - Handling of the isolation of thread_info cpu field inside CONFIG_SMP #ifdefs moved to a separate patch. > - Removed CURRENT_THREAD_INFO macro completely. > - Added a guard in asm/smp.h to avoid build failure before _TASK_CPU is defined. > - Added a patch at the end to rename 'tp' pointers to 'sp' pointers > - Renamed 'tp' into 'sp' pointers in preparation patch when relevant > - Fixed a few commit logs > - Fixed checkpatch report. > > Changes since RFC v2: > - Removed the modification of names in asm-offsets > - Created a rule in arch/powerpc/Makefile to append the offset of current->cpu in CFLAGS > - Modified asm/smp.h to use the offset set in CFLAGS > - Squashed the renaming of THREAD_INFO to TASK_STACK in the preparation patch > - Moved the modification of current_pt_regs in the patch activating CONFIG_THREAD_INFO_IN_TASK > > Changes since RFC v1: > - Removed the first patch which was modifying header inclusion order in timer > - Modified some names in asm-offsets to avoid conflicts when including asm-offsets in C files > - Modified asm/smp.h to avoid having to include linux/sched.h (using asm-offsets instead) > - Moved some changes from the activation patch to the preparation patch. > > Christophe Leroy (10): > powerpc/irq: use memblock functions returning virtual address > book3s/64: avoid circular header inclusion in mmu-hash.h > powerpc: Only use task_struct 'cpu' field on SMP > powerpc: Prepare for moving thread_info into task_struct > powerpc: Activate CONFIG_THREAD_INFO_IN_TASK > powerpc: regain entire stack space > powerpc: 'current_set' is now a table of task_struct pointers > powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU > powerpc/64: Remove CURRENT_THREAD_INFO > powerpc: clean stack pointers naming > > arch/powerpc/Kconfig | 1 + > arch/powerpc/Makefile | 7 ++ > arch/powerpc/include/asm/asm-prototypes.h | 4 +- > arch/powerpc/include/asm/book3s/64/mmu-hash.h | 2 +- > arch/powerpc/include/asm/exception-64s.h | 4 +- > arch/powerpc/include/asm/irq.h | 18 ++-- > arch/powerpc/include/asm/livepatch.h | 6 +- > arch/powerpc/include/asm/processor.h | 39 +-------- > arch/powerpc/include/asm/ptrace.h | 2 +- > arch/powerpc/include/asm/reg.h | 2 +- > arch/powerpc/include/asm/smp.h | 17 +++- > arch/powerpc/include/asm/task_size_user64.h | 42 +++++++++ > arch/powerpc/include/asm/thread_info.h | 19 ----- > arch/powerpc/kernel/asm-offsets.c | 10 ++- > arch/powerpc/kernel/entry_32.S | 66 +++++--------- > arch/powerpc/kernel/entry_64.S | 12 +-- > arch/powerpc/kernel/epapr_hcalls.S | 5 +- > arch/powerpc/kernel/exceptions-64e.S | 13 +-- > arch/powerpc/kernel/exceptions-64s.S | 2 +- > arch/powerpc/kernel/head_32.S | 14 +-- > arch/powerpc/kernel/head_40x.S | 4 +- > arch/powerpc/kernel/head_44x.S | 8 +- > arch/powerpc/kernel/head_64.S | 1 + > arch/powerpc/kernel/head_8xx.S | 2 +- > arch/powerpc/kernel/head_booke.h | 12 +-- > arch/powerpc/kernel/head_fsl_booke.S | 16 ++-- > arch/powerpc/kernel/idle_6xx.S | 8 +- > arch/powerpc/kernel/idle_book3e.S | 2 +- > arch/powerpc/kernel/idle_e500.S | 8 +- > arch/powerpc/kernel/idle_power4.S | 2 +- > arch/powerpc/kernel/irq.c | 114 +++---------------------- > arch/powerpc/kernel/kgdb.c | 28 ------ > arch/powerpc/kernel/machine_kexec_64.c | 6 +- > arch/powerpc/kernel/misc_32.S | 17 ++-- > arch/powerpc/kernel/process.c | 40 ++++----- > arch/powerpc/kernel/setup-common.c | 2 +- > arch/powerpc/kernel/setup_32.c | 25 +++--- > arch/powerpc/kernel/setup_64.c | 51 +++-------- > arch/powerpc/kernel/smp.c | 16 ++-- > arch/powerpc/kernel/trace/ftrace_64_mprofile.S | 6 +- > arch/powerpc/kvm/book3s_hv_hmi.c | 1 + > arch/powerpc/mm/hash_low_32.S | 14 ++- > arch/powerpc/net/bpf_jit32.h | 5 +- > arch/powerpc/sysdev/6xx-suspend.S | 5 +- > arch/powerpc/xmon/xmon.c | 2 +- > 45 files changed, 249 insertions(+), 431 deletions(-) > create mode 100644 arch/powerpc/include/asm/task_size_user64.h >
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