kernel/git/stable/linux.git/arch/csky, branch linux-5.7.y

csky: Fixup CONFIG_DEBUG_RSEQ

2020-05-28T00:18:36+00:00

Put the rseq_syscall check point at the prologue of the syscall will break the a0 ... a7. This will casue system call bug when DEBUG_RSEQ is enabled. So move it to the epilogue of syscall, but before syscall_trace. Signed-off-by: Guo Ren

csky: Coding convention in entry.S

2020-05-28T00:18:36+00:00

There is no fixup or feature in the patch, we only cleanup with: - Remove unnecessary reg used (r11, r12), just use r9 & r10 & syscallid regs as temp useage. - Add _TIF_SYSCALL_WORK and _TIF_WORK_MASK to gather macros. Signed-off-by: Guo Ren

csky: Fixup abiv2 syscall_trace break a4 & a5

2020-05-28T00:18:36+00:00

Current implementation could destory a4 & a5 when strace, so we need to get them from pt_regs by SAVE_ALL. Signed-off-by: Guo Ren

csky: Fixup CONFIG_PREEMPT panic

2020-05-28T00:18:36+00:00

log: [ 0.13373200] Calibrating delay loop... [ 0.14077600] ------------[ cut here ]------------ [ 0.14116700] WARNING: CPU: 0 PID: 0 at kernel/sched/core.c:3790 preempt_count_add+0xc8/0x11c [ 0.14348000] DEBUG_LOCKS_WARN_ON((preempt_count() < 0))Modules linked in: [ 0.14395100] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0 #7 [ 0.14410800] [ 0.14427400] Call Trace: [ 0.14450700] [<807cd226>] dump_stack+0x8a/0xe4 [ 0.14473500] [<80072792>] __warn+0x10e/0x15c [ 0.14495900] [<80072852>] warn_slowpath_fmt+0x72/0xc0 [ 0.14518600] [<800a5240>] preempt_count_add+0xc8/0x11c [ 0.14544900] [<807ef918>] _raw_spin_lock+0x28/0x68 [ 0.14572600] [<800e0eb8>] vprintk_emit+0x84/0x2d8 [ 0.14599000] [<800e113a>] vprintk_default+0x2e/0x44 [ 0.14625100] [<800e2042>] vprintk_func+0x12a/0x1d0 [ 0.14651300] [<800e1804>] printk+0x30/0x48 [ 0.14677600] [<80008052>] lockdep_init+0x12/0xb0 [ 0.14703800] [<80002080>] start_kernel+0x558/0x7f8 [ 0.14730000] [<800052bc>] csky_start+0x58/0x94 [ 0.14756600] irq event stamp: 34 [ 0.14775100] hardirqs last enabled at (33): [<80067370>] ret_from_exception+0x2c/0x72 [ 0.14793700] hardirqs last disabled at (34): [<800e0eae>] vprintk_emit+0x7a/0x2d8 [ 0.14812300] softirqs last enabled at (32): [<800655b0>] __do_softirq+0x578/0x6d8 [ 0.14830800] softirqs last disabled at (25): [<8007b3b8>] irq_exit+0xec/0x128 The preempt_count of reg could be destroyed after csky_do_IRQ without reload from memory. After reference to other architectures (arm64, riscv), we move preempt entry into ret_from_exception and disable irq at the beginning of ret_from_exception instead of RESTORE_ALL. Signed-off-by: Guo Ren Reported-by: Lu Baoquan

csky: Fixup raw_copy_from_user()

2020-05-14T16:16:30+00:00

If raw_copy_from_user(to, from, N) returns K, callers expect the first N - K bytes starting at to to have been replaced with the contents of corresponding area starting at from and the last K bytes of destination *left* *unmodified*. What arch/sky/lib/usercopy.c is doing is broken - it can lead to e.g. data corruption on write(2). raw_copy_to_user() is inaccurate about return value, which is a bug, but consequences are less drastic than for raw_copy_from_user(). And just what are those access_ok() doing in there? I mean, look into linux/uaccess.h; that's where we do that check (as well as zero tail on failure in the callers that need zeroing). AFAICS, all of that shouldn't be hard to fix; something like a patch below might make a useful starting point. I would suggest moving these macros into usercopy.c (they are never used anywhere else) and possibly expanding them there; if you leave them alive, please at least rename __copy_user_zeroing(). Again, it must not zero anything on failed read. Said that, I'm not sure we won't be better off simply turning usercopy.c into usercopy.S - all that is left there is a couple of functions, each consisting only of inline asm. Guo Ren reply: Yes, raw_copy_from_user is wrong, it's no need zeroing code. unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n) { unsigned long res = n; might_fault(); if (likely(access_ok(from, n))) { kasan_check_write(to, n); res = raw_copy_from_user(to, from, n); } if (unlikely(res)) memset(to + (n - res), 0, res); return res; } EXPORT_SYMBOL(_copy_from_user); You are right and access_ok() should be removed. but, how about: do { ... "2: stw %3, (%1, 0) \n" \ + " subi %0, 4 \n" \ "9: stw %4, (%1, 4) \n" \ + " subi %0, 4 \n" \ "10: stw %5, (%1, 8) \n" \ + " subi %0, 4 \n" \ "11: stw %6, (%1, 12) \n" \ + " subi %0, 4 \n" \ " addi %2, 16 \n" \ " addi %1, 16 \n" \ Don't expand __ex_table AI Viro reply: Hey, I've no idea about the instruction scheduling on csky - if that doesn't slow the things down, all the better. It's just that copy_to_user() and friends are on fairly hot codepaths, and in quite a few situations they will dominate the speed of e.g. read(2). So I tried to keep the fast path unchanged. Up to the architecture maintainers, obviously. Which would be you... As for the fixups size increase (__ex_table size is unchanged)... You have each of those macros expanded exactly once. So the size is not a serious argument, IMO - useless complexity would be, if it is, in fact, useless; the size... not really, especially since those extra subi will at least offset it. Again, up to you - asm optimizations of (essentially) memcpy()-style loops are tricky and can depend upon the fairly subtle details of architecture. So even on something I know reasonably well I would resort to direct experiments if I can't pass the buck to architecture maintainers. It *is* worth optimizing - this is where read() from a file that is already in page cache spends most of the time, etc. Guo Ren reply: Thx, after fixup some typo “sub %0, 4”, apply the patch. TODO: - user copy/from codes are still need optimizing. Signed-off-by: Al Viro Signed-off-by: Guo Ren

csky: Fixup gdbmacros.txt with name sp in thread_struct

2020-05-14T16:16:18+00:00

The gdbmacros.txt use sp in thread_struct, but csky use ksp. This cause bttnobp fail to excute. TODO: - Still couldn't display the contents of stack. Signed-off-by: Guo Ren

csky: Fixup remove unnecessary save/restore PSR code

2020-05-13T09:55:06+00:00

All processes' PSR could success from SETUP_MMU, so need set it in INIT_THREAD again. And use a3 instead of r7 in __switch_to for code convention. Signed-off-by: Guo Ren

csky: Fixup remove duplicate irq_disable

2020-05-13T09:55:06+00:00

Interrupt has been disabled in __schedule() with local_irq_disable() and enabled in finish_task_switch->finish_lock_switch() with local_irq_enabled(), So needn't to disable irq here. Signed-off-by: Liu Yibin Signed-off-by: Guo Ren

csky: Fixup calltrace panic

2020-05-13T09:55:06+00:00

The implementation of show_stack will panic with wrong fp: addr = *fp++; because the fp isn't checked properly. The current implementations of show_stack, wchan and stack_trace haven't been designed properly, so just deprecate them. This patch is a reference to riscv's way, all codes are modified from arm's. The patch is passed with: - cat /proc//stack - cat /proc//wchan - echo c > /proc/sysrq-trigger Signed-off-by: Guo Ren

csky: Fixup perf callchain unwind

2020-05-13T09:55:05+00:00

[ 5221.974084] Unable to handle kernel paging request at virtual address 0xfffff000, pc: 0x8002c18e [ 5221.985929] Oops: 00000000 [ 5221.989488] [ 5221.989488] CURRENT PROCESS: [ 5221.989488] [ 5221.992877] COMM=callchain_test PID=11962 [ 5221.995213] TEXT=00008000-000087e0 DATA=00009f1c-0000a018 BSS=0000a018-0000b000 [ 5221.999037] USER-STACK=7fc18e20 KERNEL-STACK=be204680 [ 5221.999037] [ 5222.003292] PC: 0x8002c18e (perf_callchain_kernel+0x3e/0xd4) [ 5222.007957] LR: 0x8002c198 (perf_callchain_kernel+0x48/0xd4) [ 5222.074873] Call Trace: [ 5222.074873] [<800a248e>] get_perf_callchain+0x20a/0x29c [ 5222.074873] [<8009d964>] perf_callchain+0x64/0x80 [ 5222.074873] [<8009dc1c>] perf_prepare_sample+0x29c/0x4b8 [ 5222.074873] [<8009de6e>] perf_event_output_forward+0x36/0x98 [ 5222.074873] [<800497e0>] search_exception_tables+0x20/0x44 [ 5222.074873] [<8002cbb6>] do_page_fault+0x92/0x378 [ 5222.074873] [<80098608>] __perf_event_overflow+0x54/0xdc [ 5222.074873] [<80098778>] perf_swevent_hrtimer+0xe8/0x164 [ 5222.074873] [<8002ddd0>] update_mmu_cache+0x0/0xd8 [ 5222.074873] [<8002c014>] user_backtrace+0x58/0xc4 [ 5222.074873] [<8002c0b4>] perf_callchain_user+0x34/0xd0 [ 5222.074873] [<800a2442>] get_perf_callchain+0x1be/0x29c [ 5222.074873] [<8009d964>] perf_callchain+0x64/0x80 [ 5222.074873] [<8009d834>] perf_output_sample+0x78c/0x858 [ 5222.074873] [<8009dc1c>] perf_prepare_sample+0x29c/0x4b8 [ 5222.074873] [<8009de94>] perf_event_output_forward+0x5c/0x98 [ 5222.097846] [ 5222.097846] [<800a0300>] perf_event_exit_task+0x58/0x43c [ 5222.097846] [<8006c874>] hrtimer_interrupt+0x104/0x2ec [ 5222.097846] [<800a0300>] perf_event_exit_task+0x58/0x43c [ 5222.097846] [<80437bb6>] dw_apb_clockevent_irq+0x2a/0x4c [ 5222.097846] [<8006c770>] hrtimer_interrupt+0x0/0x2ec [ 5222.097846] [<8005f2e4>] __handle_irq_event_percpu+0xac/0x19c [ 5222.097846] [<80437bb6>] dw_apb_clockevent_irq+0x2a/0x4c [ 5222.097846] [<8005f408>] handle_irq_event_percpu+0x34/0x88 [ 5222.097846] [<8005f480>] handle_irq_event+0x24/0x64 [ 5222.097846] [<8006218c>] handle_level_irq+0x68/0xdc [ 5222.097846] [<8005ec76>] __handle_domain_irq+0x56/0xa8 [ 5222.097846] [<80450e90>] ck_irq_handler+0xac/0xe4 [ 5222.097846] [<80029012>] csky_do_IRQ+0x12/0x24 [ 5222.097846] [<8002a3a0>] csky_irq+0x70/0x80 [ 5222.097846] [<800ca612>] alloc_set_pte+0xd2/0x238 [ 5222.097846] [<8002ddd0>] update_mmu_cache+0x0/0xd8 [ 5222.097846] [<800a0340>] perf_event_exit_task+0x98/0x43c The original fp check doesn't base on the real kernal stack region. Invalid fp address may cause kernel panic. Signed-off-by: Mao Han Signed-off-by: Guo Ren