kernel.git/arch/s390/kernel/traps.c, branch linux-5.13.y

s390/traps: do not test MONITOR CALL without CONFIG_BUG

2021-07-25T12:37:31Z

[ Upstream commit b8e9cc20b808e26329090c19ff80b7f5098e98ff ] tinyconfig fails to boot, because without CONFIG_BUG report_bug() always returns BUG_TRAP_TYPE_BUG, which causes mc 0,0 in test_monitor_call() to panic. Fix by skipping the test without CONFIG_BUG. Signed-off-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/entry: add support for syscall stack randomization

2021-04-30T15:20:39Z

This adds support for adding a random offset to the stack while handling syscalls. The patch uses get_tod_clock_fast() as this is considered good enough and has much less performance penalty compared to using get_random_int(). The patch also adds randomization in pgm_check_handler() as the sigreturn/rt_sigreturn system calls might be called from there. Signed-off-by: Sven Schnelle Link: https://lore.kernel.org/r/20210429091451.1062594-1-svens@linux.ibm.com Signed-off-by: Heiko Carstens

s390/traps,mm: add conditional trap handlers

2021-04-12T10:46:42Z

Add conditional trap handlers similar to conditional system calls (COND_SYSCALL), to reduce the number of ifdefs. Trap handlers which may or may not exist depending on config options are supposed to have a COND_TRAP entry, which redirects to default_trap_handler() for non-existent trap handlers during link time. This allows to get rid of the secure execution trap handlers for the !PGSTE case. Reviewed-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390/traps: convert pgm_check.S to C

2021-04-12T10:46:41Z

Convert the program check table to C. Which allows to get rid of yet another assembler file, and also enables proper type checking for the table. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens

s390: convert to generic entry

2021-01-19T11:29:26Z

This patch converts s390 to use the generic entry infrastructure from kernel/entry/*. There are a few special things on s390: - PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't know about our PIF flags in exit_to_user_mode_loop(). - The old code had several ways to restart syscalls: a) PIF_SYSCALL_RESTART, which was only set during execve to force a restart after upgrading a process (usually qemu-kvm) to pgste page table extensions. b) PIF_SYSCALL, which is set by do_signal() to indicate that the current syscall should be restarted. This is changed so that do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use PIF_SYSCALL doesn't work with the generic code, and changing it to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART more unique. - On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by executing a svc instruction on the process stack which causes a fault. While handling that fault the fault code sets PIF_SYSCALL to hand over processing to the syscall code on exit to usermode. The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets a return value for a syscall. The s390x ptrace ABI uses r2 both for the syscall number and return value, so ptrace cannot set the syscall number + return value at the same time. The flag makes handling that a bit easier. do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET is set. CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY. CR1/7/13 will be checked both on kernel entry and exit to contain the correct asces. Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik

s390/kernel: expand exception table logic to allow new handling options

2020-07-20T08:55:50Z

This is a s390 port of commit 548acf19234d ("x86/mm: Expand the exception table logic to allow new handling options"), which is needed for implementing BPF_PROBE_MEM on s390. The new handler field is made 64-bit in order to allow pointing from dynamically allocated entries to handlers in kernel text. Unlike on x86, NULL is used instead of ex_handler_default. This is because exception tables are used by boot/text_dma.S, and it would be a pain to preserve ex_handler_default. The new infrastructure is ignored in early_pgm_check_handler, since there is no pt_regs. Signed-off-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens

s390/traps: mark test_monitor_call __init

2020-03-11T13:18:44Z

Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: fix __EMIT_BUG() macro

2020-01-22T12:05:35Z

Setting a kprobe on getname_flags() failed: $ echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events -bash: echo: write error: Invalid argument Debugging the kprobes code showed that the address of getname_flags() is contained in the __bug_table. Kprobes doesn't allow to set probes at BUG() locations. $ objdump -j __bug_table -x build/fs/namei.o [..] 0000000000000108 R_390_PC32 .text+0x00000000000075a8 000000000000010c R_390_PC32 .L223+0x0000000000000004 I was expecting getname_flags() to start with a BUG(), but: 7598: e3 20 10 00 00 04 lg %r2,0(%r1) 759e: c0 f4 00 00 00 00 jg 759e 75a0: R_390_PLT32DBL kmem_cache_free+0x2 75a4: a7 f4 00 01 j 75a6 00000000000075a8 : 75a8: c0 04 00 00 00 00 brcl 0,75a8 75ae: eb 6f f0 48 00 24 stmg %r6,%r15,72(%r15) 75b4: b9 04 00 ef lgr %r14,%r15 75b8: e3 f0 ff a8 ff 71 lay %r15,-88(%r15) So the BUG() is actually the last opcode of the previous function. Fix this by switching to using the MONITOR CALL (MC) instruction, and set the entry in __bug_table to the beginning of that MC. Reviewed-by: Heiko Carstens Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik

Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2019-07-09T04:48:15Z

Pull force_sig() argument change from Eric Biederman: "A source of error over the years has been that force_sig has taken a task parameter when it is only safe to use force_sig with the current task. The force_sig function is built for delivering synchronous signals such as SIGSEGV where the userspace application caused a synchronous fault (such as a page fault) and the kernel responded with a signal. Because the name force_sig does not make this clear, and because the force_sig takes a task parameter the function force_sig has been abused for sending other kinds of signals over the years. Slowly those have been fixed when the oopses have been tracked down. This set of changes fixes the remaining abusers of force_sig and carefully rips out the task parameter from force_sig and friends making this kind of error almost impossible in the future" * 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits) signal/x86: Move tsk inside of CONFIG_MEMORY_FAILURE in do_sigbus signal: Remove the signal number and task parameters from force_sig_info signal: Factor force_sig_info_to_task out of force_sig_info signal: Generate the siginfo in force_sig signal: Move the computation of force into send_signal and correct it. signal: Properly set TRACE_SIGNAL_LOSE_INFO in __send_signal signal: Remove the task parameter from force_sig_fault signal: Use force_sig_fault_to_task for the two calls that don't deliver to current signal: Explicitly call force_sig_fault on current signal/unicore32: Remove tsk parameter from __do_user_fault signal/arm: Remove tsk parameter from __do_user_fault signal/arm: Remove tsk parameter from ptrace_break signal/nds32: Remove tsk parameter from send_sigtrap signal/riscv: Remove tsk parameter from do_trap signal/sh: Remove tsk parameter from force_sig_info_fault signal/um: Remove task parameter from send_sigtrap signal/x86: Remove task parameter from send_sigtrap signal: Remove task parameter from force_sig_mceerr signal: Remove task parameter from force_sig signal: Remove task parameter from force_sigsegv ...

s390/traps: simplify data exception handler

2019-06-15T10:25:45Z

Simplify conditions and remove unnecessary variable in data exception handler. Signed-off-by: Vasily Gorbik Reviewed-by: Heiko Carstens Reviewed-by: Hendrik Brueckner Signed-off-by: Heiko Carstens