- 22 Oct, 2021 6 commits
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Masami Hiramatsu authored
Currently kretprobe on ARM just fills r0-r11 of pt_regs, but that is not enough for the stacktrace. Moreover, from the user kretprobe handler, stacktrace needs a frame pointer on the __kretprobe_trampoline. This adds a frame pointer on __kretprobe_trampoline for both gcc and clang case. Those have different frame pointer so we need different but similar stack on pt_regs. Gcc makes the frame pointer (fp) to point the 'pc' address of the {fp, ip (=sp), lr, pc}, this means {r11, r13, r14, r15}. Thus if we save the r11 (fp) on pt_regs->r12, we can make this set on the end of pt_regs. On the other hand, Clang makes the frame pointer to point the 'fp' address of {fp, lr} on stack. Since the next to the pt_regs->lr is pt_regs->sp, I reused the pair of pt_regs->fp and pt_regs->ip. So this stores the 'lr' on pt_regs->ip and make the fp to point pt_regs->fp. For both cases, saves __kretprobe_trampoline address to pt_regs->lr, so that the stack tracer can identify this frame pointer has been made by the __kretprobe_trampoline. Note that if the CONFIG_FRAME_POINTER is not set, this keeps fp as is. Signed-off-by:Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by:
Nick Desaulniers <ndesaulniers@google.com> Signed-off-by:
Steven Rostedt (VMware) <rostedt@goodmis.org>
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Masami Hiramatsu authored
Currently the stacktrace on clang compiled arm kernel uses the 'lr' register to find the first frame address from pt_regs. However, that is wrong after calling another function, because the 'lr' register is used by 'bl' instruction and never be recovered. As same as gcc arm kernel, directly use the frame pointer (r11) of the pt_regs to find the first frame address. Note that this fixes kretprobe stacktrace issue only with CONFIG_UNWINDER_FRAME_POINTER=y. For the CONFIG_UNWINDER_ARM, we need another fix. Signed-off-by:
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Masami Hiramatsu authored
Since the kretprobe replaces the function return address with the kretprobe_trampoline on the stack, stack unwinder shows it instead of the correct return address. This checks whether the next return address is the __kretprobe_trampoline(), and if so, try to find the correct return address from the kretprobe instance list. For this purpose this adds 'kr_cur' loop cursor to memorize the current kretprobe instance. With this fix, now arm64 can enable CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE, and pass the kprobe self tests. Signed-off-by:
Will Deacon <will@kernel.org> Signed-off-by:
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Masami Hiramatsu authored
Make a frame pointer (make the x29 register points the address of pt_regs->regs[29]) on __kretprobe_trampoline. This frame pointer will be used by the stacktracer when it is called from the kretprobe handlers. In this case, the stack tracer will unwind stack to trampoline_probe_handler() and find the next frame pointer in the stack frame of the __kretprobe_trampoline(). Signed-off-by:
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Masami Hiramatsu authored
Record the frame pointer instead of stack address with kretprobe instance as the identifier on the instance list. Since arm64 always enable CONFIG_FRAME_POINTER, we can use the actual frame pointer (x29). This will allow the stacktrace code to find the original return address from the FP alone. Signed-off-by:
Mark Rutland <mark.rutland@arm.com> Signed-off-by:
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Masami Hiramatsu authored
Compile kretprobe related stacktrace entry recovery code and unwind_state::kr_cur field only when CONFIG_KRETPROBES=y. Signed-off-by:
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- 21 Oct, 2021 12 commits
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Sven Schnelle authored
This converts the kprobes testcases to use the kunit framework. It adds a dependency on CONFIG_KUNIT, and the output will change to TAP: TAP version 14 1..1 # Subtest: kprobes_test 1..4 random: crng init done ok 1 - test_kprobe ok 2 - test_kprobes ok 3 - test_kretprobe ok 4 - test_kretprobes ok 1 - kprobes_test Note that the kprobes testcases are no longer run immediately after kprobes initialization, but as a late initcall when kunit is initialized. kprobes itself is initialized with an early initcall, so the order is still correct. Signed-off-by:Sven Schnelle <svens@linux.ibm.com> Acked-by:
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Arnd Bergmann authored
clang started warning about excessive stack usage in hist_trigger_print_key() kernel/trace/trace_events_hist.c:4723:13: error: stack frame size (1336) exceeds limit (1024) in function 'hist_trigger_print_key' [-Werror,-Wframe-larger-than] The problem is that there are two 512-byte arrays on the stack if hist_trigger_stacktrace_print() gets inlined. I don't think this has changed in the past five years, but something probably changed the inlining decisions made by the compiler, so the problem is now made more obvious. Rather than printing the symbol names into separate buffers, it seems we can simply use the special %ps format string modifier to print the pointers symbolically and get rid of both buffers. Marking hist_trigger_stacktrace_print() would be a simpler way of avoiding the warning, but that would not address the excessive stack usage. Link: https://lkml.kernel.org/r/20211019153337.294790-1-arnd@kernel.org Fixes: 69a0200c ("tracing: Add hist trigger support for stacktraces as keys") Link: https://lore.kernel.org/all/20211015095704.49a99859@gandalf.local.home/Reviewed-by:
Tom Zanussi <zanussi@kernel.org> Tested-by:
Arnd Bergmann <arnd@arndb.de> Signed-off-by:
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Steven Rostedt (VMware) authored
The current text of the explanation of the transition bit in the trace recursion protection is not very clear. Improve the text, so that when all the archs no longer have the issue of tracing between a start of a new (interrupt) context and updating the preempt_count to reflect the new context, that it may be removed. Link: https://lore.kernel.org/all/20211018220203.064a42ed@gandalf.local.home/Suggested-by:
Petr Mladek <pmladek@suse.com> Signed-off-by:
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Steven Rostedt (VMware) authored
Currently to switch a set of "multi" direct trampolines from one trampoline to another, a full shutdown of the current set needs to be done, followed by an update to what trampoline the direct callers would call, and then re-enabling the callers. This leaves a time when the functions will not be calling anything, and events may be missed. Instead, use a trick to allow all the functions with direct trampolines attached will always call either the new or old trampoline while the switch is happening. To do this, first attach a "dummy" callback via ftrace to all the functions that the current direct trampoline is attached to. This will cause the functions to call the "list func" instead of the direct trampoline. The list function will call the direct trampoline "helper" that will set the function it should call as it returns back to the ftrace trampoline. At this moment, the direct caller descriptor can safely update the direct call trampoline. The list function will pick either the new or old function (depending on the memory coherency model of the architecture). Now removing the dummy function from each of the locations of the direct trampoline caller, will put back the direct call, but now to the new trampoline. A better visual is: [ Changing direct call from my_direct_1 to my_direct_2 ] <traced_func>: call my_direct_1 |||||||||||||||||||| vvvvvvvvvvvvvvvvvvvv <traced_func>: call ftrace_caller <ftrace_caller>: [..] call ftrace_ops_list_func ftrace_ops_list_func() { ops->func() -> direct_helper -> set rax to my_direct_1 or my_direct_2 } call rax (to either my_direct_1 or my_direct_2 |||||||||||||||||||| vvvvvvvvvvvvvvvvvvvv <traced_func>: call my_direct_2 Link: https://lore.kernel.org/all/20211014162819.5c85618b@gandalf.local.home/Acked-by:Jiri Olsa <jolsa@redhat.com> Signed-off-by:
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Jiri Olsa authored
Adding simple module that uses multi direct interface: register_ftrace_direct_multi unregister_ftrace_direct_multi The init function registers trampoline for 2 functions, and exit function unregisters them. Link: https://lkml.kernel.org/r/20211008091336.33616-9-jolsa@kernel.orgSigned-off-by:
Jiri Olsa <jolsa@kernel.org> Signed-off-by:
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Jiri Olsa authored
Adding interface to modify registered direct function for ftrace_ops. Adding following function: modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) The function changes the currently registered direct function for all attached functions. Link: https://lkml.kernel.org/r/20211008091336.33616-8-jolsa@kernel.orgSigned-off-by:
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Jiri Olsa authored
Adding interface to register multiple direct functions within single call. Adding following functions: register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) The register_ftrace_direct_multi registers direct function (addr) with all functions in ops filter. The ops filter can be updated before with ftrace_set_filter_ip calls. All requested functions must not have direct function currently registered, otherwise register_ftrace_direct_multi will fail. The unregister_ftrace_direct_multi unregisters ops related direct functions. Link: https://lkml.kernel.org/r/20211008091336.33616-7-jolsa@kernel.orgSigned-off-by:
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Jiri Olsa authored
Factor out the code that adds (ip, addr) tuple to direct_functions hash in new ftrace_add_rec_direct function. It will be used in following patches. Link: https://lkml.kernel.org/r/20211008091336.33616-6-jolsa@kernel.orgSigned-off-by:
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Steven Rostedt (VMware) authored
There's a new test in trace_selftest_startup_function_graph() that requires the use of ftrace args being supported as well does some tricks with dynamic tracing. Although this code checks HAVE_DYNAMIC_FTRACE_WITH_ARGS it fails to check DYNAMIC_FTRACE, and the kernel fails to build due to that dependency. Also only define the prototype of trace_direct_tramp() if it is used. Link: https://lkml.kernel.org/r/20211021134357.7f48e173@gandalf.local.homeAcked-by:
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Jiri Olsa authored
Adding selftest for checking that direct trampoline can co-exist together with graph tracer on same function. This is supported for CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS config option, which is defined only for x86_64 for now. Link: https://lkml.kernel.org/r/20211008091336.33616-5-jolsa@kernel.orgSigned-off-by:
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Steven Rostedt (VMware) authored
We don't need special hook for graph tracer entry point, but instead we can use graph_ops::func function to install the return_hooker. This moves the graph tracing setup _before_ the direct trampoline prepares the stack, so the return_hooker will be called when the direct trampoline is finished. This simplifies the code, because we don't need to take into account the direct trampoline setup when preparing the graph tracer hooker and we can allow function graph tracer on entries registered with direct trampoline. Link: https://lkml.kernel.org/r/20211008091336.33616-4-jolsa@kernel.org [fixed compile error reported by kernel test robot <lkp@intel.com>] Signed-off-by:
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Steven Rostedt (VMware) authored
The function graph tracer is going to now depend on ARCH_SUPPORTS_FTRACE_OPS, as that also means that it can support ftrace args. Since ARCH_SUPPORTS_FTRACE_OPS depends on DYNAMIC_FTRACE, this means that the function graph tracer for x86_64 will need to depend on DYNAMIC_FTRACE. Link: https://lkml.kernel.org/r/20211020233555.16b0dbf2@rorschach.local.homeSigned-off-by:
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- 20 Oct, 2021 6 commits
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Steven Rostedt (VMware) authored
Removing the fault protection code when writing return_hooker to stack. As Steven noted: > That protection was there from the beginning due to being "paranoid", > considering ftrace was bricking network cards. But that protection > would not have even protected against that. Link: https://lkml.kernel.org/r/20211008091336.33616-3-jolsa@kernel.orgSigned-off-by:
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Jiri Olsa authored
There's identical move 2 lines earlier. Link: https://lkml.kernel.org/r/20211008091336.33616-2-jolsa@kernel.orgSigned-off-by:
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Steven Rostedt (VMware) authored
Now that there are three different instances of doing the addition trick to the preempt_count() and NMI_MASK, HARDIRQ_MASK and SOFTIRQ_OFFSET macros, it deserves a helper function defined in the preempt.h header. Add the interrupt_context_level() helper and replace the three instances that do that logic with it. Link: https://lore.kernel.org/all/20211015142541.4badd8a9@gandalf.local.home/Signed-off-by:
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Steven Rostedt (VMware) authored
Instead of having branches that adds noise to the branch prediction, use the addition logic to set the bit for the level of interrupt context that the state is currently in. This copies the logic from perf's get_recursion_context() function. Link: https://lore.kernel.org/all/20211015161702.GF174703@worktop.programming.kicks-ass.net/Suggested-by:
Peter Zijlstra <peterz@infradead.org> Signed-off-by:
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Kalesh Singh authored
If CONFIG_CFI_CLANG=y, attempting to read an event histogram will cause the kernel to panic due to failed CFI check. 1. echo 'hist:keys=common_pid' >> events/sched/sched_switch/trigger 2. cat events/sched/sched_switch/hist 3. kernel panics on attempting to read hist This happens because the sort() function expects a generic int (*)(const void *, const void *) pointer for the compare function. To prevent this CFI failure, change tracing map cmp_entries_* function signatures to match this. Also, fix the build error reported by the kernel test robot [1]. [1] https://lore.kernel.org/r/202110141140.zzi4dRh4-lkp@intel.com/ Link: https://lkml.kernel.org/r/20211014045217.3265162-1-kaleshsingh@google.comSigned-off-by:Kalesh Singh <kaleshsingh@google.com> Reported-by:
kernel test robot <lkp@intel.com> Signed-off-by:
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Steven Rostedt (VMware) authored
In an effort to enable -Wcast-function-type in the top-level Makefile to support Control Flow Integrity builds, all function casts need to be removed. This means that ftrace_ops_list_func() can no longer be defined as ftrace_ops_no_ops(). The reason for ftrace_ops_no_ops() is to use that when an architecture calls ftrace_ops_list_func() with only two parameters (called from assembly). And to make sure there's no C side-effects, those archs call ftrace_ops_no_ops() which only has two parameters, as ftrace_ops_list_func() has four parameters. Instead of a typecast, use vmlinux.lds.h to define ftrace_ops_list_func() to arch_ftrace_ops_list_func() that will define the proper set of parameters. Link: https://lore.kernel.org/r/20200614070154.6039-1-oscar.carter@gmx.com Link: https://lkml.kernel.org/r/20200617165616.52241bde@oasis.local.home Link: https://lore.kernel.org/all/20211005053922.GA702049@embeddedor/Requested-by:
Oscar Carter <oscar.carter@gmx.com> Reported-by:
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- 13 Oct, 2021 1 commit
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Changbin Du authored
Replace the obsolete and ambiguos macro in_irq() with new macro in_hardirq(). Link: https://lkml.kernel.org/r/20210930000342.6016-1-changbin.du@gmail.comReviewed-by:
Changbin Du <changbin.du@gmail.com> Signed-off-by:
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- 11 Oct, 2021 10 commits
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Carles Pey authored
A self test is provided for the trace function removal functionality. Link: https://lkml.kernel.org/r/20210918153043.318016-2-carles.pey@gmail.comSigned-off-by:
Carles Pey <carles.pey@gmail.com> Signed-off-by:
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Masami Hiramatsu authored
Cleanup dummy headers in tools/bootconfig/include except for tools/bootconfig/include/linux/bootconfig.h. For this change, I use __KERNEL__ macro to split kernel header #include and introduce xbc_alloc_mem() and xbc_free_mem(). Link: https://lkml.kernel.org/r/163187299574.2366983.18371329724128746091.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Replace u16 and u32 with uint16_t and uint32_t so that the tools/bootconfig only needs <stdint.h>. Link: https://lkml.kernel.org/r/163187298835.2366983.9838262576854319669.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Print all error message in stderr. This also removes unneeded tools/bootconfig/include/linux/printk.h. Link: https://lkml.kernel.org/r/163187298106.2366983.15210300267326257397.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Remove unused xbc_debug_dump() from bootconfig for clean up the code. Link: https://lkml.kernel.org/r/163187297371.2366983.12943349701785875450.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Split bootconfig data parser to build tree code from xbc_init(). This is an internal cosmetic change. Link: https://lkml.kernel.org/r/163187296647.2366983.15590065167920474865.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Avoid using this noisy name and use more calm one. This is just a name change. No functional change. Link: https://lkml.kernel.org/r/163187295918.2366983.5231840238429996027.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Run the bootconfig test script when build all target so that user can notice any issue when build it. Link: https://lkml.kernel.org/r/163187295173.2366983.18295281097397499118.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Add xbc_get_info() API which allows user to get the number of used xbc_nodes and the size of bootconfig data. This is also useful for checking the bootconfig is initialized or not. Link: https://lkml.kernel.org/r/163177340877.682366.4360676589783197627.stgit@devnote2Signed-off-by:
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Masami Hiramatsu authored
Allocate 'xbc_data' in the xbc_init() so that it does not need to care about the ownership of the copied data. Link: https://lkml.kernel.org/r/163177339986.682366.898762699429769117.stgit@devnote2Suggested-by:
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- 08 Oct, 2021 3 commits
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Weizhao Ouyang authored
Most of ARCHs use empty ftrace_dyn_arch_init(), introduce a weak common ftrace_dyn_arch_init() to cleanup them. Link: https://lkml.kernel.org/r/20210909090216.1955240-1-o451686892@gmail.com Acked-by: Heiko Carstens <hca@linux.ibm.com> (s390) Acked-by: Helge Deller <deller@gmx.de> (parisc) Signed-off-by:
Weizhao Ouyang <o451686892@gmail.com> Signed-off-by:
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Steven Rostedt (VMware) authored
When building the files in the tracefs file system, do not by default set any permissions for OTH (other). This will make it easier for admins who want to define a group for accessing tracefs and not having to first disable all the permission bits for "other" in the file system. As tracing can leak sensitive information, it should never by default allowing all users access. An admin can still set the permission bits for others to have access, which may be useful for creating a honeypot and seeing who takes advantage of it and roots the machine. Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.orgSigned-off-by:
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Steven Rostedt (VMware) authored
The tracefs file system is by default mounted such that only root user can access it. But there are legitimate reasons to create a group and allow those added to the group to have access to tracing. By changing the permissions of the tracefs mount point to allow access, it will allow group access to the tracefs directory. There should not be any real reason to allow all access to the tracefs directory as it contains sensitive information. Have the default permission of directories being created not have any OTH (other) bits set, such that an admin that wants to give permission to a group has to first disable all OTH bits in the file system. Link: https://lkml.kernel.org/r/20210818153038.664127804@goodmis.orgSigned-off-by:
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- 07 Oct, 2021 1 commit
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Steven Rostedt (VMware) authored
The upper and lower variables are set as link lists to add into the sparse array. If they are NULL, after the needed allocations are done, then there is nothing to add. But they need to be initialized to NULL for this to work. Link: https://lore.kernel.org/all/221bc7ba-a475-1cb9-1bbe-730bb9c2d448@canonical.com/ Fixes: 8d6e9098 ("tracing: Create a sparse bitmask for pid filtering") Reported-by:
Colin Ian King <colin.king@canonical.com> Signed-off-by:
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- 05 Oct, 2021 1 commit
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Steven Rostedt (VMware) authored
When the trace_pid_list was created, the default pid max was 32768. Creating a bitmask that can hold one bit for all 32768 took up 4096 (one page). Having a one page bitmask was not much of a problem, and that was used for mapping pids. But today, systems are bigger and can run more tasks, and now the default pid_max is usually set to 4194304. Which means to handle that many pids requires 524288 bytes. Worse yet, the pid_max can be set to 2^30 (1073741824 or 1G) which would take 134217728 (128M) of memory to store this array. Since the pid_list array is very sparsely populated, it is a huge waste of memory to store all possible bits for each pid when most will not be set. Instead, use a page table scheme to store the array, and allow this to handle up to 30 bit pids. The pid_mask will start out with 256 entries for the first 8 MSB bits. This will cost 1K for 32 bit architectures and 2K for 64 bit. Each of these will have a 256 array to store the next 8 bits of the pid (another 1 or 2K). These will hold an 2K byte bitmask (which will cover the LSB 14 bits or 16384 pids). When the trace_pid_list is allocated, it will have the 1/2K upper bits allocated, and then it will allocate a cache for the next upper chunks and the lower chunks (default 6 of each). Then when a bit is "set", these chunks will be pulled from the free list and added to the array. If the free list gets down to a lever (default 2), it will trigger an irqwork that will refill the cache back up. On clearing a bit, if the clear causes the bitmask to be zero, that chunk will then be placed back into the free cache for later use, keeping the need to allocate more down to a minimum. Signed-off-by:
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