Symbols are needed for tools to describe instruction addresses. Pages
allocated for ftrace's purposes need symbols to be created for them.
Add such symbols to be visible via /proc/kallsyms.
Example on x86 with CONFIG_DYNAMIC_FTRACE=y
# echo function > /sys/kernel/debug/tracing/current_tracer
# cat /proc/kallsyms | grep '\[__builtin__ftrace\]'
ffffffffc0238000 t ftrace_trampoline [__builtin__ftrace]
Note: This patch adds "__builtin__ftrace" as a module name in /proc/kallsyms for
symbols for pages allocated for ftrace's purposes, even though "__builtin__ftrace"
is not a module.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200512121922.8997-7-adrian.hunter@intel.com
Pull sysctl fixes from Al Viro:
"Fixups to regressions in sysctl series"
* 'work.sysctl' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
sysctl: reject gigantic reads/write to sysctl files
cdrom: fix an incorrect __user annotation on cdrom_sysctl_info
trace: fix an incorrect __user annotation on stack_trace_sysctl
random: fix an incorrect __user annotation on proc_do_entropy
net/sysctl: remove leftover __user annotations on neigh_proc_dointvec*
net/sysctl: use cpumask_parse in flow_limit_cpu_sysctl
No user pointers for sysctls anymore.
Fixes: 32927393dc ("sysctl: pass kernel pointers to ->proc_handler")
Reported-by: build test robot <lkp@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Move the bpf verifier trace check into the new switch statement in
HEAD.
Resolve the overlapping changes in hinic, where bug fixes overlap
the addition of VF support.
Signed-off-by: David S. Miller <davem@davemloft.net>
Booting one of my machines, it triggered the following crash:
Kernel/User page tables isolation: enabled
ftrace: allocating 36577 entries in 143 pages
Starting tracer 'function'
BUG: unable to handle page fault for address: ffffffffa000005c
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
PGD 2014067 P4D 2014067 PUD 2015063 PMD 7b253067 PTE 7b252061
Oops: 0003 [#1] PREEMPT SMP PTI
CPU: 0 PID: 0 Comm: swapper Not tainted 5.4.0-test+ #24
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
RIP: 0010:text_poke_early+0x4a/0x58
Code: 34 24 48 89 54 24 08 e8 bf 72 0b 00 48 8b 34 24 48 8b 4c 24 08 84 c0 74 0b 48 89 df f3 a4 48 83 c4 10 5b c3 9c 58 fa 48 89 df <f3> a4 50 9d 48 83 c4 10 5b e9 d6 f9 ff ff
0 41 57 49
RSP: 0000:ffffffff82003d38 EFLAGS: 00010046
RAX: 0000000000000046 RBX: ffffffffa000005c RCX: 0000000000000005
RDX: 0000000000000005 RSI: ffffffff825b9a90 RDI: ffffffffa000005c
RBP: ffffffffa000005c R08: 0000000000000000 R09: ffffffff8206e6e0
R10: ffff88807b01f4c0 R11: ffffffff8176c106 R12: ffffffff8206e6e0
R13: ffffffff824f2440 R14: 0000000000000000 R15: ffffffff8206eac0
FS: 0000000000000000(0000) GS:ffff88807d400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffa000005c CR3: 0000000002012000 CR4: 00000000000006b0
Call Trace:
text_poke_bp+0x27/0x64
? mutex_lock+0x36/0x5d
arch_ftrace_update_trampoline+0x287/0x2d5
? ftrace_replace_code+0x14b/0x160
? ftrace_update_ftrace_func+0x65/0x6c
__register_ftrace_function+0x6d/0x81
ftrace_startup+0x23/0xc1
register_ftrace_function+0x20/0x37
func_set_flag+0x59/0x77
__set_tracer_option.isra.19+0x20/0x3e
trace_set_options+0xd6/0x13e
apply_trace_boot_options+0x44/0x6d
register_tracer+0x19e/0x1ac
early_trace_init+0x21b/0x2c9
start_kernel+0x241/0x518
? load_ucode_intel_bsp+0x21/0x52
secondary_startup_64+0xa4/0xb0
I was able to trigger it on other machines, when I added to the kernel
command line of both "ftrace=function" and "trace_options=func_stack_trace".
The cause is the "ftrace=function" would register the function tracer
and create a trampoline, and it will set it as executable and
read-only. Then the "trace_options=func_stack_trace" would then update
the same trampoline to include the stack tracer version of the function
tracer. But since the trampoline already exists, it updates it with
text_poke_bp(). The problem is that text_poke_bp() called while
system_state == SYSTEM_BOOTING, it will simply do a memcpy() and not
the page mapping, as it would think that the text is still read-write.
But in this case it is not, and we take a fault and crash.
Instead, lets keep the ftrace trampolines read-write during boot up,
and then when the kernel executable text is set to read-only, the
ftrace trampolines get set to read-only as well.
Link: https://lkml.kernel.org/r/20200430202147.4dc6e2de@oasis.local.home
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: stable@vger.kernel.org
Fixes: 768ae4406a ("x86/ftrace: Use text_poke()")
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from userspace in common code. This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.
As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull tracing fixes from Steven Rostedt:
- Remove code I accidentally applied when doing a minor fix up to a
patch, and then using "git commit -a --amend", which pulled in some
other changes I was playing with.
- Remove an used variable in trace_events_inject code
- Fix function graph tracer when it traces a ftrace direct function.
It will now ignore tracing a function that has a ftrace direct
tramploine attached. This is needed for eBPF to use the ftrace direct
code.
* tag 'trace-v5.5-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace: Fix function_graph tracer interaction with BPF trampoline
tracing: remove set but not used variable 'buffer'
module: Remove accidental change of module_enable_x()
Depending on type of BPF programs served by BPF trampoline it can call original
function. In such case the trampoline will skip one stack frame while
returning. That will confuse function_graph tracer and will cause crashes with
bad RIP. Teach graph tracer to skip functions that have BPF trampoline attached.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull tracing updates from Steven Rostedt:
"New tracing features:
- New PERMANENT flag to ftrace_ops when attaching a callback to a
function.
As /proc/sys/kernel/ftrace_enabled when set to zero will disable
all attached callbacks in ftrace, this has a detrimental impact on
live kernel tracing, as it disables all that it patched. If a
ftrace_ops is registered to ftrace with the PERMANENT flag set, it
will prevent ftrace_enabled from being disabled, and if
ftrace_enabled is already disabled, it will prevent a ftrace_ops
with PREMANENT flag set from being registered.
- New register_ftrace_direct().
As eBPF would like to register its own trampolines to be called by
the ftrace nop locations directly, without going through the ftrace
trampoline, this function has been added. This allows for eBPF
trampolines to live along side of ftrace, perf, kprobe and live
patching. It also utilizes the ftrace enabled_functions file that
keeps track of functions that have been modified in the kernel, to
allow for security auditing.
- Allow for kernel internal use of ftrace instances.
Subsystems in the kernel can now create and destroy their own
tracing instances which allows them to have their own tracing
buffer, and be able to record events without worrying about other
users from writing over their data.
- New seq_buf_hex_dump() that lets users use the hex_dump() in their
seq_buf usage.
- Notifications now added to tracing_max_latency to allow user space
to know when a new max latency is hit by one of the latency
tracers.
- Wider spread use of generic compare operations for use of bsearch
and friends.
- More synthetic event fields may be defined (32 up from 16)
- Use of xarray for architectures with sparse system calls, for the
system call trace events.
This along with small clean ups and fixes"
* tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (51 commits)
tracing: Enable syscall optimization for MIPS
tracing: Use xarray for syscall trace events
tracing: Sample module to demonstrate kernel access to Ftrace instances.
tracing: Adding new functions for kernel access to Ftrace instances
tracing: Fix Kconfig indentation
ring-buffer: Fix typos in function ring_buffer_producer
ftrace: Use BIT() macro
ftrace: Return ENOTSUPP when DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not configured
ftrace: Rename ftrace_graph_stub to ftrace_stub_graph
ftrace: Add a helper function to modify_ftrace_direct() to allow arch optimization
ftrace: Add helper find_direct_entry() to consolidate code
ftrace: Add another check for match in register_ftrace_direct()
ftrace: Fix accounting bug with direct->count in register_ftrace_direct()
ftrace/selftests: Fix spelling mistake "wakeing" -> "waking"
tracing: Increase SYNTH_FIELDS_MAX for synthetic_events
ftrace/samples: Add a sample module that implements modify_ftrace_direct()
ftrace: Add modify_ftrace_direct()
tracing: Add missing "inline" in stub function of latency_fsnotify()
tracing: Remove stray tab in TRACE_EVAL_MAP_FILE's help text
tracing: Use seq_buf_hex_dump() to dump buffers
...
If a direct ftrace callback is at a location that does not have any other
ftrace helpers attached to it, it is possible to simply just change the
text to call the new caller (if the architecture supports it). But this
requires special architecture code. Currently, modify_ftrace_direct() uses a
trick to add a stub ftrace callback to the location forcing it to call the
ftrace iterator. Then it can change the direct helper to call the new
function in C, and then remove the stub. Removing the stub will have the
location now call the new location that the direct helper is using.
The new helper function does the registering the stub trick, but is a weak
function, allowing an architecture to override it to do something a bit more
direct.
Link: https://lore.kernel.org/r/20191115215125.mbqv7taqnx376yed@ast-mbp.dhcp.thefacebook.com
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
As testing for direct calls from the function graph tracer adds a little
overhead (which is a lot when tracing every function), add a counter that
can be used to test if function_graph tracer needs to test for a direct
caller or not.
It would have been nicer if we could use a static branch, but the static
branch logic fails when used within the function graph tracer trampoline.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Enable x86 to allow for register_ftrace_direct(), where a custom trampoline
may be called directly from an ftrace mcount/fentry location.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
As function_graph tracer modifies the return address to insert a trampoline
to trace the return of a function, it must be aware of a direct caller, as
when it gets called, the function's return address may not be at on the
stack where it expects. It may have to see if that return address points to
the a direct caller and adjust if it is.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add the start of the functionality to allow other trampolines to use the
ftrace mcount/fentry/nop location. This adds two new functions:
register_ftrace_direct() and unregister_ftrace_direct()
Both take two parameters: the first is the instruction address of where the
mcount/fentry/nop exists, and the second is the trampoline to have that
location called.
This will handle cases where ftrace is already used on that same location,
and will make it still work, where the registered direct called trampoline
will get called after all the registered ftrace callers are handled.
Currently, it will not allow for IP_MODIFY functions to be called at the
same locations, which include some kprobes and live kernel patching.
At this point, no architecture supports this. This is only the start of
implementing the framework.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
When using patchable-function-entry, the compiler will record the
callsites into a section named "__patchable_function_entries" rather
than "__mcount_loc". Let's abstract this difference behind a new
FTRACE_CALLSITE_SECTION, so that architectures don't have to handle this
explicitly (e.g. with custom module linker scripts).
As parisc currently handles this explicitly, it is fixed up accordingly,
with its custom linker script removed. Since FTRACE_CALLSITE_SECTION is
only defined when DYNAMIC_FTRACE is selected, the parisc module loading
code is updated to only use the definition in that case. When
DYNAMIC_FTRACE is not selected, modules shouldn't have this section, so
this removes some redundant work in that case.
To make sure that this is keep up-to-date for modules and the main
kernel, a comment is added to vmlinux.lds.h, with the existing ifdeffery
simplified for legibility.
I built parisc generic-{32,64}bit_defconfig with DYNAMIC_FTRACE enabled,
and verified that the section made it into the .ko files for modules.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Helge Deller <deller@gmx.de>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Torsten Duwe <duwe@suse.de>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Sven Schnelle <svens@stackframe.org>
Tested-by: Torsten Duwe <duwe@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: linux-parisc@vger.kernel.org
Architectures may need to perform special initialization of ftrace
callsites, and today they do so by special-casing ftrace_make_nop() when
the expected branch address is MCOUNT_ADDR. In some cases (e.g. for
patchable-function-entry), we don't have an mcount-like symbol and don't
want a synthetic MCOUNT_ADDR, but we may need to perform some
initialization of callsites.
To make it possible to separate initialization from runtime
modification, and to handle cases without an mcount-like symbol, this
patch adds an optional ftrace_init_nop() function that architectures can
implement, which does not pass a branch address.
Where an architecture does not provide ftrace_init_nop(), we will fall
back to the existing behaviour of calling ftrace_make_nop() with
MCOUNT_ADDR.
At the same time, ftrace_code_disable() is renamed to
ftrace_nop_initialize() to make it clearer that it is intended to
intialize a callsite into a disabled state, and is not for disabling a
callsite that has been runtime enabled. The kerneldoc description of rec
arguments is updated to cover non-mcount callsites.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Torsten Duwe <duwe@suse.de>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Sven Schnelle <svens@stackframe.org>
Tested-by: Torsten Duwe <duwe@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>
Livepatch uses ftrace for redirection to new patched functions. It means
that if ftrace is disabled, all live patched functions are disabled as
well. Toggling global 'ftrace_enabled' sysctl thus affect it directly.
It is not a problem per se, because only administrator can set sysctl
values, but it still may be surprising.
Introduce PERMANENT ftrace_ops flag to amend this. If the
FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be
disabled by disabling ftrace_enabled. Equally, a callback with the flag
set cannot be registered if ftrace_enabled is disabled.
Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull tracing updates from Steven Rostedt:
"The major changes in this tracing update includes:
- Removal of non-DYNAMIC_FTRACE from 32bit x86
- Removal of mcount support from x86
- Emulating a call from int3 on x86_64, fixes live kernel patching
- Consolidated Tracing Error logs file
Minor updates:
- Removal of klp_check_compiler_support()
- kdb ftrace dumping output changes
- Accessing and creating ftrace instances from inside the kernel
- Clean up of #define if macro
- Introduction of TRACE_EVENT_NOP() to disable trace events based on
config options
And other minor fixes and clean ups"
* tag 'trace-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits)
x86: Hide the int3_emulate_call/jmp functions from UML
livepatch: Remove klp_check_compiler_support()
ftrace/x86: Remove mcount support
ftrace/x86_32: Remove support for non DYNAMIC_FTRACE
tracing: Simplify "if" macro code
tracing: Fix documentation about disabling options using trace_options
tracing: Replace kzalloc with kcalloc
tracing: Fix partial reading of trace event's id file
tracing: Allow RCU to run between postponed startup tests
tracing: Fix white space issues in parse_pred() function
tracing: Eliminate const char[] auto variables
ring-buffer: Fix mispelling of Calculate
tracing: probeevent: Fix to make the type of $comm string
tracing: probeevent: Do not accumulate on ret variable
tracing: uprobes: Re-enable $comm support for uprobe events
ftrace/x86_64: Emulate call function while updating in breakpoint handler
x86_64: Allow breakpoints to emulate call instructions
x86_64: Add gap to int3 to allow for call emulation
tracing: kdb: Allow ftdump to skip all but the last few entries
tracing: Add trace_total_entries() / trace_total_entries_cpu()
...
Pull tracing updates from Steven Rostedt:
- Rework of the kprobe/uprobe and synthetic events to consolidate all
the dynamic event code. This will make changes in the future easier.
- Partial rewrite of the function graph tracing infrastructure. This
will allow for multiple users of hooking onto functions to get the
callback (return) of the function. This is the ground work for having
kprobes and function graph tracer using one code base.
- Clean up of the histogram code that will facilitate adding more
features to the histograms in the future.
- Addition of str_has_prefix() and a few use cases. There currently is
a similar function strstart() that is used in a few places, but only
returns a bool and not a length. These instances will be removed in
the future to use str_has_prefix() instead.
- A few other various clean ups as well.
* tag 'trace-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (57 commits)
tracing: Use the return of str_has_prefix() to remove open coded numbers
tracing: Have the historgram use the result of str_has_prefix() for len of prefix
tracing: Use str_has_prefix() instead of using fixed sizes
tracing: Use str_has_prefix() helper for histogram code
string.h: Add str_has_prefix() helper function
tracing: Make function ‘ftrace_exports’ static
tracing: Simplify printf'ing in seq_print_sym
tracing: Avoid -Wformat-nonliteral warning
tracing: Merge seq_print_sym_short() and seq_print_sym_offset()
tracing: Add hist trigger comments for variable-related fields
tracing: Remove hist trigger synth_var_refs
tracing: Use hist trigger's var_ref array to destroy var_refs
tracing: Remove open-coding of hist trigger var_ref management
tracing: Use var_refs[] for hist trigger reference checking
tracing: Change strlen to sizeof for hist trigger static strings
tracing: Remove unnecessary hist trigger struct field
tracing: Fix ftrace_graph_get_ret_stack() to use task and not current
seq_buf: Use size_t for len in seq_buf_puts()
seq_buf: Make seq_buf_puts() null-terminate the buffer
arm64: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack
...
