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Switch to the batched version of the jump label update functions so
instruction cache maintenance is deferred until the end of the update.
Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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If copy_to_kernel_nofault() failed, no need to flush icache and just
return immediately.
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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set_memory_rw() and set_memory_rox() may fail, so we should check the
return values and return immediately in larch_insn_text_copy().
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Fix the warning:
BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1
caller is larch_insn_text_copy+0x40/0xf0
Simply changing it to raw_smp_processor_id() is not enough: if preempt
and CPU hotplug happens after raw_smp_processor_id() but before calling
stop_machine(), the CPU where raw_smp_processor_id() has run may become
offline when stop_machine() and no CPU will run copy_to_kernel_nofault()
in text_copy_cb(). Thus guard the larch_insn_text_copy() calls with
cpus_read_lock() and change stop_machine() to stop_machine_cpuslocked()
to prevent this.
I've considered moving the locks inside larch_insn_text_copy() but
doing so seems not an easy hack. In bpf_arch_text_poke() obviously the
memcpy() call must be guarded by text_mutex, so we have to leave the
acquire of text_mutex out of larch_insn_text_copy(). But in the entire
kernel the acquire of mutexes is always after cpus_read_lock(), so we
cannot put cpus_read_lock() into larch_insn_text_copy() while leaving
the text_mutex acquire out (or we risk a deadlock due to inconsistent
lock acquire order). So let's fix the bug first and leave the posssible
refactor as future work.
Fixes: 9fbd18cf4c69 ("LoongArch: BPF: Add dynamic code modification support")
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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The atomic instructions sc.q, llacq.{w/d}, screl.{w/d} were newly added
in the LoongArch Reference Manual v1.10, it is necessary to handle them
in insns_not_supported() to avoid putting a breakpoint in the middle of
a ll/sc atomic sequence, otherwise it will loop forever for kprobes and
uprobes.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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This commit adds support for BPF dynamic code modification on the
LoongArch architecture:
1. Add bpf_arch_text_copy() for instruction block copying.
2. Add bpf_arch_text_poke() for runtime instruction patching.
3. Add bpf_arch_text_invalidate() for code invalidation.
On LoongArch, since symbol addresses in the direct mapping region can't
be reached via relative jump instructions from the paged mapping region,
we use the move_imm+jirl instruction pair as absolute jump instructions.
These require 2-5 instructions, so we reserve 5 NOP instructions in the
program as placeholders for function jumps.
The larch_insn_text_copy() function is solely used for BPF. And the use
of larch_insn_text_copy() requires PAGE_SIZE alignment. Currently, only
the size of the BPF trampoline is page-aligned.
Co-developed-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Add larch_insn_gen_beq() and larch_insn_gen_bne() helpers which will be
used in BPF trampoline implementation.
Reviewed-by: Hengqi Chen <hengqi.chen@gmail.com>
Co-developed-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
Co-developed-by: Youling Tang <tangyouling@kylinos.cn>
Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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The branch instructions beq, bne, blt, bge, bltu, bgeu and jirl belong
to the format reg2i16, but the sequence of oprand is different for the
instruction jirl. So adjust the parameter order of emit_jirl() to make
it more readable correspond with the Instruction Set Architecture manual.
Here are the instruction formats:
beq rj, rd, offs16
bne rj, rd, offs16
blt rj, rd, offs16
bge rj, rd, offs16
bltu rj, rd, offs16
bgeu rj, rd, offs16
jirl rd, rj, offs16
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#branch-instructions
Suggested-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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There exist various break insns such as BRK_KPROBE_BP, BRK_KPROBE_SSTEPBP,
BRK_UPROBE_BP and BRK_UPROBE_XOLBP, add larch_insn_gen_break() to generate
break insns simpler, this is preparation for later patch.
Tested-by: Jeff Xie <xiehuan09@gmail.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Like llsc instructions, the atomic memory access instructions shouldn't
be supported for probing, so check for them in insns_not_supported().
Closes: https://lore.kernel.org/all/SY4P282MB351877A70A0333C790FE85A5C09C9@SY4P282MB3518.AUSP282.PROD.OUTLOOK.COM/
Tested-by: Jeff Xie <xiehuan09@gmail.com>
Reported-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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The three functions insns_not_supported(), insns_need_simulation() and
arch_simulate_insn() will be used for uprobes, move them from kprobes.c
to inst.c, this is preparation for later patch, no functionality change.
Tested-by: Jeff Xie <xiehuan09@gmail.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Add guard for the larch_insn_gen_xxx functions to verify whether the
immediate operand is within the acceptable range.
Signed-off-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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According to LoongArch Reference Manual, simulate branch and PC*
instructions, this is preparation for later patch.
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#branch-instructions
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#_pcaddi_pcaddu121_pcaddu18l_pcalau12i
Tested-by: Jeff Xie <xiehuan09@gmail.com>
Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Simplify larch_insn_gen_xxx implementation by reusing emit_xxx.
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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This patch implements ftrace trampolines through plt entry.
Tested by forcing ftrace_make_call() to use the module PLT, and then
loading up a module after setting up ftrace with:
| echo ":mod:<module-name>" > set_ftrace_filter;
| echo function > current_tracer;
| modprobe <module-name>
Since FTRACE_ADDR/FTRACE_REGS_ADDR is only defined when CONFIG_DYNAMIC_
FTRACE is selected, we wrap their usage in module_init_ftrace_plt() with
ifdeffery rather than using IS_ENABLED().
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Once the function_graph tracer is enabled, a filtered function has the
following call sequence:
1) ftracer_caller ==> on/off by ftrace_make_call/ftrace_make_nop
2) ftrace_graph_caller
3) ftrace_graph_call ==> on/off by ftrace_en/disable_ftrace_graph_caller
4) prepare_ftrace_return
Considering the following DYNAMIC_FTRACE_WITH_REGS feature, it would be
more extendable to have a ftrace_graph_caller function, instead of
calling prepare_ftrace_return directly in ftrace_caller.
Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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The compiler has inserted 2 NOPs before the regular function prologue.
T series registers are available and safe because of LoongArch's psABI.
At runtime, we can replace nop with bl to enable ftrace call and replace
bl with nop to disable ftrace call. The bl instruction requires us to
save the original RA value, so it saves RA at t0 here.
Details are:
| Compiled | Disabled | Enabled |
+------------+------------------------+------------------------+
| nop | move t0, ra | move t0, ra |
| nop | nop | bl ftrace_caller |
| func_body | func_body | func_body |
The RA value will be recovered by ftrace_regs_entry, and restored into
RA before returning to the regular function prologue. When a function is
not being traced, the "move t0, ra" is not harmful.
1) ftrace_make_call, ftrace_make_nop (in kernel/ftrace.c)
The two functions turn each recorded call site of filtered functions
into a call to ftrace_caller or nops.
2) ftracce_update_ftrace_func (in kernel/ftrace.c)
turns the nops at ftrace_call into a call to a generic entry for
function tracers.
3) ftrace_caller (in kernel/mcount_dyn.S)
The entry where each _mcount call sites calls to once they are
filtered to be traced.
Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Add ELF-related definition and module relocation code for basic
LoongArch support.
Cc: Jessica Yu <jeyu@kernel.org>
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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