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67a5ba8f74
Naresh Kamboju reported a "Bad frame pointer" kernel warning while
running LTP trace ftrace_stress_test.sh in riscv. We can reproduce the
same issue with the following command:
```
$ cd /sys/kernel/debug/tracing
$ echo 'f:myprobe do_nanosleep%return args1=$retval' > dynamic_events
$ echo 1 > events/fprobes/enable
$ echo 1 > tracing_on
$ sleep 1
```
And we can get the following kernel warning:
[ 127.692888] ------------[ cut here ]------------
[ 127.693755] Bad frame pointer: expected ff2000000065be50, received ba34c141e9594000
[ 127.693755] from func do_nanosleep return to ffffffff800ccb16
[ 127.698699] WARNING: CPU: 1 PID: 129 at kernel/trace/fgraph.c:755 ftrace_return_to_handler+0x1b2/0x1be
[ 127.699894] Modules linked in:
[ 127.700908] CPU: 1 UID: 0 PID: 129 Comm: sleep Not tainted 6.14.0-rc3-g0ab191c74642 #32
[ 127.701453] Hardware name: riscv-virtio,qemu (DT)
[ 127.701859] epc : ftrace_return_to_handler+0x1b2/0x1be
[ 127.702032] ra : ftrace_return_to_handler+0x1b2/0x1be
[ 127.702151] epc : ffffffff8013b5e0 ra : ffffffff8013b5e0 sp : ff2000000065bd10
[ 127.702221] gp : ffffffff819c12f8 tp : ff60000080853100 t0 : 6e00000000000000
[ 127.702284] t1 : 0000000000000020 t2 : 6e7566206d6f7266 s0 : ff2000000065bd80
[ 127.702346] s1 : ff60000081262000 a0 : 000000000000007b a1 : ffffffff81894f20
[ 127.702408] a2 : 0000000000000010 a3 : fffffffffffffffe a4 : 0000000000000000
[ 127.702470] a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
[ 127.702530] s2 : ba34c141e9594000 s3 : 0000000000000000 s4 : ff2000000065bdd0
[ 127.702591] s5 : 00007fff8adcf400 s6 : 000055556dc1d8c0 s7 : 0000000000000068
[ 127.702651] s8 : 00007fff8adf5d10 s9 : 000000000000006d s10: 0000000000000001
[ 127.702710] s11: 00005555737377c8 t3 : ffffffff819d899e t4 : ffffffff819d899e
[ 127.702769] t5 : ffffffff819d89a0 t6 : ff2000000065bb18
[ 127.702826] status: 0000000200000120 badaddr: 0000000000000000 cause: 0000000000000003
[ 127.703292] [<ffffffff8013b5e0>] ftrace_return_to_handler+0x1b2/0x1be
[ 127.703760] [<ffffffff80017bce>] return_to_handler+0x16/0x26
[ 127.704009] [<ffffffff80017bb8>] return_to_handler+0x0/0x26
[ 127.704057] [<ffffffff800d3352>] common_nsleep+0x42/0x54
[ 127.704117] [<ffffffff800d44a2>] __riscv_sys_clock_nanosleep+0xba/0x10a
[ 127.704176] [<ffffffff80901c56>] do_trap_ecall_u+0x188/0x218
[ 127.704295] [<ffffffff8090cc3e>] handle_exception+0x14a/0x156
[ 127.705436] ---[ end trace 0000000000000000 ]---
The reason is that the stack layout for constructing argument for the
ftrace_return_to_handler in the return_to_handler does not match the
__arch_ftrace_regs structure of riscv, leading to unexpected results.
Fixes: a3ed4157b7 ("fgraph: Replace fgraph_ret_regs with ftrace_regs")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/all/CA+G9fYvp_oAxeDFj88Tk2rfEZ7jtYKAKSwfYS66=57Db9TBdyA@mail.gmail.com
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250317031214.4138436-2-pulehui@huaweicloud.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
132 lines
2.8 KiB
ArmAsm
132 lines
2.8 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2017 Andes Technology Corporation */
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <linux/cfi_types.h>
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#include <linux/export.h>
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#include <asm/asm.h>
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#include <asm/csr.h>
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#include <asm/unistd.h>
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#include <asm/thread_info.h>
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#include <asm/asm-offsets.h>
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#include <asm/ftrace.h>
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.text
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.macro SAVE_ABI_STATE
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addi sp, sp, -16
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REG_S s0, 0*SZREG(sp)
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REG_S ra, 1*SZREG(sp)
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addi s0, sp, 16
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.endm
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/*
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* The call to ftrace_return_to_handler would overwrite the return
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* register if a0 was not saved.
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*/
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.macro SAVE_RET_ABI_STATE
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addi sp, sp, -FREGS_SIZE_ON_STACK
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REG_S ra, FREGS_RA(sp)
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REG_S s0, FREGS_S0(sp)
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REG_S a0, FREGS_A0(sp)
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REG_S a1, FREGS_A1(sp)
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addi s0, sp, FREGS_SIZE_ON_STACK
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.endm
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.macro RESTORE_ABI_STATE
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REG_L ra, 1*SZREG(sp)
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REG_L s0, 0*SZREG(sp)
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addi sp, sp, 16
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.endm
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.macro RESTORE_RET_ABI_STATE
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REG_L ra, FREGS_RA(sp)
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REG_L s0, FREGS_S0(sp)
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REG_L a0, FREGS_A0(sp)
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REG_L a1, FREGS_A1(sp)
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addi sp, sp, FREGS_SIZE_ON_STACK
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.endm
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SYM_TYPED_FUNC_START(ftrace_stub)
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#ifdef CONFIG_DYNAMIC_FTRACE
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.global _mcount
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.set _mcount, ftrace_stub
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#endif
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ret
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SYM_FUNC_END(ftrace_stub)
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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SYM_TYPED_FUNC_START(ftrace_stub_graph)
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ret
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SYM_FUNC_END(ftrace_stub_graph)
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SYM_FUNC_START(return_to_handler)
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/*
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* On implementing the frame point test, the ideal way is to compare the
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* s0 (frame pointer, if enabled) on entry and the sp (stack pointer) on return.
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* However, the psABI of variable-length-argument functions does not allow this.
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*
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* So alternatively we check the *old* frame pointer position, that is, the
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* value stored in -16(s0) on entry, and the s0 on return.
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*/
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SAVE_RET_ABI_STATE
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mv a0, sp
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call ftrace_return_to_handler
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mv a2, a0
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RESTORE_RET_ABI_STATE
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jalr a2
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SYM_FUNC_END(return_to_handler)
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#endif
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#ifndef CONFIG_DYNAMIC_FTRACE
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SYM_FUNC_START(_mcount)
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la t4, ftrace_stub
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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la t0, ftrace_graph_return
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REG_L t1, 0(t0)
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bne t1, t4, .Ldo_ftrace_graph_caller
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la t3, ftrace_graph_entry
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REG_L t2, 0(t3)
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la t6, ftrace_graph_entry_stub
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bne t2, t6, .Ldo_ftrace_graph_caller
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#endif
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la t3, ftrace_trace_function
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REG_L t5, 0(t3)
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bne t5, t4, .Ldo_trace
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ret
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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/*
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* A pseudo representation for the function graph tracer:
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* prepare_to_return(&ra_to_caller_of_caller, ra_to_caller)
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*/
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.Ldo_ftrace_graph_caller:
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addi a0, s0, -SZREG
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mv a1, ra
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#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
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REG_L a2, -2*SZREG(s0)
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#endif
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SAVE_ABI_STATE
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call prepare_ftrace_return
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RESTORE_ABI_STATE
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ret
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#endif
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/*
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* A pseudo representation for the function tracer:
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* (*ftrace_trace_function)(ra_to_caller, ra_to_caller_of_caller)
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*/
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.Ldo_trace:
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REG_L a1, -SZREG(s0)
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mv a0, ra
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SAVE_ABI_STATE
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jalr t5
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RESTORE_ABI_STATE
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ret
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SYM_FUNC_END(_mcount)
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#endif
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EXPORT_SYMBOL(_mcount)
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