riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support

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Select the DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide the
register_ftrace_direct[_multi] interfaces allowing users to register
the customed trampoline (direct_caller) as the mcount for one or more
target functions. And modify_ftrace_direct[_multi] are also provided
for modifying direct_caller.

To make the direct_caller and the other ftrace hooks (e.g.
function/fgraph tracer, k[ret]probes) co-exist, a temporary register
is nominated to store the address of direct_caller in
ftrace_regs_caller. After the setting of the address direct_caller by
direct_ops->func and the RESTORE_REGS in ftrace_regs_caller,
direct_caller will be jumped to by the `jr` inst.

Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support for RISC-V.

Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
Acked-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20231130121531.1178502-4-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

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Song Shuai 2023-11-30 13:15:30 +01:00 • committed by Palmer Dabbelt

parent 35e61e8827

commit 196c79f19a

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1

arch/riscv/Kconfig

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7

arch/riscv/include/asm/ftrace.h

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10

arch/riscv/kernel/mcount-dyn.S

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