linux-dev/arch/riscv/kernel/ftrace.c, branch linus/master

ftrace: Remove return value of ftrace_arch_modify_*()

2022-05-27T01:13:00Z

All instances of the function ftrace_arch_modify_prepare() and ftrace_arch_modify_post_process() return zero. There's no point in checking their return value. Just have them be void functions. Link: https://lkml.kernel.org/r/20220518023639.4065-1-kunyu@nfschina.com Signed-off-by: Li kunyu Signed-off-by: Steven Rostedt (Google)

ftrace: Cleanup ftrace_dyn_arch_init()

2021-10-08T23:41:39Z

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 (s390) Acked-by: Helge Deller (parisc) Signed-off-by: Weizhao Ouyang Signed-off-by: Steven Rostedt (VMware)

riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT

2021-01-14T23:09:05Z

This patch changes the current detour mechanism of dynamic ftrace which has been discussed during LPC 2020 RISCV-MC [1]. Before the patch, we used mcount for detour: : addi sp,sp,-16 sd ra,8(sp) sd s0,0(sp) addi s0,sp,16 mv a5,ra mv a0,a5 auipc ra,0x0 -> nop jalr -296(ra) <_mcount@plt> ->nop ... After the patch, we use nop call site area for detour: : nop -> REG_S ra, -SZREG(sp) nop -> auipc ra, 0x? nop -> jalr ?(ra) nop -> REG_L ra, -SZREG(sp) ... The mcount mechanism is mixed with gcc function prologue which is not very clear. The patchable function entry just put 16 bytes nop before the front of the function prologue which could be filled with a separated detour mechanism. [1] https://www.linuxplumbersconf.org/event/7/contributions/807/ Signed-off-by: Guo Ren Signed-off-by: Palmer Dabbelt

risc-v: kernel: ftrace: Fixes improper SPDX comment style

2020-11-04T21:28:20Z

Signed-off-by: Ryan Kosta Signed-off-by: Palmer Dabbelt

RISC-V: Take text_mutex in ftrace_init_nop()

2020-09-11T19:15:21Z

Without this we get lockdep failures. They're spurious failures as SMP isn't up when ftrace_init_nop() is called. As far as I can tell the easiest fix is to just take the lock, which also seems like the safest fix. Signed-off-by: Palmer Dabbelt Acked-by: Guo Ren Signed-off-by: Palmer Dabbelt

maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

2020-06-17T17:57:41Z

Better describe what these functions do. Suggested-by: Linus Torvalds Signed-off-by: Christoph Hellwig Signed-off-by: Linus Torvalds

riscv: Use text_mutex instead of patch_lock

2020-05-18T18:38:16Z

We don't need the additional lock protection when patching the text. There are two patching interfaces here: - patch_text: patch code and always synchronize with stop_machine() - patch_text_nosync: patch code without synchronization, it's caller's responsibility to synchronize all CPUs if needed. For the first one, stop_machine() is protected by its own mutex, and also the irq is already disabled here. For the second one, in risc-v real case now, it would be used to ftrace patching the mcount function, since it already running under kstop_machine(), no other thread will run, so we could use text_mutex on ftrace side. Signed-off-by: Zong Li Reviewed-by: Masami Hiramatsu Reviewed-by: Palmer Dabbelt Signed-off-by: Palmer Dabbelt

riscv: Remove the 'riscv_' prefix of function name

2020-05-18T18:38:13Z

Refactor the function name by removing the 'riscv_' prefix, it would be better unless it could mix up with arch-independent functions. Signed-off-by: Zong Li Reviewed-by: Masami Hiramatsu Reviewed-by: Palmer Dabbelt Signed-off-by: Palmer Dabbelt

riscv: patch code by fixmap mapping

2020-03-26T16:24:55Z

On strict kernel memory permission, the ftrace have to change the permission of text for dynamic patching the intructions. Use riscv_patch_text_nosync() to patch code instead of probe_kernel_write. Signed-off-by: Zong Li Signed-off-by: Palmer Dabbelt

riscv: ftrace: correct the condition logic in function graph tracer

2020-01-03T08:56:37Z

The condition should be logical NOT to assign the hook address to parent address. Because the return value 0 of function_graph_enter upon success. Fixes: e949b6db51dc (riscv/function_graph: Simplify with function_graph_enter()) Signed-off-by: Zong Li Reviewed-by: Steven Rostedt (VMware) Cc: stable@vger.kernel.org Signed-off-by: Paul Walmsley