On Thu, Jun 13, 2024 at 03:11:08PM +0800, Andy Chiu wrote:
> Some caller-saved registers which are not defined as function arguments
> in the ABI can still be passed as arguments when the kernel is compiled
> with Clang. As a result, we must save and restore those registers to
> prevent ftrace from clobbering them.
>
> - [1]: https://reviews.llvm.org/D68559
> Reported-by: Evgenii Shatokhin <e.shatok...@yadro.com>
> Closes:
> https://lore.kernel.org/linux-riscv/7e7c7914-445d-426d-89a0-59a9199c4...@yadro.com/
> Signed-off-by: Andy Chiu <andy.c...@sifive.com>
Acked-by: Nathan Chancellor <nat...@kernel.org>
> ---
> arch/riscv/include/asm/ftrace.h | 7 +++++++
> arch/riscv/kernel/asm-offsets.c | 7 +++++++
> arch/riscv/kernel/mcount-dyn.S | 16 ++++++++++++++--
> 3 files changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
> index 9eb31a7ea0aa..5f81c53dbfd9 100644
> --- a/arch/riscv/include/asm/ftrace.h
> +++ b/arch/riscv/include/asm/ftrace.h
> @@ -144,6 +144,13 @@ struct ftrace_regs {
> unsigned long a5;
> unsigned long a6;
> unsigned long a7;
> +#ifdef CONFIG_CC_IS_CLANG
> + unsigned long t2;
> + unsigned long t3;
> + unsigned long t4;
> + unsigned long t5;
> + unsigned long t6;
> +#endif
> };
> };
> };
> diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
> index b09ca5f944f7..db5a26fcc9ae 100644
> --- a/arch/riscv/kernel/asm-offsets.c
> +++ b/arch/riscv/kernel/asm-offsets.c
> @@ -497,6 +497,13 @@ void asm_offsets(void)
> DEFINE(FREGS_SP, offsetof(struct ftrace_regs, sp));
> DEFINE(FREGS_S0, offsetof(struct ftrace_regs, s0));
> DEFINE(FREGS_T1, offsetof(struct ftrace_regs, t1));
> +#ifdef CONFIG_CC_IS_CLANG
> + DEFINE(FREGS_T2, offsetof(struct ftrace_regs, t2));
> + DEFINE(FREGS_T3, offsetof(struct ftrace_regs, t3));
> + DEFINE(FREGS_T4, offsetof(struct ftrace_regs, t4));
> + DEFINE(FREGS_T5, offsetof(struct ftrace_regs, t5));
> + DEFINE(FREGS_T6, offsetof(struct ftrace_regs, t6));
> +#endif
> DEFINE(FREGS_A0, offsetof(struct ftrace_regs, a0));
> DEFINE(FREGS_A1, offsetof(struct ftrace_regs, a1));
> DEFINE(FREGS_A2, offsetof(struct ftrace_regs, a2));
> diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
> index 745dd4c4a69c..e988bd26b28b 100644
> --- a/arch/riscv/kernel/mcount-dyn.S
> +++ b/arch/riscv/kernel/mcount-dyn.S
> @@ -96,7 +96,13 @@
> REG_S x8, FREGS_S0(sp)
> #endif
> REG_S x6, FREGS_T1(sp)
> -
> +#ifdef CONFIG_CC_IS_CLANG
> + REG_S x7, FREGS_T2(sp)
> + REG_S x28, FREGS_T3(sp)
> + REG_S x29, FREGS_T4(sp)
> + REG_S x30, FREGS_T5(sp)
> + REG_S x31, FREGS_T6(sp)
> +#endif
> // save the arguments
> REG_S x10, FREGS_A0(sp)
> REG_S x11, FREGS_A1(sp)
> @@ -115,7 +121,13 @@
> REG_L x8, FREGS_S0(sp)
> #endif
> REG_L x6, FREGS_T1(sp)
> -
> +#ifdef CONFIG_CC_IS_CLANG
> + REG_L x7, FREGS_T2(sp)
> + REG_L x28, FREGS_T3(sp)
> + REG_L x29, FREGS_T4(sp)
> + REG_L x30, FREGS_T5(sp)
> + REG_L x31, FREGS_T6(sp)
> +#endif
> // restore the arguments
> REG_L x10, FREGS_A0(sp)
> REG_L x11, FREGS_A1(sp)
>
> --
> 2.43.0
>
