Re: [PATCH v2 3/7] syscall.h: add syscall_set_arguments() and syscall_set_return_value()

[Charlie Jenkins <charlie@rivosinc.com>]

On Mon, Jan 13, 2025 at 07:11:40PM +0200, Dmitry V. Levin wrote:
> These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
> architectures to implement PTRACE_SET_SYSCALL_INFO API.
> 
> This partially reverts commit 7962c2eddbfe ("arch: remove unused
> function syscall_set_arguments()") by reusing some of old
> syscall_set_arguments() implementations.
> 
> Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> ---
> 
> Note that I'm not a MIPS expert, I just added mips_set_syscall_arg() by
> looking at mips_get_syscall_arg() and the result passes tests in qemu on
> mips O32, mips64 O32, mips64 N32, and mips64 N64.
> 
>  arch/arc/include/asm/syscall.h        | 14 +++++++++++
>  arch/arm/include/asm/syscall.h        | 13 ++++++++++
>  arch/arm64/include/asm/syscall.h      | 13 ++++++++++
>  arch/csky/include/asm/syscall.h       | 13 ++++++++++
>  arch/hexagon/include/asm/syscall.h    | 14 +++++++++++
>  arch/loongarch/include/asm/syscall.h  |  8 ++++++
>  arch/mips/include/asm/syscall.h       | 32 ++++++++++++++++++++++++
>  arch/nios2/include/asm/syscall.h      | 11 ++++++++
>  arch/openrisc/include/asm/syscall.h   |  7 ++++++
>  arch/parisc/include/asm/syscall.h     | 12 +++++++++
>  arch/powerpc/include/asm/syscall.h    | 10 ++++++++
>  arch/riscv/include/asm/syscall.h      |  9 +++++++
>  arch/s390/include/asm/syscall.h       | 12 +++++++++
>  arch/sh/include/asm/syscall_32.h      | 12 +++++++++
>  arch/sparc/include/asm/syscall.h      | 10 ++++++++
>  arch/um/include/asm/syscall-generic.h | 14 +++++++++++
>  arch/x86/include/asm/syscall.h        | 36 +++++++++++++++++++++++++++
>  arch/xtensa/include/asm/syscall.h     | 11 ++++++++
>  include/asm-generic/syscall.h         | 16 ++++++++++++
>  19 files changed, 267 insertions(+)
> 
> diff --git a/arch/arc/include/asm/syscall.h b/arch/arc/include/asm/syscall.h
> index 9709256e31c8..89c1e1736356 100644
> --- a/arch/arc/include/asm/syscall.h
> +++ b/arch/arc/include/asm/syscall.h
> @@ -67,6 +67,20 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>  	}
>  }
>  
> +static inline void
> +syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +		      unsigned long *args)
> +{
> +	unsigned long *inside_ptregs = &regs->r0;
> +	unsigned int n = 6;
> +	unsigned int i = 0;
> +
> +	while (n--) {
> +		*inside_ptregs = args[i++];
> +		inside_ptregs--;
> +	}
> +}
> +
>  static inline int
>  syscall_get_arch(struct task_struct *task)
>  {
> diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
> index fe4326d938c1..21927fa0ae2b 100644
> --- a/arch/arm/include/asm/syscall.h
> +++ b/arch/arm/include/asm/syscall.h
> @@ -80,6 +80,19 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	memcpy(args, &regs->ARM_r0 + 1, 5 * sizeof(args[0]));
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	memcpy(&regs->ARM_r0, args, 6 * sizeof(args[0]));
> +	/*
> +	 * Also copy the first argument into ARM_ORIG_r0
> +	 * so that syscall_get_arguments() would return it
> +	 * instead of the previous value.
> +	 */
> +	regs->ARM_ORIG_r0 = regs->ARM_r0;
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	/* ARM tasks don't change audit architectures on the fly. */
> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> index ab8e14b96f68..76020b66286b 100644
> --- a/arch/arm64/include/asm/syscall.h
> +++ b/arch/arm64/include/asm/syscall.h
> @@ -73,6 +73,19 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	memcpy(args, &regs->regs[1], 5 * sizeof(args[0]));
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	memcpy(&regs->regs[0], args, 6 * sizeof(args[0]));
> +	/*
> +	 * Also copy the first argument into orig_x0
> +	 * so that syscall_get_arguments() would return it
> +	 * instead of the previous value.
> +	 */
> +	regs->orig_x0 = regs->regs[0];
> +}
> +
>  /*
>   * We don't care about endianness (__AUDIT_ARCH_LE bit) here because
>   * AArch64 has the same system calls both on little- and big- endian.
> diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
> index 0de5734950bf..30403f7a0487 100644
> --- a/arch/csky/include/asm/syscall.h
> +++ b/arch/csky/include/asm/syscall.h
> @@ -59,6 +59,19 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>  	memcpy(args, &regs->a1, 5 * sizeof(args[0]));
>  }
>  
> +static inline void
> +syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +		      const unsigned long *args)
> +{
> +	memcpy(&regs->a0, args, 6 * sizeof(regs->a0));
> +	/*
> +	 * Also copy the first argument into orig_x0
> +	 * so that syscall_get_arguments() would return it
> +	 * instead of the previous value.
> +	 */
> +	regs->orig_a0 = regs->a0;
> +}
> +
>  static inline int
>  syscall_get_arch(struct task_struct *task)
>  {
> diff --git a/arch/hexagon/include/asm/syscall.h b/arch/hexagon/include/asm/syscall.h
> index f6e454f18038..1024a6548d78 100644
> --- a/arch/hexagon/include/asm/syscall.h
> +++ b/arch/hexagon/include/asm/syscall.h
> @@ -33,6 +33,13 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	memcpy(args, &(&regs->r00)[0], 6 * sizeof(args[0]));
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	memcpy(&(&regs->r00)[0], args, 6 * sizeof(args[0]));
> +}
> +
>  static inline long syscall_get_error(struct task_struct *task,
>  				     struct pt_regs *regs)
>  {
> @@ -45,6 +52,13 @@ static inline long syscall_get_return_value(struct task_struct *task,
>  	return regs->r00;
>  }
>  
> +static inline void syscall_set_return_value(struct task_struct *task,
> +					    struct pt_regs *regs,
> +					    int error, long val)
> +{
> +	regs->r00 = (long) error ?: val;
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	return AUDIT_ARCH_HEXAGON;
> diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h
> index e286dc58476e..ff415b3c0a8e 100644
> --- a/arch/loongarch/include/asm/syscall.h
> +++ b/arch/loongarch/include/asm/syscall.h
> @@ -61,6 +61,14 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	memcpy(&args[1], &regs->regs[5], 5 * sizeof(long));
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	regs->orig_a0 = args[0];
> +	memcpy(&regs->regs[5], &args[1], 5 * sizeof(long));
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	return AUDIT_ARCH_LOONGARCH64;
> diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
> index 2f85f2d8f754..3163d1506fae 100644
> --- a/arch/mips/include/asm/syscall.h
> +++ b/arch/mips/include/asm/syscall.h
> @@ -76,6 +76,23 @@ static inline void mips_get_syscall_arg(unsigned long *arg,
>  #endif
>  }
>  
> +static inline void mips_set_syscall_arg(unsigned long *arg,
> +	struct task_struct *task, struct pt_regs *regs, unsigned int n)
> +{
> +#ifdef CONFIG_32BIT
> +	switch (n) {
> +	case 0: case 1: case 2: case 3:
> +		regs->regs[4 + n] = *arg;
> +		return;
> +	case 4: case 5: case 6: case 7:
> +		*arg = regs->pad0[n] = *arg;
> +		return;
> +	}
> +#else
> +	regs->regs[4 + n] = *arg;
> +#endif
> +}
> +
>  static inline long syscall_get_error(struct task_struct *task,
>  				     struct pt_regs *regs)
>  {
> @@ -122,6 +139,21 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  		mips_get_syscall_arg(args++, task, regs, i++);
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	unsigned int i = 0;
> +	unsigned int n = 6;
> +
> +	/* O32 ABI syscall() */
> +	if (mips_syscall_is_indirect(task, regs))
> +		i++;
> +
> +	while (n--)
> +		mips_set_syscall_arg(args++, task, regs, i++);
> +}
> +
>  extern const unsigned long sys_call_table[];
>  extern const unsigned long sys32_call_table[];
>  extern const unsigned long sysn32_call_table[];
> diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h
> index fff52205fb65..526449edd768 100644
> --- a/arch/nios2/include/asm/syscall.h
> +++ b/arch/nios2/include/asm/syscall.h
> @@ -58,6 +58,17 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	*args   = regs->r9;
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +	struct pt_regs *regs, const unsigned long *args)
> +{
> +	regs->r4 = *args++;
> +	regs->r5 = *args++;
> +	regs->r6 = *args++;
> +	regs->r7 = *args++;
> +	regs->r8 = *args++;
> +	regs->r9 = *args;
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	return AUDIT_ARCH_NIOS2;
> diff --git a/arch/openrisc/include/asm/syscall.h b/arch/openrisc/include/asm/syscall.h
> index 903ed882bdec..e6383be2a195 100644
> --- a/arch/openrisc/include/asm/syscall.h
> +++ b/arch/openrisc/include/asm/syscall.h
> @@ -57,6 +57,13 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>  	memcpy(args, &regs->gpr[3], 6 * sizeof(args[0]));
>  }
>  
> +static inline void
> +syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +		      const unsigned long *args)
> +{
> +	memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	return AUDIT_ARCH_OPENRISC;
> diff --git a/arch/parisc/include/asm/syscall.h b/arch/parisc/include/asm/syscall.h
> index 00b127a5e09b..b146d0ae4c77 100644
> --- a/arch/parisc/include/asm/syscall.h
> +++ b/arch/parisc/include/asm/syscall.h
> @@ -29,6 +29,18 @@ static inline void syscall_get_arguments(struct task_struct *tsk,
>  	args[0] = regs->gr[26];
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *tsk,
> +					 struct pt_regs *regs,
> +					 unsigned long *args)
> +{
> +	regs->gr[21] = args[5];
> +	regs->gr[22] = args[4];
> +	regs->gr[23] = args[3];
> +	regs->gr[24] = args[2];
> +	regs->gr[25] = args[1];
> +	regs->gr[26] = args[0];
> +}
> +
>  static inline long syscall_get_error(struct task_struct *task,
>  				     struct pt_regs *regs)
>  {
> diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
> index 422d7735ace6..521f279e6b33 100644
> --- a/arch/powerpc/include/asm/syscall.h
> +++ b/arch/powerpc/include/asm/syscall.h
> @@ -114,6 +114,16 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	}
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));
> +
> +	/* Also copy the first argument into orig_gpr3 */
> +	regs->orig_gpr3 = args[0];
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	if (is_tsk_32bit_task(task))
> diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
> index 121fff429dce..8d389ba995c8 100644
> --- a/arch/riscv/include/asm/syscall.h
> +++ b/arch/riscv/include/asm/syscall.h
> @@ -66,6 +66,15 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	memcpy(args, &regs->a1, 5 * sizeof(args[0]));
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	regs->orig_a0 = args[0];
> +	args++;
> +	memcpy(&regs->a1, args, 5 * sizeof(regs->a1));
> +}

Looks good for riscv.

Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com

> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  #ifdef CONFIG_64BIT
> diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
> index 27e3d804b311..b3dd883699e7 100644
> --- a/arch/s390/include/asm/syscall.h
> +++ b/arch/s390/include/asm/syscall.h
> @@ -78,6 +78,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	args[0] = regs->orig_gpr2 & mask;
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	unsigned int n = 6;
> +
> +	while (n-- > 0)
> +		if (n > 0)
> +			regs->gprs[2 + n] = args[n];
> +	regs->orig_gpr2 = args[0];
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  #ifdef CONFIG_COMPAT
> diff --git a/arch/sh/include/asm/syscall_32.h b/arch/sh/include/asm/syscall_32.h
> index d87738eebe30..cb51a7528384 100644
> --- a/arch/sh/include/asm/syscall_32.h
> +++ b/arch/sh/include/asm/syscall_32.h
> @@ -57,6 +57,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	args[0] = regs->regs[4];
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	regs->regs[1] = args[5];
> +	regs->regs[0] = args[4];
> +	regs->regs[7] = args[3];
> +	regs->regs[6] = args[2];
> +	regs->regs[5] = args[1];
> +	regs->regs[4] = args[0];
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	int arch = AUDIT_ARCH_SH;
> diff --git a/arch/sparc/include/asm/syscall.h b/arch/sparc/include/asm/syscall.h
> index 20c109ac8cc9..62a5a78804c4 100644
> --- a/arch/sparc/include/asm/syscall.h
> +++ b/arch/sparc/include/asm/syscall.h
> @@ -117,6 +117,16 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	}
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < 6; i++)
> +		regs->u_regs[UREG_I0 + i] = args[i];
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  #if defined(CONFIG_SPARC64) && defined(CONFIG_COMPAT)
> diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
> index 172b74143c4b..2984feb9d576 100644
> --- a/arch/um/include/asm/syscall-generic.h
> +++ b/arch/um/include/asm/syscall-generic.h
> @@ -62,6 +62,20 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	*args   = UPT_SYSCALL_ARG6(r);
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	struct uml_pt_regs *r = &regs->regs;
> +
> +	UPT_SYSCALL_ARG1(r) = *args++;
> +	UPT_SYSCALL_ARG2(r) = *args++;
> +	UPT_SYSCALL_ARG3(r) = *args++;
> +	UPT_SYSCALL_ARG4(r) = *args++;
> +	UPT_SYSCALL_ARG5(r) = *args++;
> +	UPT_SYSCALL_ARG6(r) = *args;
> +}
> +
>  /* See arch/x86/um/asm/syscall.h for syscall_get_arch() definition. */
>  
>  #endif	/* __UM_SYSCALL_GENERIC_H */
> diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
> index 7c488ff0c764..b9c249dd9e3d 100644
> --- a/arch/x86/include/asm/syscall.h
> +++ b/arch/x86/include/asm/syscall.h
> @@ -90,6 +90,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	args[5] = regs->bp;
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	regs->bx = args[0];
> +	regs->cx = args[1];
> +	regs->dx = args[2];
> +	regs->si = args[3];
> +	regs->di = args[4];
> +	regs->bp = args[5];
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	return AUDIT_ARCH_I386;
> @@ -121,6 +133,30 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	}
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +# ifdef CONFIG_IA32_EMULATION
> +	if (task->thread_info.status & TS_COMPAT) {
> +		regs->bx = *args++;
> +		regs->cx = *args++;
> +		regs->dx = *args++;
> +		regs->si = *args++;
> +		regs->di = *args++;
> +		regs->bp = *args;
> +	} else
> +# endif
> +	{
> +		regs->di = *args++;
> +		regs->si = *args++;
> +		regs->dx = *args++;
> +		regs->r10 = *args++;
> +		regs->r8 = *args++;
> +		regs->r9 = *args;
> +	}
> +}
> +
>  static inline int syscall_get_arch(struct task_struct *task)
>  {
>  	/* x32 tasks should be considered AUDIT_ARCH_X86_64. */
> diff --git a/arch/xtensa/include/asm/syscall.h b/arch/xtensa/include/asm/syscall.h
> index 5ee974bf8330..f9a671cbf933 100644
> --- a/arch/xtensa/include/asm/syscall.h
> +++ b/arch/xtensa/include/asm/syscall.h
> @@ -68,6 +68,17 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  		args[i] = regs->areg[reg[i]];
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	static const unsigned int reg[] = XTENSA_SYSCALL_ARGUMENT_REGS;
> +	unsigned int i;
> +
> +	for (i = 0; i < 6; ++i)
> +		regs->areg[reg[i]] = args[i];
> +}
> +
>  asmlinkage long xtensa_rt_sigreturn(void);
>  asmlinkage long xtensa_shmat(int, char __user *, int);
>  asmlinkage long xtensa_fadvise64_64(int, int,
> diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
> index 5a80fe728dc8..0f7b9a493de7 100644
> --- a/include/asm-generic/syscall.h
> +++ b/include/asm-generic/syscall.h
> @@ -117,6 +117,22 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
>  void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>  			   unsigned long *args);
>  
> +/**
> + * syscall_set_arguments - change system call parameter value
> + * @task:	task of interest, must be in system call entry tracing
> + * @regs:	task_pt_regs() of @task
> + * @args:	array of argument values to store
> + *
> + * Changes 6 arguments to the system call.
> + * The first argument gets value @args[0], and so on.
> + *
> + * It's only valid to call this when @task is stopped for tracing on
> + * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
> + * %SYSCALL_WORK_SYSCALL_AUDIT.
> + */
> +void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
> +			   const unsigned long *args);
> +
>  /**
>   * syscall_get_arch - return the AUDIT_ARCH for the current system call
>   * @task:	task of interest, must be blocked
> -- 
> ldv