On Sun, Feb 21, 2021 at 12:25:54AM +0000, Sergei Trofimovich wrote:
> In https://bugs.gentoo.org/769614 Dmitry noticed that
> `ptrace(PTRACE_GET_SYSCALL_INFO)` does not return error sign properly.
>
> The bug is in mismatch between get/set errors:
>
> static inline long syscall_get_error(struct task_struct *task,
> struct pt_regs *regs)
> {
> return regs->r10 == -1 ? regs->r8:0;
> }
>
> static inline long syscall_get_return_value(struct task_struct *task,
> struct pt_regs *regs)
> {
> return regs->r8;
> }
>
> static inline void syscall_set_return_value(struct task_struct *task,
> struct pt_regs *regs,
> int error, long val)
> {
> if (error) {
> /* error < 0, but ia64 uses > 0 return value */
> regs->r8 = -error;
> regs->r10 = -1;
> } else {
> regs->r8 = val;
> regs->r10 = 0;
> }
> }
>
> Tested on v5.10 on rx3600 machine (ia64 9040 CPU).
>
> CC: linux-ia64@xxxxxxxxxxxxxxx
> CC: linux-kernel@xxxxxxxxxxxxxxx
> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Reported-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>
> Bug: https://bugs.gentoo.org/769614
> Signed-off-by: Sergei Trofimovich <slyfox@xxxxxxxxxx>
> ---
> arch/ia64/include/asm/syscall.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/ia64/include/asm/syscall.h b/arch/ia64/include/asm/syscall.h
> index 6c6f16e409a8..0d23c0049301 100644
> --- a/arch/ia64/include/asm/syscall.h
> +++ b/arch/ia64/include/asm/syscall.h
> @@ -32,7 +32,7 @@ static inline void syscall_rollback(struct task_struct *task,
> static inline long syscall_get_error(struct task_struct *task,
> struct pt_regs *regs)
> {
> - return regs->r10 == -1 ? regs->r8:0;
> + return regs->r10 == -1 ? -regs->r8:0;
> }
>
> static inline long syscall_get_return_value(struct task_struct *task,
Reviewed-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>
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