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Re: [PATCH] x86/idt: Minor improvements to _update_gate_addr_lower()
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 12 May 2025 15:21:07 +0200
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- Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Mon, 12 May 2025 13:21:20 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 12.05.2025 13:58, Andrew Cooper wrote:
> --- a/xen/arch/x86/include/asm/idt.h
> +++ b/xen/arch/x86/include/asm/idt.h
> @@ -92,15 +92,16 @@ static inline void _set_gate_lower(idt_entry_t *gate,
> unsigned long type,
> * Update the lower half handler of an IDT entry, without changing any other
> * configuration.
> */
> -static inline void _update_gate_addr_lower(idt_entry_t *gate, void *addr)
> +static inline void _update_gate_addr_lower(idt_entry_t *gate, void *_addr)
Considering comment and name of the function, ...
> {
> + unsigned long addr = (unsigned long)_addr;
> + unsigned int addr1 = addr & 0xffff0000U; /* GCC force better codegen. */
> idt_entry_t idte;
> - idte.a = gate->a;
>
> - idte.b = ((unsigned long)(addr) >> 32);
> - idte.a &= 0x0000FFFFFFFF0000ULL;
> - idte.a |= (((unsigned long)(addr) & 0xFFFF0000UL) << 32) |
> - ((unsigned long)(addr) & 0xFFFFUL);
> + idte.b = addr >> 32;
... doesn't this line want dropping altogether? Or at best be an assertion?
Jan
> + idte.a = gate->a & 0x0000ffffffff0000UL;
> + idte.a |= (unsigned long)addr1 << 32;
> + idte.a |= addr & 0xffff;
>
> _write_gate_lower(gate, &idte);
> }
|
