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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Jun 2025 18:00:56.3100 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 02dd6d99-256a-46c2-22ff-08dda848bfb1 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL02EPF00029929.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB8599 Content-Type: text/plain; charset="utf-8" Define apic_page construct to unionize apic register 32bit/64bit accesses and use it in apic_{get|set}*() to avoid using type casting. One caveat of this change is that the generated code is slighly larger. Below is the code generation for apic_get_reg() using gcc-14.2: - Without change: apic_get_reg: 89 f6 mov %esi,%esi 8b 04 37 mov (%rdi,%rsi,1),%eax c3 ret - With change: apic_get_reg: c1 ee 02 shr $0x2,%esi 8b 04 b7 mov (%rdi,%rsi,4),%eax c3 ret lapic.o text size change is shown below: Obj Old-size New-size lapic.o 28800 28832 Signed-off-by: Neeraj Upadhyay --- Changes since v6: - Converted assmebly to AT&T format. - Added details about overall size change in commit log. arch/x86/include/asm/apic.h | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 07ba4935e873..b7cbe9ba363e 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -525,26 +525,43 @@ static inline int apic_find_highest_vector(void *bitm= ap) return -1; } =20 +struct apic_page { + union { + u64 regs64[PAGE_SIZE / 8]; + u32 regs[PAGE_SIZE / 4]; + u8 bytes[PAGE_SIZE]; + }; +} __aligned(PAGE_SIZE); + static inline u32 apic_get_reg(void *regs, int reg) { - return *((u32 *) (regs + reg)); + struct apic_page *ap =3D regs; + + return ap->regs[reg / 4]; } =20 static inline void apic_set_reg(void *regs, int reg, u32 val) { - *((u32 *) (regs + reg)) =3D val; + struct apic_page *ap =3D regs; + + ap->regs[reg / 4] =3D val; } =20 static __always_inline u64 apic_get_reg64(void *regs, int reg) { + struct apic_page *ap =3D regs; + BUILD_BUG_ON(reg !=3D APIC_ICR); - return *((u64 *) (regs + reg)); + + return ap->regs64[reg / 8]; } =20 static __always_inline void apic_set_reg64(void *regs, int reg, u64 val) { + struct apic_page *ap =3D regs; + BUILD_BUG_ON(reg !=3D APIC_ICR); - *((u64 *) (regs + reg)) =3D val; + ap->regs64[reg / 8] =3D val; } =20 static inline void apic_clear_vector(int vec, void *bitmap) --=20 2.34.1