From: Usama Arif <usama.arif@bytedance.com>
To: dwmw2@infradead.org, tglx@linutronix.de, kim.phillips@amd.com,
brgerst@gmail.com
Cc: piotrgorski@cachyos.org, oleksandr@natalenko.name,
arjan@linux.intel.com, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org,
pbonzini@redhat.com, paulmck@kernel.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com,
thomas.lendacky@amd.com, seanjc@google.com,
pmenzel@molgen.mpg.de, fam.zheng@bytedance.com,
punit.agrawal@bytedance.com, simon.evans@bytedance.com,
liangma@liangbit.com, David Woodhouse <dwmw@amazon.co.uk>,
Usama Arif <usama.arif@bytedance.com>,
"Guilherme G . Piccoli" <gpiccoli@igalia.com>
Subject: [PATCH v14 08/12] x86/smpboot: Remove initial_gs
Date: Wed, 8 Mar 2023 17:13:24 +0000 [thread overview]
Message-ID: <20230308171328.1562857-9-usama.arif@bytedance.com> (raw)
In-Reply-To: <20230308171328.1562857-1-usama.arif@bytedance.com>
From: Brian Gerst <brgerst@gmail.com>
Given its CPU#, each CPU can find its own per-cpu offset, and directly set
GSBASE accordingly. The global variable can be eliminated.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Usama Arif <usama.arif@bytedance.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
---
arch/x86/include/asm/realmode.h | 1 -
arch/x86/kernel/acpi/sleep.c | 1 -
arch/x86/kernel/head_64.S | 22 ++++++++--------------
arch/x86/kernel/smpboot.c | 2 --
4 files changed, 8 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index a336feef0af1..f6a1737c77be 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -59,7 +59,6 @@ extern struct real_mode_header *real_mode_header;
extern unsigned char real_mode_blob_end[];
extern unsigned long initial_code;
-extern unsigned long initial_gs;
extern unsigned long initial_stack;
#ifdef CONFIG_AMD_MEM_ENCRYPT
extern unsigned long initial_vc_handler;
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index de89bb4719d0..1328c221af30 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -127,7 +127,6 @@ int x86_acpi_suspend_lowlevel(void)
* value is in the actual %rsp register.
*/
current->thread.sp = (unsigned long)temp_stack + sizeof(temp_stack);
- initial_gs = per_cpu_offset(smp_processor_id());
smpboot_control = smp_processor_id();
#endif
initial_code = (unsigned long)wakeup_long64;
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index a5b46c2fba05..6a8238702eab 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -66,18 +66,10 @@ SYM_CODE_START_NOALIGN(startup_64)
leaq _text(%rip), %rdi
- /*
- * initial_gs points to initial fixed_percpu_data struct with storage for
- * the stack protector canary. Global pointer fixups are needed at this
- * stage, so apply them as is done in fixup_pointer(), and initialize %gs
- * such that the canary can be accessed at %gs:40 for subsequent C calls.
- */
+ /* Setup GSBASE to allow stack canary access for C code */
movl $MSR_GS_BASE, %ecx
- movq initial_gs(%rip), %rax
- movq $_text, %rdx
- subq %rdx, %rax
- addq %rdi, %rax
- movq %rax, %rdx
+ leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
+ movl %edx, %eax
shrq $32, %rdx
wrmsr
@@ -294,8 +286,11 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
* the per cpu areas are set up.
*/
movl $MSR_GS_BASE,%ecx
- movl initial_gs(%rip),%eax
- movl initial_gs+4(%rip),%edx
+#ifndef CONFIG_SMP
+ leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
+#endif
+ movl %edx, %eax
+ shrq $32, %rdx
wrmsr
/* Setup and Load IDT */
@@ -437,7 +432,6 @@ SYM_CODE_END(vc_boot_ghcb)
__REFDATA
.balign 8
SYM_DATA(initial_code, .quad x86_64_start_kernel)
-SYM_DATA(initial_gs, .quad INIT_PER_CPU_VAR(fixed_percpu_data))
#ifdef CONFIG_AMD_MEM_ENCRYPT
SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb)
#endif
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index a22460a07cf8..b04520085582 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1084,8 +1084,6 @@ int common_cpu_up(unsigned int cpu, struct task_struct *idle)
#ifdef CONFIG_X86_32
/* Stack for startup_32 can be just as for start_secondary onwards */
per_cpu(pcpu_hot.top_of_stack, cpu) = task_top_of_stack(idle);
-#else
- initial_gs = per_cpu_offset(cpu);
#endif
return 0;
}
--
2.25.1
next prev parent reply other threads:[~2023-03-08 17:15 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-08 17:13 [PATCH v14 00/12] Parallel CPU bringup for x86_64 Usama Arif
2023-03-08 17:13 ` [PATCH v14 01/12] x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel Usama Arif
2023-03-08 17:13 ` [PATCH v14 02/12] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> Usama Arif
2023-03-08 17:13 ` [PATCH v14 03/12] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Usama Arif
2023-03-08 17:13 ` [PATCH v14 04/12] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Usama Arif
2023-03-08 17:13 ` [PATCH v14 05/12] x86/smpboot: Split up native_cpu_up into separate phases and document them Usama Arif
2023-03-11 9:19 ` Thomas Gleixner
2023-03-11 10:21 ` David Woodhouse
2023-03-08 17:13 ` [PATCH v14 06/12] x86/smpboot: Remove initial_stack on 64-bit Usama Arif
2023-03-08 17:13 ` [PATCH v14 07/12] x86/smpboot: Remove early_gdt_descr " Usama Arif
2023-03-08 17:13 ` Usama Arif [this message]
2023-03-08 17:13 ` [PATCH v14 09/12] x86/smpboot: Support parallel startup of secondary CPUs Usama Arif
2023-03-13 22:21 ` Brian Gerst
2023-03-08 17:13 ` [PATCH v14 10/12] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Usama Arif
2023-03-11 8:54 ` Thomas Gleixner
2023-03-11 9:55 ` David Woodhouse
2023-03-11 14:14 ` Thomas Gleixner
2023-03-11 14:25 ` David Woodhouse
2023-03-11 10:17 ` David Woodhouse
2023-03-08 17:13 ` [PATCH v14 11/12] x86/smpboot: Serialize topology updates for secondary bringup Usama Arif
2023-03-08 17:13 ` [PATCH v14 12/12] x86/smpboot: Allow parallel bringup for SEV-ES Usama Arif
2023-03-10 19:20 ` [PATCH v14 00/12] Parallel CPU bringup for x86_64 Tor Vic
2023-03-10 20:18 ` Paul Menzel
2023-03-11 19:23 ` Tor Vic
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