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From: Ingo Molnar <mingo@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Borislav Petkov <bp@alien8.de>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 21/21] x86/entry: Clean up the SYSENTER_stack code
Date: Mon, 27 Nov 2017 11:45:29 +0100	[thread overview]
Message-ID: <20171127104529.12435-22-mingo@kernel.org> (raw)
In-Reply-To: <20171127104529.12435-1-mingo@kernel.org>

From: Andy Lutomirski <luto@kernel.org>

The existing code was a mess, mainly because C arrays are nasty.
Turn SYSENTER_stack into a struct, add a helper to find it, and do
all the obvious cleanups this enables.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Link: https://lkml.kernel.org/r/38ff640712c9b591b32de24a080daf13afaba234.1511497875.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/entry/entry_32.S        |  4 ++--
 arch/x86/entry/entry_64.S        |  2 +-
 arch/x86/include/asm/fixmap.h    |  5 +++++
 arch/x86/include/asm/processor.h |  6 +++++-
 arch/x86/kernel/asm-offsets.c    |  6 ++----
 arch/x86/kernel/cpu/common.c     | 14 +++-----------
 arch/x86/kernel/dumpstack.c      |  7 +++----
 7 files changed, 21 insertions(+), 23 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 0ab316c46806..3629bcbf85a2 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -942,7 +942,7 @@ ENTRY(debug)
 
 	/* Are we currently on the SYSENTER stack? */
 	movl	PER_CPU_VAR(cpu_entry_area), %ecx
-	addl	$CPU_ENTRY_AREA_tss + CPU_TSS_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
+	addl	$CPU_ENTRY_AREA_tss + TSS_STRUCT_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
 	subl	%eax, %ecx	/* ecx = (end of SYSENTER_stack) - esp */
 	cmpl	$SIZEOF_SYSENTER_stack, %ecx
 	jb	.Ldebug_from_sysenter_stack
@@ -986,7 +986,7 @@ ENTRY(nmi)
 
 	/* Are we currently on the SYSENTER stack? */
 	movl	PER_CPU_VAR(cpu_entry_area), %ecx
-	addl	$CPU_ENTRY_AREA_tss + CPU_TSS_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
+	addl	$CPU_ENTRY_AREA_tss + TSS_STRUCT_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
 	subl	%eax, %ecx	/* ecx = (end of SYSENTER_stack) - esp */
 	cmpl	$SIZEOF_SYSENTER_stack, %ecx
 	jb	.Lnmi_from_sysenter_stack
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 5e674b6362e3..caf74a1bb3de 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -158,7 +158,7 @@ END(native_usergs_sysret64)
 	_entry_trampoline - CPU_ENTRY_AREA_entry_trampoline(%rip)
 
 /* The top word of the SYSENTER stack is hot and is usable as scratch space. */
-#define RSP_SCRATCH	CPU_ENTRY_AREA_tss + CPU_TSS_SYSENTER_stack + \
+#define RSP_SCRATCH	CPU_ENTRY_AREA_tss + TSS_STRUCT_SYSENTER_stack + \
 			SIZEOF_SYSENTER_stack - 8 + CPU_ENTRY_AREA
 
 ENTRY(entry_SYSCALL_64_trampoline)
diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 81fdc405ab1f..5a1013df456e 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -237,5 +237,10 @@ static inline struct cpu_entry_area *get_cpu_entry_area(int cpu)
 	return (struct cpu_entry_area *)__fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0));
 }
 
+static inline struct SYSENTER_stack *cpu_SYSENTER_stack(int cpu)
+{
+	return &get_cpu_entry_area((cpu))->tss.SYSENTER_stack;
+}
+
 #endif /* !__ASSEMBLY__ */
 #endif /* _ASM_X86_FIXMAP_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 806011202733..0eb62e7eeb33 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -337,12 +337,16 @@ struct x86_hw_tss {
 #define IO_BITMAP_OFFSET		(offsetof(struct tss_struct, io_bitmap) - offsetof(struct tss_struct, x86_tss))
 #define INVALID_IO_BITMAP_OFFSET	0x8000
 
+struct SYSENTER_stack {
+	unsigned long		words[64];
+};
+
 struct tss_struct {
 	/*
 	 * Space for the temporary SYSENTER stack, used for SYSENTER
 	 * and the entry trampoline as well.
 	 */
-	unsigned long		SYSENTER_stack[64];
+	struct SYSENTER_stack	SYSENTER_stack;
 
 	/*
 	 * The fixed hardware portion.  This must not cross a page boundary
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 61b1af88ac07..46c0995344aa 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -94,10 +94,8 @@ void common(void) {
 	BLANK();
 	DEFINE(PTREGS_SIZE, sizeof(struct pt_regs));
 
-	/* Offset from cpu_tss to SYSENTER_stack */
-	OFFSET(CPU_TSS_SYSENTER_stack, tss_struct, SYSENTER_stack);
-	/* Size of SYSENTER_stack */
-	DEFINE(SIZEOF_SYSENTER_stack, sizeof(((struct tss_struct *)0)->SYSENTER_stack));
+	OFFSET(TSS_STRUCT_SYSENTER_stack, tss_struct, SYSENTER_stack);
+	DEFINE(SIZEOF_SYSENTER_stack, sizeof(struct SYSENTER_stack));
 
 	/* Layout info for cpu_entry_area */
 	OFFSET(CPU_ENTRY_AREA_tss, cpu_entry_area, tss);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f24d13cd73dc..1509f09abf5e 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1332,12 +1332,7 @@ void enable_sep_cpu(void)
 
 	tss->x86_tss.ss1 = __KERNEL_CS;
 	wrmsr(MSR_IA32_SYSENTER_CS, tss->x86_tss.ss1, 0);
-
-	wrmsr(MSR_IA32_SYSENTER_ESP,
-	      (unsigned long)&get_cpu_entry_area(cpu)->tss +
-	      offsetofend(struct tss_struct, SYSENTER_stack),
-	      0);
-
+	wrmsr(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_SYSENTER_stack(cpu) + 1), 0);
 	wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0);
 
 	put_cpu();
@@ -1454,9 +1449,7 @@ void syscall_init(void)
 	 * AMD doesn't allow SYSENTER in long mode (either 32- or 64-bit).
 	 */
 	wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
-	wrmsrl_safe(MSR_IA32_SYSENTER_ESP,
-		    (unsigned long)&get_cpu_entry_area(cpu)->tss +
-		    offsetofend(struct tss_struct, SYSENTER_stack));
+	wrmsrl_safe(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_SYSENTER_stack(cpu) + 1));
 	wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)entry_SYSENTER_compat);
 #else
 	wrmsrl(MSR_CSTAR, (unsigned long)ignore_sysret);
@@ -1673,8 +1666,7 @@ void cpu_init(void)
 	 */
 	set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss);
 	load_TR_desc();
-	load_sp0((unsigned long)&get_cpu_entry_area(cpu)->tss +
-		 offsetofend(struct tss_struct, SYSENTER_stack));
+	load_sp0((unsigned long)(cpu_SYSENTER_stack(cpu) + 1));
 
 	load_mm_ldt(&init_mm);
 
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 35876e94286d..f214f7a6ccad 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -45,11 +45,10 @@ bool in_task_stack(unsigned long *stack, struct task_struct *task,
 
 bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
 {
-	int cpu = smp_processor_id();
-	struct tss_struct *tss = &get_cpu_entry_area(cpu)->tss;
+	struct SYSENTER_stack *ss = cpu_SYSENTER_stack(smp_processor_id());
 
-	void *begin = &tss->SYSENTER_stack;
-	void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack);
+	void *begin = ss;
+	void *end = ss + 1;
 
 	if ((void *)stack < begin || (void *)stack >= end)
 		return false;
-- 
2.14.1

  parent reply	other threads:[~2017-11-27 10:46 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-27 10:45 [PATCH 00/21] Preparatory patches for x86 KAISER support Ingo Molnar
2017-11-27 10:45 ` [PATCH 01/21] x86/unwinder/orc: Don't bail on stack overflow Ingo Molnar
2017-11-27 14:47   ` Borislav Petkov
2017-11-27 10:45 ` [PATCH 02/21] x86/unwinder: Handle stack overflows more gracefully Ingo Molnar
2017-11-27 17:36   ` Borislav Petkov
2017-11-28  4:55     ` Josh Poimboeuf
2017-11-27 10:45 ` [PATCH 03/21] x86/irq: Remove an old outdated comment about context tracking races Ingo Molnar
2017-11-27 10:45 ` [PATCH 04/21] x86/irq/64: Print the offending IP in the stack overflow warning Ingo Molnar
2017-11-27 10:45 ` [PATCH 05/21] x86/entry/64: Allocate and enable the SYSENTER stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 06/21] x86/dumpstack: Add get_stack_info() support for " Ingo Molnar
2017-11-27 10:45 ` [PATCH 07/21] x86/entry/gdt: Put per-CPU GDT remaps in ascending order Ingo Molnar
2017-11-27 10:45 ` [PATCH 08/21] x86/mm/fixmap: Generalize the GDT fixmap mechanism, introduce 'struct cpu_entry_area' Ingo Molnar
2017-11-27 10:45 ` [PATCH 09/21] x86/kasan/64: Teach KASAN about the cpu_entry_area Ingo Molnar
2017-11-27 10:45 ` [PATCH 10/21] x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss Ingo Molnar
2017-11-27 10:45 ` [PATCH 11/21] x86/dumpstack: Handle stack overflow on all stacks Ingo Molnar
2017-11-27 19:26   ` Linus Torvalds
2017-11-28  4:29     ` Josh Poimboeuf
2017-11-28  5:29       ` Andy Lutomirski
2017-11-28 18:15         ` Josh Poimboeuf
2017-11-27 10:45 ` [PATCH 12/21] x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct Ingo Molnar
2017-11-27 10:45 ` [PATCH 13/21] x86/entry: Remap the TSS into the CPU entry area Ingo Molnar
2017-11-27 10:45 ` [PATCH 14/21] x86/entry/64: Separate cpu_current_top_of_stack from TSS.sp0 Ingo Molnar
2017-11-27 10:45 ` [PATCH 15/21] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 16/21] x86/entry/64: Use a per-CPU trampoline stack for IDT entries Ingo Molnar
2017-12-01 17:06   ` Dave Hansen
2017-12-01 17:44     ` Andy Lutomirski
2017-12-01 21:21       ` Dave Hansen
2017-12-01 21:59         ` Andy Lutomirski
2017-12-02  6:41         ` Kevin Easton
2017-11-27 10:45 ` [PATCH 17/21] x86/entry/64: Return to userspace from the trampoline stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 18/21] x86/entry/64: Create a per-CPU SYSCALL entry trampoline Ingo Molnar
2017-11-27 10:45 ` [PATCH 19/21] x86/entry/64: Move the IST stacks into 'struct cpu_entry_area' Ingo Molnar
2017-11-27 10:45 ` [PATCH 20/21] x86/entry/64: Remove the SYSENTER stack canary Ingo Molnar
2017-11-27 10:45 ` Ingo Molnar [this message]
2017-12-01 17:59   ` [PATCH 21/21] x86/entry: Clean up the SYSENTER_stack code Borislav Petkov

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