From: Andy Lutomirski <luto@kernel.org>
To: X86 ML <x86@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Brian Gerst <brgerst@gmail.com>,
Dave Hansen <dave.hansen@intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v3 01/19] x86/asm/64: Allocate and enable the SYSENTER stack
Date: Thu, 23 Nov 2017 20:32:47 -0800 [thread overview]
Message-ID: <c37d6e68a73e1b5b1203e0e95b488fa8092b3cfb.1511497875.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1511497874.git.luto@kernel.org>
In-Reply-To: <cover.1511497874.git.luto@kernel.org>
This will simplify future changes that want scratch variables early in
the SYSENTER handler -- they'll be able to spill registers to the
stack. It also lets us get rid of a SWAPGS_UNSAFE_STACK user.
This does not depend on CONFIG_IA32_EMULATION because we'll want the
stack space even without IA32 emulation.
As far as I can tell, the reason that this wasn't done from day 1 is
that we use IST for #DB and #BP, which is IMO rather nasty and causes
a lot more problems than it solves. But, since #DB uses IST, we don't
actually need a real stack for SYSENTER (because SYSENTER with TF set
will invoke #DB on the IST stack rather than the SYSENTER stack).
I want to remove IST usage from these vectors some day, and this patch
is a prerequisite for that as well.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/entry_64_compat.S | 2 +-
arch/x86/include/asm/processor.h | 3 ---
arch/x86/kernel/asm-offsets.c | 5 +++++
arch/x86/kernel/asm-offsets_32.c | 5 -----
arch/x86/kernel/cpu/common.c | 4 +++-
arch/x86/kernel/process.c | 2 --
arch/x86/kernel/traps.c | 3 +--
7 files changed, 10 insertions(+), 14 deletions(-)
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 568e130d932c..dcc6987f9bae 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -48,7 +48,7 @@
*/
ENTRY(entry_SYSENTER_compat)
/* Interrupts are off on entry. */
- SWAPGS_UNSAFE_STACK
+ SWAPGS
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
/*
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index cc16fa882e3e..504a3bb4d5f0 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -340,14 +340,11 @@ struct tss_struct {
*/
unsigned long io_bitmap[IO_BITMAP_LONGS + 1];
-#ifdef CONFIG_X86_32
/*
* Space for the temporary SYSENTER stack.
*/
unsigned long SYSENTER_stack_canary;
unsigned long SYSENTER_stack[64];
-#endif
-
} ____cacheline_aligned;
DECLARE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss);
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 8ea78275480d..b275863128eb 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -93,4 +93,9 @@ 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));
}
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index dedf428b20b6..52ce4ea16e53 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -50,11 +50,6 @@ void foo(void)
DEFINE(TSS_sysenter_sp0, offsetof(struct tss_struct, x86_tss.sp0) -
offsetofend(struct tss_struct, SYSENTER_stack));
- /* 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));
-
#ifdef CONFIG_CC_STACKPROTECTOR
BLANK();
OFFSET(stack_canary_offset, stack_canary, canary);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index fa998ca8aa5a..ccb5f66c4e5b 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1386,7 +1386,9 @@ 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, 0ULL);
+ wrmsrl_safe(MSR_IA32_SYSENTER_ESP,
+ (unsigned long)this_cpu_ptr(&cpu_tss) +
+ offsetofend(struct tss_struct, SYSENTER_stack));
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)entry_SYSENTER_compat);
#else
wrmsrl(MSR_CSTAR, (unsigned long)ignore_sysret);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 97fb3e5737f5..35d674157fda 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -71,9 +71,7 @@ __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
*/
.io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 },
#endif
-#ifdef CONFIG_X86_32
.SYSENTER_stack_canary = STACK_END_MAGIC,
-#endif
};
EXPORT_PER_CPU_SYMBOL(cpu_tss);
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b7b0f74a2150..2008dd0f8ccb 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -800,14 +800,13 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
debug_stack_usage_dec();
exit:
-#if defined(CONFIG_X86_32)
/*
* This is the most likely code path that involves non-trivial use
* of the SYSENTER stack. Check that we haven't overrun it.
*/
WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC,
"Overran or corrupted SYSENTER stack\n");
-#endif
+
ist_exit(regs);
}
NOKPROBE_SYMBOL(do_debug);
--
2.13.6
next prev parent reply other threads:[~2017-11-24 4:37 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-24 4:32 [PATCH v3 00/19] Entry stack switching Andy Lutomirski
2017-11-24 4:32 ` Andy Lutomirski [this message]
2017-11-24 4:32 ` [PATCH v3 02/19] x86/dumpstack: Add get_stack_info() support for the SYSENTER stack Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 03/19] x86/gdt: Put per-cpu GDT remaps in ascending order Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 04/19] x86/fixmap: Generalize the GDT fixmap mechanism Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 05/19] x86/kasan/64: Teach KASAN about the cpu_entry_area Andy Lutomirski
2017-11-24 13:16 ` Andrey Ryabinin
2017-11-24 16:27 ` Andy Lutomirski
2017-11-24 17:21 ` [PATCH v4] x86/mm/kasan: " Andrey Ryabinin
2017-11-24 19:26 ` Andy Lutomirski
2017-11-24 17:26 ` [PATCH v3 05/19] x86/kasan/64: " Andrey Ryabinin
2017-11-24 4:32 ` [PATCH v3 06/19] x86/asm: Fix assumptions that the HW TSS is at the beginning of cpu_tss Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 07/19] x86/dumpstack: Handle stack overflow on all stacks Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 08/19] x86/asm: Move SYSENTER_stack to the beginning of struct tss_struct Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 09/19] x86/asm: Remap the TSS into the cpu entry area Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 10/19] x86/asm/64: Separate cpu_current_top_of_stack from TSS.sp0 Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 11/19] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 12/19] x86/asm/64: Use a percpu trampoline stack for IDT entries Andy Lutomirski
2017-11-24 4:32 ` [PATCH v3 13/19] x86/asm/64: Return to userspace from the trampoline stack Andy Lutomirski
2017-11-24 4:33 ` [PATCH v3 14/19] x86/entry/64: Create a percpu SYSCALL entry trampoline Andy Lutomirski
2017-11-24 11:39 ` David Laight
2017-12-01 5:56 ` Andy Lutomirski
2017-11-24 4:33 ` [PATCH v3 15/19] x86/irq: Remove an old outdated comment about context tracking races Andy Lutomirski
2017-11-24 4:33 ` [PATCH v3 16/19] x86/irq/64: In the stack overflow warning, print the offending IP Andy Lutomirski
2017-11-24 4:33 ` [PATCH v3 17/19] x86/entry/64: Move the IST stacks into cpu_entry_area Andy Lutomirski
2017-11-24 4:33 ` [PATCH v3 18/19] x86/entry/64: Remove the SYSENTER stack canary Andy Lutomirski
2017-11-24 4:33 ` [PATCH v3 19/19] x86/entry: Clean up SYSENTER_stack code Andy Lutomirski
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