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author | Andy Lutomirski <luto@kernel.org> | 2017-12-04 15:07:12 +0100 |
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committer | Ingo Molnar <mingo@kernel.org> | 2017-12-17 13:59:53 +0100 |
commit | 1a79797b58cddfa948420a7553241c79c013e3ca (patch) | |
tree | 57160262e124ee3c224def88eeb41211d699519f /arch/x86/kernel | |
parent | 4f3789e792296e21405f708cf3cb409d7c7d5683 (diff) | |
download | op-kernel-dev-1a79797b58cddfa948420a7553241c79c013e3ca.zip op-kernel-dev-1a79797b58cddfa948420a7553241c79c013e3ca.tar.gz |
x86/entry/64: Allocate and enable the SYSENTER stack
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=y 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.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.312726423@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r-- | arch/x86/kernel/asm-offsets.c | 5 | ||||
-rw-r--r-- | arch/x86/kernel/asm-offsets_32.c | 5 | ||||
-rw-r--r-- | arch/x86/kernel/cpu/common.c | 4 | ||||
-rw-r--r-- | arch/x86/kernel/process.c | 2 | ||||
-rw-r--r-- | arch/x86/kernel/traps.c | 3 |
5 files changed, 9 insertions, 10 deletions
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 8ea7827..b275863 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 dedf428..52ce4ea1 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 cdf79ab..22f5421 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1361,7 +1361,9 @@ 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 97fb3e5..35d6741 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 d366adf..d3e3bbd 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -794,14 +794,13 @@ 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); |