[PATCH 1/3] x86/sev-es: Introduce from_syscall_gap() helper
From: Joerg Roedel <joro@8bytes.org>
Date: 2021-02-17 12:07:39
Also in:
kvm, lkml, stable
Subsystem:
ptrace support, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Oleg Nesterov, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Joerg Roedel <redacted>
Introduce a helper to check whether an exception came from the syscall
gap and use it in the SEV-ES code
Fixes: 315562c9af3d5 ("x86/sev-es: Adjust #VC IST Stack on entering NMI handler")
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Joerg Roedel <redacted>
---
arch/x86/include/asm/ptrace.h | 8 ++++++++
arch/x86/kernel/traps.c | 3 +--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index d8324a236696..14854b2c4944 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h@@ -94,6 +94,8 @@ struct pt_regs { #include <asm/paravirt_types.h> #endif +#include <asm/proto.h> + struct cpuinfo_x86; struct task_struct;
@@ -175,6 +177,12 @@ static inline bool any_64bit_mode(struct pt_regs *regs) #ifdef CONFIG_X86_64 #define current_user_stack_pointer() current_pt_regs()->sp #define compat_user_stack_pointer() current_pt_regs()->sp + +static inline bool from_syscall_gap(struct pt_regs *regs) +{ + return (regs->ip >= (unsigned long)entry_SYSCALL_64 && + regs->ip < (unsigned long)entry_SYSCALL_64_safe_stack); +} #endif static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 7f5aec758f0e..b4f2b4e9066d 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c@@ -694,8 +694,7 @@ asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *r * In the SYSCALL entry path the RSP value comes from user-space - don't * trust it and switch to the current kernel stack */ - if (regs->ip >= (unsigned long)entry_SYSCALL_64 && - regs->ip < (unsigned long)entry_SYSCALL_64_safe_stack) { + if (from_syscall_gap(regs)) { sp = this_cpu_read(cpu_current_top_of_stack); goto sync; }
--
2.30.0
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