The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 78a81d88f60ba773cbe890205e1ee67f00502948
Gitweb: https://git.kernel.org/tip/78a81d88f60ba773cbe890205e1ee67f00502948
Author: Joerg Roedel <jroedel@xxxxxxx>
AuthorDate: Wed, 03 Mar 2021 15:17:12 +01:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Mon, 08 Mar 2021 14:22:17 +01:00
x86/sev-es: Introduce ip_within_syscall_gap() helper
Introduce a helper to check whether an exception came from the syscall
gap and use it in the SEV-ES code. Extend the check to also cover the
compatibility SYSCALL entry path.
Fixes: 315562c9af3d5 ("x86/sev-es: Adjust #VC IST Stack on entering NMI handler")
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 5.10+
Link: https://lkml.kernel.org/r/20210303141716.29223-2-joro@xxxxxxxxxx
---
arch/x86/entry/entry_64_compat.S | 2 ++
arch/x86/include/asm/proto.h | 1 +
arch/x86/include/asm/ptrace.h | 15 +++++++++++++++
arch/x86/kernel/traps.c | 3 +--
4 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 541fdaf..0051cf5 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -210,6 +210,8 @@ SYM_CODE_START(entry_SYSCALL_compat)
/* Switch to the kernel stack */
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
+SYM_INNER_LABEL(entry_SYSCALL_compat_safe_stack, SYM_L_GLOBAL)
+
/* Construct struct pt_regs on stack */
pushq $__USER32_DS /* pt_regs->ss */
pushq %r8 /* pt_regs->sp */
diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h
index 2c35f1c..b6a9d51 100644
--- a/arch/x86/include/asm/proto.h
+++ b/arch/x86/include/asm/proto.h
@@ -25,6 +25,7 @@ void __end_SYSENTER_singlestep_region(void);
void entry_SYSENTER_compat(void);
void __end_entry_SYSENTER_compat(void);
void entry_SYSCALL_compat(void);
+void entry_SYSCALL_compat_safe_stack(void);
void entry_INT80_compat(void);
#ifdef CONFIG_XEN_PV
void xen_entry_INT80_compat(void);
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index d8324a2..409f661 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 +177,19 @@ 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 ip_within_syscall_gap(struct pt_regs *regs)
+{
+ bool ret = (regs->ip >= (unsigned long)entry_SYSCALL_64 &&
+ regs->ip < (unsigned long)entry_SYSCALL_64_safe_stack);
+
+#ifdef CONFIG_IA32_EMULATION
+ ret = ret || (regs->ip >= (unsigned long)entry_SYSCALL_compat &&
+ regs->ip < (unsigned long)entry_SYSCALL_compat_safe_stack);
+#endif
+
+ return ret;
+}
#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 7f5aec7..ac1874a 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 (ip_within_syscall_gap(regs)) {
sp = this_cpu_read(cpu_current_top_of_stack);
goto sync;
}
|