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-rw-r--r--arch/x86/kernel/fpu/signal.c10
-rw-r--r--arch/x86/kernel/fpu/xstate.c13
-rw-r--r--arch/x86/kernel/fpu/xstate.h2
-rw-r--r--arch/x86/kernel/signal.c18
4 files changed, 43 insertions, 0 deletions
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 2b3b9e140dd4..931c5469d7f3 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -64,6 +64,16 @@ setfx:
}
/*
+ * Update the value of PKRU register that was already pushed onto the signal frame.
+ */
+static inline int update_pkru_in_sigframe(struct xregs_state __user *buf, u32 pkru)
+{
+ if (unlikely(!cpu_feature_enabled(X86_FEATURE_OSPKE)))
+ return 0;
+ return __put_user(pkru, (unsigned int __user *)get_xsave_addr_user(buf, XFEATURE_PKRU));
+}
+
+/*
* Signal frame handlers.
*/
static inline bool save_fsave_header(struct task_struct *tsk, void __user *buf)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c5a026fee5e0..fa7628bb541b 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -993,6 +993,19 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
}
EXPORT_SYMBOL_GPL(get_xsave_addr);
+/*
+ * Given an xstate feature nr, calculate where in the xsave buffer the state is.
+ * The xsave buffer should be in standard format, not compacted (e.g. user mode
+ * signal frames).
+ */
+void __user *get_xsave_addr_user(struct xregs_state __user *xsave, int xfeature_nr)
+{
+ if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
+ return NULL;
+
+ return (void __user *)xsave + xstate_offsets[xfeature_nr];
+}
+
#ifdef CONFIG_ARCH_HAS_PKEYS
/*
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index 2ee0b9c53dcc..5f057e50df81 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -54,6 +54,8 @@ extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void
extern void fpu__init_cpu_xstate(void);
extern void fpu__init_system_xstate(unsigned int legacy_size);
+extern void __user *get_xsave_addr_user(struct xregs_state __user *xsave, int xfeature_nr);
+
static inline u64 xfeatures_mask_supervisor(void)
{
return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED;
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 1f1e8e0ac5a3..9dc77ad03a0e 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -61,6 +61,24 @@ static inline int is_x32_frame(struct ksignal *ksig)
}
/*
+ * Enable all pkeys temporarily, so as to ensure that both the current
+ * execution stack as well as the alternate signal stack are writeable.
+ * The application can use any of the available pkeys to protect the
+ * alternate signal stack, and we don't know which one it is, so enable
+ * all. The PKRU register will be reset to init_pkru later in the flow,
+ * in fpu__clear_user_states(), and it is the application's responsibility
+ * to enable the appropriate pkey as the first step in the signal handler
+ * so that the handler does not segfault.
+ */
+static inline u32 sig_prepare_pkru(void)
+{
+ u32 orig_pkru = read_pkru();
+
+ write_pkru(0);
+ return orig_pkru;
+}
+
+/*
* Set up a signal frame.
*/