Subject: [PATCH 23/25] powerpc: Deliver SEGV signal on pkey violation

From: Ram Pai <[email-masked]>
Date: Fri, 8 Sep 2017 15:45:11 -0700

The value of the pkey, whose protection got violated,
is made available in si_pkey field of the siginfo structure.

Also keep the thread's pkey-register fields up2date.

Signed-off-by: Ram Pai <[email-masked]>
---
 arch/powerpc/kernel/traps.c |   22 ++++++++++++++++++++++
 1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index ec74e20..f2a310d 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -20,6 +20,7 @@
 #include <linux/sched/debug.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
+#include <linux/pkeys.h>
 #include <linux/stddef.h>
 #include <linux/unistd.h>
 #include <linux/ptrace.h>
@@ -265,6 +266,15 @@ void user_single_step_siginfo(struct task_struct *tsk,
 	info->si_addr = (void __user *)regs->nip;
 }
 
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+static void fill_sig_info_pkey(int si_code, siginfo_t *info, unsigned long addr)
+{
+	if (info->si_signo != SIGSEGV || si_code != SEGV_PKUERR)
+		return;
+	info->si_pkey = get_paca()->paca_pkey;
+}
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
 void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
 {
 	siginfo_t info;
@@ -292,6 +302,18 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
 	info.si_signo = signr;
 	info.si_code = code;
 	info.si_addr = (void __user *) addr;
+
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+	/*
+	 * update the thread's pkey related fields.
+	 * core-dump handlers and other sub-systems
+	 * depend on those values.
+	 */
+	thread_pkey_regs_save(&current->thread);
+	/* update the violated-key value */
+	fill_sig_info_pkey(code, &info, addr);
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
 	force_sig_info(signr, &info, current);
 }
 
-- 
1.7.1