linux-kernel - [RFC 2/3] x86/coredump: use core regs, rather that TIF

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Message-ID: <1461600763-3534-2-git-send-email-dsafonov@virtuozzo.com>
Date:	Mon, 25 Apr 2016 19:12:42 +0300
From:	Dmitry Safonov <dsafonov@...tuozzo.com>
To:	<linux-kernel@...r.kernel.org>
CC:	<0x7f454c46@...il.com>, Dmitry Safonov <dsafonov@...tuozzo.com>,
	Andy Lutomirski <luto@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Alexander Viro <viro@...iv.linux.org.uk>, <x86@...nel.org>,
	<linux-fsdevel@...r.kernel.org>
Subject: [RFC 2/3] x86/coredump: use core regs, rather that TIF_IA32 flag

As we have here core registers, use them to determine application's
mode and sizes of register set and elf_prstatus.

Cc: Andy Lutomirski <luto@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: x86@...nel.org
Cc: linux-fsdevel@...r.kernel.org
Signed-off-by: Dmitry Safonov <dsafonov@...tuozzo.com>
---
 arch/x86/include/asm/compat.h |  8 ++++----
 fs/binfmt_elf.c               | 18 ++++++++++--------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 5a3b2c119ed0..d0b517fc77ff 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -264,10 +264,10 @@ struct compat_shmid64_ds {
 #ifdef CONFIG_X86_X32_ABI
 typedef struct user_regs_struct compat_elf_gregset_t;
 
-#define PR_REG_SIZE(S) (test_thread_flag(TIF_IA32) ? 68 : 216)
-#define PRSTATUS_SIZE(S) (test_thread_flag(TIF_IA32) ? 144 : 296)
-#define SET_PR_FPVALID(S,V) \
-  do { *(int *) (((void *) &((S)->pr_reg)) + PR_REG_SIZE(0)) = (V); } \
+#define PR_REG_SIZE(S, R) (!user_64bit_mode(R) ? 68 : 216)
+#define PRSTATUS_SIZE(S, R) (!user_64bit_mode(R) ? 144 : 296)
+#define SET_PR_FPVALID(S, V, R) \
+  do { *(int *) (((void *) &((S)->pr_reg)) + PR_REG_SIZE(0, R)) = (V); } \
   while (0)
 
 #define COMPAT_USE_64BIT_TIME \
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 81381cc0dd17..6be281ef34f9 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1621,11 +1621,11 @@ static void do_thread_regset_writeback(struct task_struct *task,
 }
 
 #ifndef PR_REG_SIZE
-#define PR_REG_SIZE(S) sizeof(S)
+#define PR_REG_SIZE(S, R) sizeof(S)
 #endif
 
 #ifndef PRSTATUS_SIZE
-#define PRSTATUS_SIZE(S) sizeof(S)
+#define PRSTATUS_SIZE(S, R) sizeof(S)
 #endif
 
 #ifndef PR_REG_PTR
@@ -1633,12 +1633,13 @@ static void do_thread_regset_writeback(struct task_struct *task,
 #endif
 
 #ifndef SET_PR_FPVALID
-#define SET_PR_FPVALID(S, V) ((S)->pr_fpvalid = (V))
+#define SET_PR_FPVALID(S, V, R) ((S)->pr_fpvalid = (V))
 #endif
 
 static int fill_thread_core_info(struct elf_thread_core_info *t,
 				 const struct user_regset_view *view,
-				 long signr, size_t *total)
+				 long signr, size_t *total,
+				 struct pt_regs *regs __maybe_unused)
 {
 	unsigned int i;
 
@@ -1650,11 +1651,11 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 	 */
 	fill_prstatus(&t->prstatus, t->task, signr);
 	(void) view->regsets[0].get(t->task, &view->regsets[0],
-				    0, PR_REG_SIZE(t->prstatus.pr_reg),
+				    0, PR_REG_SIZE(t->prstatus.pr_reg, regs),
 				    PR_REG_PTR(&t->prstatus), NULL);
 
 	fill_note(&t->notes[0], "CORE", NT_PRSTATUS,
-		  PRSTATUS_SIZE(t->prstatus), &t->prstatus);
+		  PRSTATUS_SIZE(t->prstatus, regs), &t->prstatus);
 	*total += notesize(&t->notes[0]);
 
 	do_thread_regset_writeback(t->task, &view->regsets[0]);
@@ -1684,7 +1685,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 						  regset->core_note_type,
 						  size, data);
 				else {
-					SET_PR_FPVALID(&t->prstatus, 1);
+					SET_PR_FPVALID(&t->prstatus, 1, regs);
 					fill_note(&t->notes[i], "CORE",
 						  NT_PRFPREG, size, data);
 				}
@@ -1770,7 +1771,8 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 	 * Now fill in each thread's information.
 	 */
 	for (t = info->thread; t != NULL; t = t->next)
-		if (!fill_thread_core_info(t, view, siginfo->si_signo, &info->size))
+		if (!fill_thread_core_info(t, view, siginfo->si_signo,
+					&info->size, regs))
 			return 0;
 
 	/*
-- 
2.8.0