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authorImre Deak <imre.deak@nokia.com>2010-04-11 10:58:27 -0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-04-14 06:11:30 -0400
commit82c6f5a5b3e91ef4d2fb8725de4b8cf7affd4d61 (patch)
tree1f077be392f88b7b8355960b882ffbfdc3e6bab6 /arch
parent5c5cac63851f347d8308d69f1892c4af51d7c1a4 (diff)
ARM: 6051/1: VFP: preserve the HW context when calling signal handlers
From: Imre Deak <imre.deak@nokia.com> Signal handlers can use floating point, so prevent them to corrupt the main thread's VFP context. So far there were two signal stack frame formats defined based on the VFP implementation, but the user struct used for ptrace covers all posibilities, so use it for the signal stack too. Introduce also a new user struct for VFP exception registers. In this too fields not relevant to the current VFP architecture are ignored. Support to save / restore the exception registers was added by Will Deacon. Signed-off-by: Imre Deak <imre.deak@nokia.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/ucontext.h23
-rw-r--r--arch/arm/include/asm/user.h12
-rw-r--r--arch/arm/kernel/signal.c93
3 files changed, 111 insertions, 17 deletions
diff --git a/arch/arm/include/asm/ucontext.h b/arch/arm/include/asm/ucontext.h
index bf65e9f4525..47f023aa849 100644
--- a/arch/arm/include/asm/ucontext.h
+++ b/arch/arm/include/asm/ucontext.h
@@ -59,23 +59,22 @@ struct iwmmxt_sigframe {
59#endif /* CONFIG_IWMMXT */ 59#endif /* CONFIG_IWMMXT */
60 60
61#ifdef CONFIG_VFP 61#ifdef CONFIG_VFP
62#if __LINUX_ARM_ARCH__ < 6
63/* For ARM pre-v6, we use fstmiax and fldmiax. This adds one extra
64 * word after the registers, and a word of padding at the end for
65 * alignment. */
66#define VFP_MAGIC 0x56465001 62#define VFP_MAGIC 0x56465001
67#define VFP_STORAGE_SIZE 152
68#else
69#define VFP_MAGIC 0x56465002
70#define VFP_STORAGE_SIZE 144
71#endif
72 63
73struct vfp_sigframe 64struct vfp_sigframe
74{ 65{
75 unsigned long magic; 66 unsigned long magic;
76 unsigned long size; 67 unsigned long size;
77 union vfp_state storage; 68 struct user_vfp ufp;
78}; 69 struct user_vfp_exc ufp_exc;
70} __attribute__((__aligned__(8)));
71
72/*
73 * 8 byte for magic and size, 264 byte for ufp, 12 bytes for ufp_exc,
74 * 4 bytes padding.
75 */
76#define VFP_STORAGE_SIZE sizeof(struct vfp_sigframe)
77
79#endif /* CONFIG_VFP */ 78#endif /* CONFIG_VFP */
80 79
81/* 80/*
@@ -91,7 +90,7 @@ struct aux_sigframe {
91#ifdef CONFIG_IWMMXT 90#ifdef CONFIG_IWMMXT
92 struct iwmmxt_sigframe iwmmxt; 91 struct iwmmxt_sigframe iwmmxt;
93#endif 92#endif
94#if 0 && defined CONFIG_VFP /* Not yet saved. */ 93#ifdef CONFIG_VFP
95 struct vfp_sigframe vfp; 94 struct vfp_sigframe vfp;
96#endif 95#endif
97 /* Something that isn't a valid magic number for any coprocessor. */ 96 /* Something that isn't a valid magic number for any coprocessor. */
diff --git a/arch/arm/include/asm/user.h b/arch/arm/include/asm/user.h
index df95e050f9d..05ac4b06876 100644
--- a/arch/arm/include/asm/user.h
+++ b/arch/arm/include/asm/user.h
@@ -83,11 +83,21 @@ struct user{
83 83
84/* 84/*
85 * User specific VFP registers. If only VFPv2 is present, registers 16 to 31 85 * User specific VFP registers. If only VFPv2 is present, registers 16 to 31
86 * are ignored by the ptrace system call. 86 * are ignored by the ptrace system call and the signal handler.
87 */ 87 */
88struct user_vfp { 88struct user_vfp {
89 unsigned long long fpregs[32]; 89 unsigned long long fpregs[32];
90 unsigned long fpscr; 90 unsigned long fpscr;
91}; 91};
92 92
93/*
94 * VFP exception registers exposed to user space during signal delivery.
95 * Fields not relavant to the current VFP architecture are ignored.
96 */
97struct user_vfp_exc {
98 unsigned long fpexc;
99 unsigned long fpinst;
100 unsigned long fpinst2;
101};
102
93#endif /* _ARM_USER_H */ 103#endif /* _ARM_USER_H */
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index e7714f367eb..907d5a620bc 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -18,6 +18,7 @@
18#include <asm/cacheflush.h> 18#include <asm/cacheflush.h>
19#include <asm/ucontext.h> 19#include <asm/ucontext.h>
20#include <asm/unistd.h> 20#include <asm/unistd.h>
21#include <asm/vfp.h>
21 22
22#include "ptrace.h" 23#include "ptrace.h"
23#include "signal.h" 24#include "signal.h"
@@ -175,6 +176,90 @@ static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
175 176
176#endif 177#endif
177 178
179#ifdef CONFIG_VFP
180
181static int preserve_vfp_context(struct vfp_sigframe __user *frame)
182{
183 struct thread_info *thread = current_thread_info();
184 struct vfp_hard_struct *h = &thread->vfpstate.hard;
185 const unsigned long magic = VFP_MAGIC;
186 const unsigned long size = VFP_STORAGE_SIZE;
187 int err = 0;
188
189 vfp_sync_hwstate(thread);
190 __put_user_error(magic, &frame->magic, err);
191 __put_user_error(size, &frame->size, err);
192
193 /*
194 * Copy the floating point registers. There can be unused
195 * registers see asm/hwcap.h for details.
196 */
197 err |= __copy_to_user(&frame->ufp.fpregs, &h->fpregs,
198 sizeof(h->fpregs));
199 /*
200 * Copy the status and control register.
201 */
202 __put_user_error(h->fpscr, &frame->ufp.fpscr, err);
203
204 /*
205 * Copy the exception registers.
206 */
207 __put_user_error(h->fpexc, &frame->ufp_exc.fpexc, err);
208 __put_user_error(h->fpinst, &frame->ufp_exc.fpinst, err);
209 __put_user_error(h->fpinst2, &frame->ufp_exc.fpinst2, err);
210
211 return err ? -EFAULT : 0;
212}
213
214static int restore_vfp_context(struct vfp_sigframe __user *frame)
215{
216 struct thread_info *thread = current_thread_info();
217 struct vfp_hard_struct *h = &thread->vfpstate.hard;
218 unsigned long magic;
219 unsigned long size;
220 unsigned long fpexc;
221 int err = 0;
222
223 __get_user_error(magic, &frame->magic, err);
224 __get_user_error(size, &frame->size, err);
225
226 if (err)
227 return -EFAULT;
228 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
229 return -EINVAL;
230
231 /*
232 * Copy the floating point registers. There can be unused
233 * registers see asm/hwcap.h for details.
234 */
235 err |= __copy_from_user(&h->fpregs, &frame->ufp.fpregs,
236 sizeof(h->fpregs));
237 /*
238 * Copy the status and control register.
239 */
240 __get_user_error(h->fpscr, &frame->ufp.fpscr, err);
241
242 /*
243 * Sanitise and restore the exception registers.
244 */
245 __get_user_error(fpexc, &frame->ufp_exc.fpexc, err);
246 /* Ensure the VFP is enabled. */
247 fpexc |= FPEXC_EN;
248 /* Ensure FPINST2 is invalid and the exception flag is cleared. */
249 fpexc &= ~(FPEXC_EX | FPEXC_FP2V);
250 h->fpexc = fpexc;
251
252 __get_user_error(h->fpinst, &frame->ufp_exc.fpinst, err);
253 __get_user_error(h->fpinst2, &frame->ufp_exc.fpinst2, err);
254
255 if (!err)
256 vfp_flush_hwstate(thread);
257
258 return err ? -EFAULT : 0;
259}
260
261#endif
262
178/* 263/*
179 * Do a signal return; undo the signal stack. These are aligned to 64-bit. 264 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
180 */ 265 */
@@ -233,8 +318,8 @@ static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
233 err |= restore_iwmmxt_context(&aux->iwmmxt); 318 err |= restore_iwmmxt_context(&aux->iwmmxt);
234#endif 319#endif
235#ifdef CONFIG_VFP 320#ifdef CONFIG_VFP
236// if (err == 0) 321 if (err == 0)
237// err |= vfp_restore_state(&sf->aux.vfp); 322 err |= restore_vfp_context(&aux->vfp);
238#endif 323#endif
239 324
240 return err; 325 return err;
@@ -348,8 +433,8 @@ setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
348 err |= preserve_iwmmxt_context(&aux->iwmmxt); 433 err |= preserve_iwmmxt_context(&aux->iwmmxt);
349#endif 434#endif
350#ifdef CONFIG_VFP 435#ifdef CONFIG_VFP
351// if (err == 0) 436 if (err == 0)
352// err |= vfp_save_state(&sf->aux.vfp); 437 err |= preserve_vfp_context(&aux->vfp);
353#endif 438#endif
354 __put_user_error(0, &aux->end_magic, err); 439 __put_user_error(0, &aux->end_magic, err);
355 440