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authorDaniel Glöckner <dg@emlix.com>2009-03-04 19:42:27 +0100
committerIngo Molnar <mingo@elte.hu>2009-03-04 20:33:16 +0100
commitab9e18587f4cdb5f3fb3854c732f27a36f98e8f6 (patch)
treeb8d77d5fbdbdf919e4c0134762ff36ef11626802 /arch
parentdd39ecf522ba86c70809715af46e6557f6491131 (diff)
x86, math-emu: fix init_fpu for task != current
Impact: fix math-emu related crash while using GDB/ptrace init_fpu() calls finit to initialize a task's xstate, while finit always works on the current task. If we use PTRACE_GETFPREGS on another process and both processes did not already use floating point, we get a null pointer exception in finit. This patch creates a new function finit_task that takes a task_struct parameter. finit becomes a wrapper that simply calls finit_task with current. On the plus side this avoids many calls to get_current which would each resolve to an inline assembler mov instruction. An empty finit_task has been added to i387.h to avoid linker errors in case the compiler still emits the call in init_fpu when CONFIG_MATH_EMULATION is not defined. The declaration of finit in i387.h has been removed as the remaining code using this function gets its prototype from fpu_proto.h. Signed-off-by: Daniel Glöckner <dg@emlix.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: "Pallipadi Venkatesh" <venkatesh.pallipadi@intel.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Bill Metzenthen <billm@melbpc.org.au> LKML-Reference: <E1Lew31-0004il-Fg@mailer.emlix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/i387.h8
-rw-r--r--arch/x86/kernel/i387.c2
-rw-r--r--arch/x86/math-emu/fpu_aux.c31
3 files changed, 28 insertions, 13 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 48f0004db8c..71c9e518398 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -172,7 +172,13 @@ static inline void __save_init_fpu(struct task_struct *tsk)
#else /* CONFIG_X86_32 */
-extern void finit(void);
+#ifdef CONFIG_MATH_EMULATION
+extern void finit_task(struct task_struct *tsk);
+#else
+static inline void finit_task(struct task_struct *tsk)
+{
+}
+#endif
static inline void tolerant_fwait(void)
{
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index b0f61f0dcd0..f2f8540a7f3 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -136,7 +136,7 @@ int init_fpu(struct task_struct *tsk)
#ifdef CONFIG_X86_32
if (!HAVE_HWFP) {
memset(tsk->thread.xstate, 0, xstate_size);
- finit();
+ finit_task(tsk);
set_stopped_child_used_math(tsk);
return 0;
}
diff --git a/arch/x86/math-emu/fpu_aux.c b/arch/x86/math-emu/fpu_aux.c
index 491e737ce54..aa098708877 100644
--- a/arch/x86/math-emu/fpu_aux.c
+++ b/arch/x86/math-emu/fpu_aux.c
@@ -30,20 +30,29 @@ static void fclex(void)
}
/* Needs to be externally visible */
-void finit(void)
+void finit_task(struct task_struct *tsk)
{
- control_word = 0x037f;
- partial_status = 0;
- top = 0; /* We don't keep top in the status word internally. */
- fpu_tag_word = 0xffff;
+ struct i387_soft_struct *soft = &tsk->thread.xstate->soft;
+ struct address *oaddr, *iaddr;
+ soft->cwd = 0x037f;
+ soft->swd = 0;
+ soft->ftop = 0; /* We don't keep top in the status word internally. */
+ soft->twd = 0xffff;
/* The behaviour is different from that detailed in
Section 15.1.6 of the Intel manual */
- operand_address.offset = 0;
- operand_address.selector = 0;
- instruction_address.offset = 0;
- instruction_address.selector = 0;
- instruction_address.opcode = 0;
- no_ip_update = 1;
+ oaddr = (struct address *)&soft->foo;
+ oaddr->offset = 0;
+ oaddr->selector = 0;
+ iaddr = (struct address *)&soft->fip;
+ iaddr->offset = 0;
+ iaddr->selector = 0;
+ iaddr->opcode = 0;
+ soft->no_update = 1;
+}
+
+void finit(void)
+{
+ finit_task(current);
}
/*