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authorDaniel Glöckner <dg@emlix.com>2009-03-04 21:42:27 +0300
committerIngo Molnar <mingo@elte.hu>2009-03-04 22:33:16 +0300
commitab9e18587f4cdb5f3fb3854c732f27a36f98e8f6 (patch)
treeb8d77d5fbdbdf919e4c0134762ff36ef11626802 /arch/x86/math-emu
parentdd39ecf522ba86c70809715af46e6557f6491131 (diff)
downloadlinux-ab9e18587f4cdb5f3fb3854c732f27a36f98e8f6.tar.xz
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/x86/math-emu')
-rw-r--r--arch/x86/math-emu/fpu_aux.c31
1 files changed, 20 insertions, 11 deletions
diff --git a/arch/x86/math-emu/fpu_aux.c b/arch/x86/math-emu/fpu_aux.c
index 491e737ce547..aa0987088774 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);
}
/*