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sched/x86: Pass kernel thread parameters in 'struct fork_frame'

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Instead of setting up a fake pt_regs context, put the kernel thread
function pointer and arg into the unused callee-restored registers
of 'struct fork_frame'.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471106302-10159-6-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Brian Gerst
2016-08-13 12:38:20 -04:00
committed by Ingo Molnar
parent 0100301bfd
commit 616d24835e
5 changed files with 41 additions and 59 deletions
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arch/x86/kernel/process_64.c
+3 -9
View File
@@ -50,8 +50,6 @@
#include <asm/switch_to.h>
#include <asm/xen/hypervisor.h>
asmlinkage extern void ret_from_fork(void);
__visible DEFINE_PER_CPU(unsigned long, rsp_scratch);
/* Prints also some state that isn't saved in the pt_regs */
@@ -165,15 +163,11 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
if (unlikely(p->flags & PF_KTHREAD)) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->sp = (unsigned long)childregs;
childregs->ss = __KERNEL_DS;
childregs->bx = sp; /* function */
childregs->bp = arg;
childregs->orig_ax = -1;
childregs->cs = __KERNEL_CS | get_kernel_rpl();
childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;
frame->bx = sp; /* function */
frame->r12 = arg;
return 0;
}
frame->bx = 0;
*childregs = *current_pt_regs();
childregs->ax = 0;