Commit ed8780e3 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-urgent-2020-10-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fixes from Thomas Gleixner:
 "A couple of x86 fixes which missed rc1 due to my stupidity:

   - Drop lazy TLB mode before switching to the temporary address space
     for text patching.

     text_poke() switches to the temporary mm which clears the lazy mode
     and restores the original mm afterwards. Due to clearing lazy mode
     this might restore a already dead mm if exit_mmap() runs in
     parallel on another CPU.

   - Document the x32 syscall design fail vs. syscall numbers 512-547
     properly.

   - Fix the ORC unwinder to handle the inactive task frame correctly.

     This was unearthed due to the slightly different code generation of
     gcc-10.

   - Use an up to date screen_info for the boot params of kexec instead
     of the possibly stale and invalid version which happened to be
     valid when the kexec kernel was loaded"

* tag 'x86-urgent-2020-10-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/alternative: Don't call text_poke() in lazy TLB mode
  x86/syscalls: Document the fact that syscalls 512-547 are a legacy mistake
  x86/unwind/orc: Fix inactive tasks with stack pointer in %sp on GCC 10 compiled kernels
  hyperv_fb: Update screen_info after removing old framebuffer
  x86/kexec: Use up-to-dated screen_info copy to fill boot params
parents 8c2ab803 abee7c49

arch/x86/entry/syscalls/syscall_64.tbl

+6 −4
Original line number Diff line number Diff line
@@ -364,10 +364,10 @@ 
440	common	process_madvise		sys_process_madvise



#

# x32-specific system call numbers start at 512 to avoid cache impact

# for native 64-bit operation. The __x32_compat_sys stubs are created

# on-the-fly for compat_sys_*() compatibility system calls if X86_X32

# is defined.

# Due to a historical design error, certain syscalls are numbered differently

# in x32 as compared to native x86_64.  These syscalls have numbers 512-547.

# Do not add new syscalls to this range.  Numbers 548 and above are available

# for non-x32 use.

#

512	x32	rt_sigaction		compat_sys_rt_sigaction

513	x32	rt_sigreturn		compat_sys_x32_rt_sigreturn
@@ -405,3 +405,5 @@ 
545	x32	execveat		compat_sys_execveat

546	x32	preadv2			compat_sys_preadv64v2

547	x32	pwritev2		compat_sys_pwritev64v2

# This is the end of the legacy x32 range.  Numbers 548 and above are

# not special and are not to be used for x32-specific syscalls.

arch/x86/kernel/alternative.c

+9 −0
Original line number Diff line number Diff line
@@ -807,6 +807,15 @@ static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm) 
	temp_mm_state_t temp_state;



	lockdep_assert_irqs_disabled();



	/*

	 * Make sure not to be in TLB lazy mode, as otherwise we'll end up

	 * with a stale address space WITHOUT being in lazy mode after

	 * restoring the previous mm.

	 */

	if (this_cpu_read(cpu_tlbstate.is_lazy))

		leave_mm(smp_processor_id());



	temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm);

	switch_mm_irqs_off(NULL, mm, current);

arch/x86/kernel/kexec-bzimage64.c

+1 −2
Original line number Diff line number Diff line
@@ -200,8 +200,7 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params, 
	params->hdr.hardware_subarch = boot_params.hdr.hardware_subarch;



	/* Copying screen_info will do? */

	memcpy(&params->screen_info, &boot_params.screen_info,

				sizeof(struct screen_info));

	memcpy(&params->screen_info, &screen_info, sizeof(struct screen_info));



	/* Fill in memsize later */

	params->screen_info.ext_mem_k = 0;

arch/x86/kernel/unwind_orc.c

+1 −8
Original line number Diff line number Diff line
@@ -321,19 +321,12 @@ EXPORT_SYMBOL_GPL(unwind_get_return_address); 


unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)

{

	struct task_struct *task = state->task;



	if (unwind_done(state))

		return NULL;



	if (state->regs)

		return &state->regs->ip;



	if (task != current && state->sp == task->thread.sp) {

		struct inactive_task_frame *frame = (void *)task->thread.sp;

		return &frame->ret_addr;

	}



	if (state->sp)

		return (unsigned long *)state->sp - 1;
@@ -663,7 +656,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task, 
	} else {

		struct inactive_task_frame *frame = (void *)task->thread.sp;



		state->sp = task->thread.sp;

		state->sp = task->thread.sp + sizeof(*frame);

		state->bp = READ_ONCE_NOCHECK(frame->bp);

		state->ip = READ_ONCE_NOCHECK(frame->ret_addr);

		state->signal = (void *)state->ip == ret_from_fork;

drivers/video/fbdev/hyperv_fb.c

+8 −1
Original line number Diff line number Diff line
@@ -1114,8 +1114,15 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) 
getmem_done:

	remove_conflicting_framebuffers(info->apertures,

					KBUILD_MODNAME, false);

	if (!gen2vm)



	if (gen2vm) {

		/* framebuffer is reallocated, clear screen_info to avoid misuse from kexec */

		screen_info.lfb_size = 0;

		screen_info.lfb_base = 0;

		screen_info.orig_video_isVGA = 0;

	} else {

		pci_dev_put(pdev);

	}

	kfree(info->apertures);



	return 0;

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