x86: fix i486 suspend to disk CR4 oops

arch/x86/power/cpu_32.c __save_processor_state calls read_cr4()
only a i486 CPU doesn't have the CR4 register.  Trying to read it
produces an invalid opcode oops during suspend to disk.

Use the safe rc4 reading op instead. If the value to be written is
zero the write is skipped.

arch/x86/power/hibernate_asm_32.S
done: swapped the use of %eax and %ecx to use jecxz for
the zero test and jump over store to %cr4.
restore_image: s/%ecx/%eax/ to be consistent with done:

In addition to __save_processor_state, acpi_save_state_mem,
efi_call_phys_prelog, and efi_call_phys_epilog had checks added
(acpi restore was in assembly and already had a check for
non-zero).  There were other reads and writes of CR4, but MCE and
virtualization shouldn't be executed on a i486 anyway.

Signed-off-by: David Fries <david@fries.net>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 81e5ab6542d8e454f315b8c24426e5ec74058756..426e5d91b63a55d9b49d3387e2c40bb56306f104 100644 (file)
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -86,7 +86,7 @@ int acpi_save_state_mem(void)
 #endif /* !CONFIG_64BIT */
 
        header->pmode_cr0 = read_cr0();
-       header->pmode_cr4 = read_cr4();
+       header->pmode_cr4 = read_cr4_safe();
        header->realmode_flags = acpi_realmode_flags;
        header->real_magic = 0x12345678;
 

diff --git a/arch/x86/kernel/efi_32.c b/arch/x86/kernel/efi_32.c
index 4b63c8e1f13b1b078a42dc113403c1952c52f3cc..5cab48ee61a4a6e61e522117d97bbfdabaa95a6d 100644 (file)
--- a/arch/x86/kernel/efi_32.c
+++ b/arch/x86/kernel/efi_32.c
@@ -53,7 +53,7 @@ void efi_call_phys_prelog(void)
         * directory. If I have PAE, I just need to duplicate one entry in
         * page directory.
         */
-       cr4 = read_cr4();
+       cr4 = read_cr4_safe();
 
        if (cr4 & X86_CR4_PAE) {
                efi_bak_pg_dir_pointer[0].pgd =
@@ -91,7 +91,7 @@ void efi_call_phys_epilog(void)
        gdt_descr.size = GDT_SIZE - 1;
        load_gdt(&gdt_descr);
 
-       cr4 = read_cr4();
+       cr4 = read_cr4_safe();
 
        if (cr4 & X86_CR4_PAE) {
                swapper_pg_dir[pgd_index(0)].pgd =

diff --git a/arch/x86/power/cpu_32.c b/arch/x86/power/cpu_32.c
index 7dc5d5cf50a2c85c2cad15c84f5e455abd42a34e..d3e083dea7202c8b5c82e1d7378d947f9f2d42a3 100644 (file)
--- a/arch/x86/power/cpu_32.c
+++ b/arch/x86/power/cpu_32.c
@@ -45,7 +45,7 @@ static void __save_processor_state(struct saved_context *ctxt)
        ctxt->cr0 = read_cr0();
        ctxt->cr2 = read_cr2();
        ctxt->cr3 = read_cr3();
-       ctxt->cr4 = read_cr4();
+       ctxt->cr4 = read_cr4_safe();
 }
 
 /* Needed by apm.c */
@@ -98,7 +98,9 @@ static void __restore_processor_state(struct saved_context *ctxt)
        /*
         * control registers
         */
-       write_cr4(ctxt->cr4);
+       /* cr4 was introduced in the Pentium CPU */
+       if (ctxt->cr4)
+               write_cr4(ctxt->cr4);
        write_cr3(ctxt->cr3);
        write_cr2(ctxt->cr2);
        write_cr0(ctxt->cr0);

diff --git a/arch/x86/power/hibernate_asm_32.S b/arch/x86/power/hibernate_asm_32.S
index b95aa6cfe3cb207befad0a4337678317ec1f9606..4fc7e872c85e4e103039f582eea5050cfc7f2f4a 100644 (file)
--- a/arch/x86/power/hibernate_asm_32.S
+++ b/arch/x86/power/hibernate_asm_32.S
@@ -28,9 +28,9 @@ ENTRY(swsusp_arch_suspend)
        ret
 
 ENTRY(restore_image)
-       movl    resume_pg_dir, %ecx
-       subl    $__PAGE_OFFSET, %ecx
-       movl    %ecx, %cr3
+       movl    resume_pg_dir, %eax
+       subl    $__PAGE_OFFSET, %eax
+       movl    %eax, %cr3
 
        movl    restore_pblist, %edx
        .p2align 4,,7
@@ -52,17 +52,21 @@ copy_loop:
 
 done:
        /* go back to the original page tables */
-       movl    $swapper_pg_dir, %ecx
-       subl    $__PAGE_OFFSET, %ecx
-       movl    %ecx, %cr3
+       movl    $swapper_pg_dir, %eax
+       subl    $__PAGE_OFFSET, %eax
+       movl    %eax, %cr3
        /* Flush TLB, including "global" things (vmalloc) */
-       movl    mmu_cr4_features, %eax
-       movl    %eax, %edx
+       movl    mmu_cr4_features, %ecx
+       jecxz   1f      # cr4 Pentium and higher, skip if zero
+       movl    %ecx, %edx
        andl    $~(1<<7), %edx;  # PGE
        movl    %edx, %cr4;  # turn off PGE
-       movl    %cr3, %ecx;  # flush TLB
-       movl    %ecx, %cr3
-       movl    %eax, %cr4;  # turn PGE back on
+1:
+       movl    %cr3, %eax;  # flush TLB
+       movl    %eax, %cr3
+       jecxz   1f      # cr4 Pentium and higher, skip if zero
+       movl    %ecx, %cr4;  # turn PGE back on
+1:
 
        movl saved_context_esp, %esp
        movl saved_context_ebp, %ebp