[SeaBIOS] [PATCH] fix calculation of PkgLength

[Hu Tao]

On Sun, Jul 07, 2013 at 05:49:30PM +0300, Michael S. Tsirkin wrote:
> On Wed, Jul 03, 2013 at 05:59:07PM +0800, Hu Tao wrote:
> > Currently the calculation of PkgLength isn't acpi-compliant. This
> > patch fixes it to be acpi-compliant.
> > 
> > Signed-off-by: Hu Tao <hutao at cn.fujitsu.com>
> > ---
> > 
> > When testing memory hotplug patchset, I found the PkgLength calculation
> > will cause windows 2012, Windows 2008 BSOD (but not windows XP). After
> > fixing it, the problem is resolved.
> 
> This issue was only seen with the memory hotplug patches correct?

Not exactly. A slight change in the code, for example, changing the 3rd
parameter of encodeLen from 1 to 2 that seems harmless can also cause
the problem. In general, if (ssdt_ptr - ssdt) isn't equal to length (all
three variables seen in build_ssdt()), the problem occurs.

> 
> 
> >  src/acpi.c | 48 ++++++++++++++++++++++++++++++++++++------------
> >  1 file changed, 36 insertions(+), 12 deletions(-)
> > 
> > diff --git a/src/acpi.c b/src/acpi.c
> > index ce988e0..ae28427 100644
> > --- a/src/acpi.c
> > +++ b/src/acpi.c
> > @@ -216,10 +216,34 @@ static inline char getHex(u32 val) {
> >      return (val <= 9) ? ('0' + val) : ('A' + val - 10);
> >  }
> >  
> > +int getBytes(int length, int included)
> > +{
> > +    int nbyte;
> > +
> > +    if (length < (included ? 64 : 64 - 1)) {
> > +        nbyte = 1;
> > +    } else if (length < (included ? 4096 : 4096 - 2)) {
> > +        nbyte = 2;
> > +    } else if (length < (included ? 1048576 : 1048576 - 3)) {
> > +        nbyte = 3;
> > +    } else {
> > +        nbyte = 4;
> > +    }
> > +
> > +    return nbyte;
> > +}
> > +
> >  // Encode a length in an SSDT.
> > +// PkgLength includes itself, but the bytes(PkgLeadByte + ByteData)
> > +// depends on length of following data. This function calculates the
> > +// bytes, given the @length of following data.
> >  static u8 *
> > -encodeLen(u8 *ssdt_ptr, int length, int bytes)
> > +encodeLen(u8 *ssdt_ptr, int length, int included)
> >  {
> > +    int bytes = getBytes(length, included);
> > +    if (!included)
> > +        length += bytes;
> > +
> >      switch (bytes) {
> >      default:
> >      case 4: ssdt_ptr[3] = ((length >> 20) & 0xff);
> > @@ -265,15 +289,15 @@ build_notify(u8 *ssdt_ptr, const char *name, int skip, int count,
> >      count -= skip;
> >  
> >      *(ssdt_ptr++) = 0x14; // MethodOp
> > -    ssdt_ptr = encodeLen(ssdt_ptr, 2+5+(12*count), 2);
> > +    ssdt_ptr = encodeLen(ssdt_ptr, 4+1+(12*count), 0);
> >      memcpy(ssdt_ptr, name, 4);
> >      ssdt_ptr += 4;
> > -    *(ssdt_ptr++) = 0x02; // MethodOp
> > +    *(ssdt_ptr++) = 0x02; // MethodFlags
> >  
> >      int i;
> >      for (i = skip; count-- > 0; i++) {
> >          *(ssdt_ptr++) = 0xA0; // IfOp
> > -        ssdt_ptr = encodeLen(ssdt_ptr, 11, 1);
> > +        ssdt_ptr = encodeLen(ssdt_ptr, 10, 0);
> >          *(ssdt_ptr++) = 0x93; // LEqualOp
> >          *(ssdt_ptr++) = 0x68; // Arg0Op
> >          *(ssdt_ptr++) = 0x0A; // BytePrefix
> > @@ -311,13 +335,13 @@ build_ssdt(void)
> >  {
> >      int acpi_cpus = MaxCountCPUs > 0xff ? 0xff : MaxCountCPUs;
> >      int length = (sizeof(ssdp_misc_aml)                     // _S3_ / _S4_ / _S5_
> > -                  + (1+3+4)                                 // Scope(_SB_)
> > +                  + (1+2+4)                                 // Scope(_SB_)
> >                    + (acpi_cpus * PROC_SIZEOF)               // procs
> > -                  + (1+2+5+(12*acpi_cpus))                  // NTFY
> > -                  + (6+2+1+(1*acpi_cpus))                   // CPON
> > -                  + (1+3+4)                                 // Scope(PCI0)
> > +                  + (1+1+5+(12*acpi_cpus))                  // NTFY
> > +                  + (6+1+1+(1*acpi_cpus))                   // CPON
> > +                  + (1+2+4)                                 // Scope(PCI0)
> >                    + ((PCI_SLOTS - 1) * PCIHP_SIZEOF)        // slots
> > -                  + (1+2+5+(12*(PCI_SLOTS - 1))));          // PCNT
> > +                  + (1+1+5+(12*(PCI_SLOTS - 1))+1));          // PCNT
> >      u8 *ssdt = malloc_high(length);
> >      if (! ssdt) {
> >          warn_noalloc();
> > @@ -359,7 +383,7 @@ build_ssdt(void)
> >  
> >      // build Scope(_SB_) header
> >      *(ssdt_ptr++) = 0x10; // ScopeOp
> > -    ssdt_ptr = encodeLen(ssdt_ptr, length - (ssdt_ptr - ssdt), 3);
> > +    ssdt_ptr = encodeLen(ssdt_ptr, length - (ssdt_ptr - ssdt), 1);
> >      *(ssdt_ptr++) = '_';
> >      *(ssdt_ptr++) = 'S';
> >      *(ssdt_ptr++) = 'B';
> > @@ -387,14 +411,14 @@ build_ssdt(void)
> >      *(ssdt_ptr++) = 'O';
> >      *(ssdt_ptr++) = 'N';
> >      *(ssdt_ptr++) = 0x12; // PackageOp
> > -    ssdt_ptr = encodeLen(ssdt_ptr, 2+1+(1*acpi_cpus), 2);
> > +    ssdt_ptr = encodeLen(ssdt_ptr, 1+(1*acpi_cpus), 0);
> >      *(ssdt_ptr++) = acpi_cpus;
> >      for (i=0; i<acpi_cpus; i++)
> >          *(ssdt_ptr++) = (apic_id_is_present(i)) ? 0x01 : 0x00;
> >  
> >      // build Scope(PCI0) opcode
> >      *(ssdt_ptr++) = 0x10; // ScopeOp
> > -    ssdt_ptr = encodeLen(ssdt_ptr, length - (ssdt_ptr - ssdt), 3);
> > +    ssdt_ptr = encodeLen(ssdt_ptr, length - (ssdt_ptr - ssdt), 1);
> >      *(ssdt_ptr++) = 'P';
> >      *(ssdt_ptr++) = 'C';
> >      *(ssdt_ptr++) = 'I';
> > -- 
> > 1.8.3.1
> > 
> > 
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