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Tim Deegan

2010-Jul-06 15:35 UTC

[Xen-devel] [PATCH] rombios: move the stack to 0x9e000 and protect it with an e820 entry

rombios: move the stack to 0x9e000 and protect it with an e820 entry
so that we don''t corrupt E820_RAM memory with stack ops in S3 wakeup.
It has to move up so the lowest contiguous RAM area is >= 512MiB.

This relies on the previous fix to let DS != SS

Signed-off-by: Paul Durrant <Paul.Durrant@citrix.com>
Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>

diff -r 4160103f98e3 tools/firmware/hvmloader/hvmloader.c
--- a/tools/firmware/hvmloader/hvmloader.c	Tue Jul 06 16:27:22 2010 +0100
+++ b/tools/firmware/hvmloader/hvmloader.c	Tue Jul 06 16:28:09 2010 +0100
@@ -576,16 +576,64 @@
     printf("vm86 TSS at %08lx\n", virt_to_phys(tss));
 }
 
+static void dump_e820_table(void)
+{
+    struct e820entry *e820 = E820;
+    unsigned int nr = *E820_NR;
+    unsigned int last_end = 0;
+    int i;
+
+    printf("E820 table:\n");
+
+    for (i = 0; i < nr; i++) {
+        unsigned int start = e820[i].addr;
+        unsigned int end = e820[i].addr + e820[i].size;
+
+        if (start < last_end)
+            printf(" OVERLAP!!\n");
+        else if (start > last_end)
+            printf(" HOLE: %08x - %08x\n", last_end, start);
+
+        printf(" [%02d]: %08x - %08x: ", i, start, end);
+        switch (e820[i].type) {
+        case E820_RAM:
+            printf("RAM\n");
+            break;
+        case E820_RESERVED:
+            printf("RESERVED\n");
+            break;
+        case E820_ACPI:
+            printf("ACPI\n");
+            break;
+        case E820_NVS:
+            printf("NVS\n");
+            break;
+        default:
+            printf("UNKNOWN (%08x)\n", e820[i].type);
+            break;
+        }
+
+        last_end = end;
+    }
+}
+
 /* Create an E820 table based on memory parameters provided in hvm_info. */
 static void build_e820_table(void)
 {
     struct e820entry *e820 = E820;
     unsigned int nr = 0;
 
-    /* 0x0-0x9FC00: Ordinary RAM. */
-    e820[nr].addr = 0x0;
-    e820[nr].size = 0x9FC00;
+    /* 0x0-0x9EC00: Ordinary RAM. */
+    /* (Must be at least 512K to keep Windows happy) */
+    e820[nr].addr = 0x00000;
+    e820[nr].size = 0x9E000;
     e820[nr].type = E820_RAM;
+    nr++;
+
+    /* 0x9E000-0x9FC00: Reserved for internal use. */
+    e820[nr].addr = 0x9E000;
+    e820[nr].size = 0x01C00;
+    e820[nr].type = E820_RESERVED;
     nr++;
 
     /* 0x9FC00-0xA0000: Extended BIOS Data Area (EBDA). */
@@ -739,6 +787,7 @@
                ROMBIOS_PHYSICAL_ADDRESS + rombios_sz - 1);
 
     build_e820_table();
+    dump_e820_table();
 
     bios_info = (struct bios_info *)BIOS_INFO_PHYSICAL_ADDRESS;
     memset(bios_info, 0, sizeof(*bios_info));
diff -r 4160103f98e3 tools/firmware/rombios/rombios.c
--- a/tools/firmware/rombios/rombios.c	Tue Jul 06 16:27:22 2010 +0100
+++ b/tools/firmware/rombios/rombios.c	Tue Jul 06 16:28:09 2010 +0100
@@ -1,6 +1,6 @@
 /////////////////////////////////////////////////////////////////////////
 // $Id: rombios.c,v 1.221 2008/12/07 17:32:29 sshwarts Exp $
-/////////////////////////////////////////////////////////////////////////
+////////////////////////////#/////////////////////////////////////////////
 //
 //  Copyright (C) 2002  MandrakeSoft S.A.
 //
@@ -8871,13 +8871,14 @@
 int18_handler: ;; Boot Failure recovery: try the next device.
 
   ;; Reset SP and SS
-  mov  ax, #0xfffe
+  mov  ax, #0x0ffe
   mov  sp, ax
-  xor  ax, ax
+  mov  ax, #0x9e00
   mov  ss, ax
 
   ;; The first time we do this it will have been set to -1 so 
   ;; we will start from device 0.
+  xor  ax, ax
   mov  ds, ax
   mov  bx, word ptr [0x40E]       ;; EBDA segment
   mov  ds, bx                     ;; Set segment
@@ -8911,9 +8912,9 @@
   ;; 
   ;; Reset SP and SS
 
-  mov  ax, #0xfffe
+  mov  ax, #0x0ffe
   mov  sp, ax
-  xor  ax, ax
+  mov  ax, #0x9e00
   mov  ss, ax
 
   call _machine_reset
@@ -10848,10 +10849,9 @@
   ; case 0: normal startup
 
   cli
-  mov  ax, #0xfffe
+  mov  ax, #0x0ffe
   mov  sp, ax
-  xor  ax, ax
-  mov  ds, ax
+  mov  ax, #0x9e00
   mov  ss, ax
 
   ;; Save shutdown status

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Tim Deegan

2010-Jul-06 15:44 UTC

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[Xen-devel] Re: [PATCH] rombios: move the stack to 0x9e000 and protect it with an e820 entry

Ooops - please don''t apply this, it breaks CD-ROM boot. 

Cheers,

Tim.

At 16:35 +0100 on 06 Jul (1278434127), Tim Deegan wrote:> rombios: move the stack to 0x9e000 and protect it with an e820 entry
> so that we don''t corrupt E820_RAM memory with stack ops in S3
wakeup.
> It has to move up so the lowest contiguous RAM area is >= 512MiB.
> 
> This relies on the previous fix to let DS != SS
> 
> Signed-off-by: Paul Durrant <Paul.Durrant@citrix.com>
> Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
> 
> diff -r 4160103f98e3 tools/firmware/hvmloader/hvmloader.c
> --- a/tools/firmware/hvmloader/hvmloader.c	Tue Jul 06 16:27:22 2010 +0100
> +++ b/tools/firmware/hvmloader/hvmloader.c	Tue Jul 06 16:28:09 2010 +0100
> @@ -576,16 +576,64 @@
>      printf("vm86 TSS at %08lx\n", virt_to_phys(tss));
>  }
>  
> +static void dump_e820_table(void)
> +{
> +    struct e820entry *e820 = E820;
> +    unsigned int nr = *E820_NR;
> +    unsigned int last_end = 0;
> +    int i;
> +
> +    printf("E820 table:\n");
> +
> +    for (i = 0; i < nr; i++) {
> +        unsigned int start = e820[i].addr;
> +        unsigned int end = e820[i].addr + e820[i].size;
> +
> +        if (start < last_end)
> +            printf(" OVERLAP!!\n");
> +        else if (start > last_end)
> +            printf(" HOLE: %08x - %08x\n", last_end, start);
> +
> +        printf(" [%02d]: %08x - %08x: ", i, start, end);
> +        switch (e820[i].type) {
> +        case E820_RAM:
> +            printf("RAM\n");
> +            break;
> +        case E820_RESERVED:
> +            printf("RESERVED\n");
> +            break;
> +        case E820_ACPI:
> +            printf("ACPI\n");
> +            break;
> +        case E820_NVS:
> +            printf("NVS\n");
> +            break;
> +        default:
> +            printf("UNKNOWN (%08x)\n", e820[i].type);
> +            break;
> +        }
> +
> +        last_end = end;
> +    }
> +}
> +
>  /* Create an E820 table based on memory parameters provided in hvm_info.
*/
>  static void build_e820_table(void)
>  {
>      struct e820entry *e820 = E820;
>      unsigned int nr = 0;
>  
> -    /* 0x0-0x9FC00: Ordinary RAM. */
> -    e820[nr].addr = 0x0;
> -    e820[nr].size = 0x9FC00;
> +    /* 0x0-0x9EC00: Ordinary RAM. */
> +    /* (Must be at least 512K to keep Windows happy) */
> +    e820[nr].addr = 0x00000;
> +    e820[nr].size = 0x9E000;
>      e820[nr].type = E820_RAM;
> +    nr++;
> +
> +    /* 0x9E000-0x9FC00: Reserved for internal use. */
> +    e820[nr].addr = 0x9E000;
> +    e820[nr].size = 0x01C00;
> +    e820[nr].type = E820_RESERVED;
>      nr++;
>  
>      /* 0x9FC00-0xA0000: Extended BIOS Data Area (EBDA). */
> @@ -739,6 +787,7 @@
>                 ROMBIOS_PHYSICAL_ADDRESS + rombios_sz - 1);
>  
>      build_e820_table();
> +    dump_e820_table();
>  
>      bios_info = (struct bios_info *)BIOS_INFO_PHYSICAL_ADDRESS;
>      memset(bios_info, 0, sizeof(*bios_info));
> diff -r 4160103f98e3 tools/firmware/rombios/rombios.c
> --- a/tools/firmware/rombios/rombios.c	Tue Jul 06 16:27:22 2010 +0100
> +++ b/tools/firmware/rombios/rombios.c	Tue Jul 06 16:28:09 2010 +0100
> @@ -1,6 +1,6 @@
>  /////////////////////////////////////////////////////////////////////////
>  // $Id: rombios.c,v 1.221 2008/12/07 17:32:29 sshwarts Exp $
> -/////////////////////////////////////////////////////////////////////////
> +////////////////////////////#/////////////////////////////////////////////
>  //
>  //  Copyright (C) 2002  MandrakeSoft S.A.
>  //
> @@ -8871,13 +8871,14 @@
>  int18_handler: ;; Boot Failure recovery: try the next device.
>  
>    ;; Reset SP and SS
> -  mov  ax, #0xfffe
> +  mov  ax, #0x0ffe
>    mov  sp, ax
> -  xor  ax, ax
> +  mov  ax, #0x9e00
>    mov  ss, ax
>  
>    ;; The first time we do this it will have been set to -1 so 
>    ;; we will start from device 0.
> +  xor  ax, ax
>    mov  ds, ax
>    mov  bx, word ptr [0x40E]       ;; EBDA segment
>    mov  ds, bx                     ;; Set segment
> @@ -8911,9 +8912,9 @@
>    ;; 
>    ;; Reset SP and SS
>  
> -  mov  ax, #0xfffe
> +  mov  ax, #0x0ffe
>    mov  sp, ax
> -  xor  ax, ax
> +  mov  ax, #0x9e00
>    mov  ss, ax
>  
>    call _machine_reset
> @@ -10848,10 +10849,9 @@
>    ; case 0: normal startup
>  
>    cli
> -  mov  ax, #0xfffe
> +  mov  ax, #0x0ffe
>    mov  sp, ax
> -  xor  ax, ax
> -  mov  ds, ax
> +  mov  ax, #0x9e00
>    mov  ss, ax
>  
>    ;; Save shutdown status
-- 
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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http://lists.xensource.com/xen-devel

Tim Deegan

2010-Jul-07 10:35 UTC

head link

[Xen-devel] Re: [PATCH] rombios: move the stack to 0x9e000 and protect it with an e820 entry

At 16:44 +0100 on 06 Jul (1278434642), Tim Deegan wrote:> Ooops - please don''t apply this, it breaks CD-ROM boot. 
Correction, please do apply it, and also this:

rombios: use explicit SS prefix for calculated on-stack array accesses.
The bcc compiler gets constant array offsets right but does all calculated
array offsets via DS.

Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>

diff -r e316ad18de3c tools/firmware/rombios/rombios.c
--- a/tools/firmware/rombios/rombios.c	Wed Jul 07 11:27:36 2010 +0100
+++ b/tools/firmware/rombios/rombios.c	Wed Jul 07 11:30:14 2010 +0100
@@ -3735,10 +3735,10 @@
   // Validity checks
   if(buffer[0]!=0)return 4;
   for(i=0;i<5;i++){
-    if(buffer[1+i]!=read_byte(0xf000,&isotag[i]))return 5;
+   
if(read_byte(get_SS(),&buffer[1+i])!=read_byte(0xf000,&isotag[i]))return
5;
    }
   for(i=0;i<23;i++)
-    if(buffer[7+i]!=read_byte(0xf000,&eltorito[i]))return 6;
+   
if(read_byte(get_SS(),&buffer[7+i])!=read_byte(0xf000,&eltorito[i]))return
6;
 
   // ok, now we calculate the Boot catalog address
  
lba=buffer[0x4A]*0x1000000+buffer[0x49]*0x10000+buffer[0x48]*0x100+buffer[0x47];

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Xen devel - Jul 2010 - [PATCH] rombios: move the stack to 0x9e000 and protect it with an e820 entry

[Xen-devel] [PATCH] rombios: move the stack to 0x9e000 and protect it with an e820 entry

[Xen-devel] Re: [PATCH] rombios: move the stack to 0x9e000 and protect it with an e820 entry

[Xen-devel] Re: [PATCH] rombios: move the stack to 0x9e000 and protect it with an e820 entry