>>> On 17.09.10 at 17:49, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> Ever since c/s 13829, the native (32-bit -> 32-bit) call to invoke the
> secondary kernel has been missing its fourth argument. Apparently
> this worked out because the respective stack location was non-zero.
>
> Starting with Linux 2.6.27 (32-bit) and 2.6.30 (64-bit) a new
> argument is being expected by the secondary kernel, and again
> apparently out of pure luck the 64-bit -> 64-bit case still appears
> to work for those of our customers who want to use it.
>
> The question really is whether this code has ever been tested
> with sufficiently recent kernels in all three variants (32->32, 64->64,
> and 64->32).
>
> While it seems that putting together a patch to address this
> shouldn't be that difficult, a second question is how we can avoid
> getting into the same situation again when Linux extends the
> protocol again.
Below a tentative, untested patch.
Jan
--- 2010-09-20.orig/xen/arch/x86/machine_kexec.c
+++ 2010-09-20/xen/arch/x86/machine_kexec.c
@@ -23,7 +23,11 @@
typedef void (*relocate_new_kernel_t)(
unsigned long indirection_page,
unsigned long *page_list,
- unsigned long start_address);
+ unsigned long start_address,
+#ifdef __i386__
+ unsigned int cpu_has_pae,
+#endif
+ unsigned int preserve_context);
extern int machine_kexec_get_xen(xen_kexec_range_t *range);
@@ -121,7 +125,11 @@ void machine_kexec(xen_kexec_image_t *im
rnk = (relocate_new_kernel_t) image->page_list[1];
(*rnk)(image->indirection_page, image->page_list,
- image->start_address);
+ image->start_address,
+#ifdef __i386__
+ 1 /* cpu_has_pae */,
+#endif
+ 0 /* preserve_context */);
}
}
--- 2010-09-20.orig/xen/arch/x86/x86_64/compat_kexec.S
+++ 2010-09-20/xen/arch/x86/x86_64/compat_kexec.S
@@ -119,6 +119,7 @@ compatibility_mode:
movl %eax, %ss
/* Push arguments onto stack. */
+ pushl $0 /* 20(%esp) - preserve context */
pushl $1 /* 16(%esp) - cpu has pae */
pushl %ecx /* 12(%esp) - start address */
pushl %edx /* 8(%esp) - page list */
--- 2010-09-20.orig/xen/include/asm-x86/cpufeature.h
+++ 2010-09-20/xen/include/asm-x86/cpufeature.h
@@ -139,7 +139,6 @@
#define cpu_has_de boot_cpu_has(X86_FEATURE_DE)
#define cpu_has_pse boot_cpu_has(X86_FEATURE_PSE)
#define cpu_has_tsc boot_cpu_has(X86_FEATURE_TSC)
-#define cpu_has_pae boot_cpu_has(X86_FEATURE_PAE)
#define cpu_has_pge boot_cpu_has(X86_FEATURE_PGE)
#define cpu_has_pat boot_cpu_has(X86_FEATURE_PAT)
#define cpu_has_apic boot_cpu_has(X86_FEATURE_APIC)
@@ -165,7 +164,6 @@
#define cpu_has_de 1
#define cpu_has_pse 1
#define cpu_has_tsc 1
-#define cpu_has_pae 1
#define cpu_has_pge 1
#define cpu_has_pat 1
#define cpu_has_apic boot_cpu_has(X86_FEATURE_APIC)
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