x86/xen: Use clear_bss() for Xen PV guests

Instead of clearing the bss area in assembly code, use the clear_bss()
function.

This requires to pass the start_info address as parameter to
xen_start_kernel() in order to avoid the xen_start_info being zeroed
again.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20220630071441.28576-2-jgross@suse.com

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f8b9ee9..f37cbff 100644 (file)
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -120,6 +120,9 @@ void *extend_brk(size_t size, size_t align);
        static char __brk_##name[size]
 
 extern void probe_roms(void);
+
+void clear_bss(void);
+
 #ifdef __i386__
 
 asmlinkage void __init i386_start_kernel(void);

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index bd4a341..e7e2332 100644 (file)
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -426,7 +426,7 @@ void __init do_early_exception(struct pt_regs *regs, int trapnr)
 
 /* Don't add a printk in there. printk relies on the PDA which is not initialized 
    yet. */
-static void __init clear_bss(void)
+void __init clear_bss(void)
 {
        memset(__bss_start, 0,
               (unsigned long) __bss_stop - (unsigned long) __bss_start);

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index e3297b1..70fb2ea 100644 (file)
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1183,15 +1183,19 @@ static void __init xen_domu_set_legacy_features(void)
 extern void early_xen_iret_patch(void);
 
 /* First C function to be called on Xen boot */
-asmlinkage __visible void __init xen_start_kernel(void)
+asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
 {
        struct physdev_set_iopl set_iopl;
        unsigned long initrd_start = 0;
        int rc;
 
-       if (!xen_start_info)
+       if (!si)
                return;
 
+       clear_bss();
+
+       xen_start_info = si;
+
        __text_gen_insn(&early_xen_iret_patch,
                        JMP32_INSN_OPCODE, &early_xen_iret_patch, &xen_iret,
                        JMP32_INSN_SIZE);

diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index 3a2cd93..13af6fe 100644 (file)
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -48,15 +48,6 @@ SYM_CODE_START(startup_xen)
        ANNOTATE_NOENDBR
        cld
 
-       /* Clear .bss */
-       xor %eax,%eax
-       mov $__bss_start, %rdi
-       mov $__bss_stop, %rcx
-       sub %rdi, %rcx
-       shr $3, %rcx
-       rep stosq
-
-       mov %rsi, xen_start_info
        mov initial_stack(%rip), %rsp
 
        /* Set up %gs.
@@ -71,6 +62,7 @@ SYM_CODE_START(startup_xen)
        cdq
        wrmsr
 
+       mov     %rsi, %rdi
        call xen_start_kernel
 SYM_CODE_END(startup_xen)
        __FINIT