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Fri, 19 Aug 2016 15:43:53 -0700 From: Daniel Kiper To: xen-devel@lists.xenproject.org Date: Sat, 20 Aug 2016 00:43:14 +0200 Message-Id: <1471646606-28519-5-git-send-email-daniel.kiper@oracle.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1471646606-28519-1-git-send-email-daniel.kiper@oracle.com> References: <1471646606-28519-1-git-send-email-daniel.kiper@oracle.com> X-Source-IP: aserv0021.oracle.com [141.146.126.233] Cc: jgross@suse.com, sstabellini@kernel.org, andrew.cooper3@citrix.com, cardoe@cardoe.com, pgnet.dev@gmail.com, ning.sun@intel.com, david.vrabel@citrix.com, jbeulich@suse.com, qiaowei.ren@intel.com, gang.wei@intel.com, fu.wei@linaro.org Subject: [Xen-devel] [PATCH v5 04/16] x86/boot/reloc: reduce assembly usage as much as possible X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP ..to increase code readability and ease its maintenance. Signed-off-by: Daniel Kiper Reviewed-by: Jan Beulich --- v5 - suggestions/fixes: - improve commit message (suggested by Jan Beulich). --- xen/arch/x86/boot/reloc.c | 52 ++++++++++++++++++++++----------------------- 1 file changed, 25 insertions(+), 27 deletions(-) diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c index 63045c0..9ae42e2 100644 --- a/xen/arch/x86/boot/reloc.c +++ b/xen/arch/x86/boot/reloc.c @@ -15,39 +15,33 @@ asm ( " .text \n" " .globl _start \n" "_start: \n" - " call 1f \n" - "1: pop %ebx \n" - " mov %eax,alloc-1b(%ebx) \n" - " jmp reloc \n" - ); - -/* - * This is our data. Because the code must be relocatable, no BSS is - * allowed. All data is accessed PC-relative with inline assembly. - */ -asm ( - "alloc: \n" - " .long 0 \n" + " push %eax \n" + " push 0x8(%esp) \n" + " call reloc \n" + " ret $0x4 \n" ); typedef unsigned int u32; #include "../../../include/xen/multiboot.h" +#define __stdcall __attribute__((__stdcall__)) + +#define ALIGN_UP(arg, align) \ + (((arg) + (align) - 1) & ~((typeof(arg))(align) - 1)) + +static u32 alloc; + static void *reloc_mbi_struct(void *old, unsigned int bytes) { void *new; - asm( - " call 1f \n" - "1: pop %%edx \n" - " mov alloc-1b(%%edx),%0 \n" - " sub %1,%0 \n" - " and $~15,%0 \n" - " mov %0,alloc-1b(%%edx) \n" - " mov %0,%%edi \n" - " rep movsb \n" - : "=&r" (new), "+c" (bytes), "+S" (old) - : : "edx", "edi", "memory"); - return new; + + alloc -= ALIGN_UP(bytes, 16); + new = (void *)alloc; + + while ( bytes-- ) + *(char *)new++ = *(char *)old++; + + return (void *)alloc; } static char *reloc_mbi_string(char *old) @@ -58,11 +52,15 @@ static char *reloc_mbi_string(char *old) return reloc_mbi_struct(old, p - old + 1); } -multiboot_info_t *reloc(multiboot_info_t *mbi_old) +multiboot_info_t __stdcall *reloc(multiboot_info_t *mbi_old, u32 trampoline) { - multiboot_info_t *mbi = reloc_mbi_struct(mbi_old, sizeof(*mbi)); + multiboot_info_t *mbi; int i; + alloc = trampoline; + + mbi = reloc_mbi_struct(mbi_old, sizeof(*mbi)); + if ( mbi->flags & MBI_CMDLINE ) mbi->cmdline = (u32)reloc_mbi_string((char *)mbi->cmdline);