From a8599e090f2da35d013f01bbd14330ef9ab0fe69 Mon Sep 17 00:00:00 2001 From: Jilles Tjoelker Date: Wed, 5 Sep 2012 21:41:05 +0000 Subject: libc/i386: Do not export .cerror. For some reason, libc exports the symbol .cerror (HIDENAME(cerror)), albeit in the FBSDprivate_1.0 version. It looks like there is no reason for this since it is not used from other libraries. Given that it cannot be accessed from C and its strange calling convention, it is rather unlikely that other things rely on it. Perhaps it is from a time when symbols could not be hidden. Not exporting .cerror causes it to be jumped to directly instead of via the PLT. This change also takes advantage of .cerror's new status by not saving and loading %ebx before jumping to it. (Therefore, .cerror now saves and loads %ebx itself.) Where there was a conditional jump to a jump to .cerror, the conditional jump has been changed to jump to .cerror directly (many modern CPUs don't do static prediction and in any case it is not much of a benefit anyway). This change makes libc.so.7 a few kilobytes smaller. Reviewed by: kib --- lib/libc/i386/SYS.h | 12 ++++++------ lib/libc/i386/Symbol.map | 1 - lib/libc/i386/gen/rfork_thread.S | 3 +-- lib/libc/i386/sys/Ovfork.S | 3 +-- lib/libc/i386/sys/brk.S | 9 ++------- lib/libc/i386/sys/cerror.S | 5 +++-- lib/libc/i386/sys/exect.S | 3 +-- lib/libc/i386/sys/getcontext.S | 5 +---- lib/libc/i386/sys/ptrace.S | 5 +---- lib/libc/i386/sys/sbrk.S | 9 ++------- lib/libc/i386/sys/syscall.S | 5 +---- 11 files changed, 19 insertions(+), 41 deletions(-) diff --git a/lib/libc/i386/SYS.h b/lib/libc/i386/SYS.h index a4a147a91176..355b117e9476 100644 --- a/lib/libc/i386/SYS.h +++ b/lib/libc/i386/SYS.h @@ -36,21 +36,21 @@ #include #include -#define SYSCALL(x) 2: PIC_PROLOGUE; jmp PIC_PLT(HIDENAME(cerror)); \ - ENTRY(__CONCAT(__sys_,x)); \ +#define SYSCALL(x) ENTRY(__CONCAT(__sys_,x)); \ .weak CNAME(x); \ .set CNAME(x),CNAME(__CONCAT(__sys_,x)); \ .weak CNAME(__CONCAT(_,x)); \ .set CNAME(__CONCAT(_,x)),CNAME(__CONCAT(__sys_,x)); \ - mov __CONCAT($SYS_,x),%eax; KERNCALL; jb 2b + mov __CONCAT($SYS_,x),%eax; KERNCALL; \ + jb HIDENAME(cerror) #define RSYSCALL(x) SYSCALL(x); ret; END(__CONCAT(__sys_,x)) -#define PSEUDO(x) 2: PIC_PROLOGUE; jmp PIC_PLT(HIDENAME(cerror)); \ - ENTRY(__CONCAT(__sys_,x)); \ +#define PSEUDO(x) ENTRY(__CONCAT(__sys_,x)); \ .weak CNAME(__CONCAT(_,x)); \ .set CNAME(__CONCAT(_,x)),CNAME(__CONCAT(__sys_,x)); \ - mov __CONCAT($SYS_,x),%eax; KERNCALL; jb 2b; ret; \ + mov __CONCAT($SYS_,x),%eax; KERNCALL; \ + jb HIDENAME(cerror); ret; \ END(__CONCAT(__sys_,x)) /* gas messes up offset -- although we don't currently need it, do for BCS */ diff --git a/lib/libc/i386/Symbol.map b/lib/libc/i386/Symbol.map index 8a0180228a3c..78be4c40bc59 100644 --- a/lib/libc/i386/Symbol.map +++ b/lib/libc/i386/Symbol.map @@ -63,7 +63,6 @@ FBSDprivate_1.0 { __sys_vfork; _vfork; _end; - .cerror; _brk; .curbrk; .minbrk; diff --git a/lib/libc/i386/gen/rfork_thread.S b/lib/libc/i386/gen/rfork_thread.S index 3333d8483761..1f8181d0cfbc 100644 --- a/lib/libc/i386/gen/rfork_thread.S +++ b/lib/libc/i386/gen/rfork_thread.S @@ -113,8 +113,7 @@ ENTRY(rfork_thread) popl %esi movl %ebp, %esp popl %ebp - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) + jmp HIDENAME(cerror) END(rfork_thread) .section .note.GNU-stack,"",%progbits diff --git a/lib/libc/i386/sys/Ovfork.S b/lib/libc/i386/sys/Ovfork.S index e3cc45ddb86d..3ef716976942 100644 --- a/lib/libc/i386/sys/Ovfork.S +++ b/lib/libc/i386/sys/Ovfork.S @@ -50,8 +50,7 @@ ENTRY(__sys_vfork) jmp *%ecx 1: pushl %ecx - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) + jmp HIDENAME(cerror) END(__sys_vfork) .section .note.GNU-stack,"",%progbits diff --git a/lib/libc/i386/sys/brk.S b/lib/libc/i386/sys/brk.S index 968e43744b08..8a465d2a4a59 100644 --- a/lib/libc/i386/sys/brk.S +++ b/lib/libc/i386/sys/brk.S @@ -58,14 +58,11 @@ ENTRY(brk) ok: mov $SYS_break,%eax KERNCALL - jb err + jb HIDENAME(cerror) movl 4(%esp),%eax movl %eax,(%edx) movl $0,%eax ret -err: - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) #else @@ -77,13 +74,11 @@ err: ok: mov $SYS_break,%eax KERNCALL - jb err + jb HIDENAME(cerror) movl 4(%esp),%eax movl %eax,HIDENAME(curbrk) movl $0,%eax ret -err: - jmp HIDENAME(cerror) #endif END(brk) diff --git a/lib/libc/i386/sys/cerror.S b/lib/libc/i386/sys/cerror.S index 129cc1b02f21..ad3a0333a3bb 100644 --- a/lib/libc/i386/sys/cerror.S +++ b/lib/libc/i386/sys/cerror.S @@ -48,13 +48,14 @@ __FBSDID("$FreeBSD$"); .globl CNAME(__error) .type CNAME(__error),@function HIDENAME(cerror): - pushl %eax #ifdef PIC - /* The caller must execute the PIC prologue before jumping to cerror. */ + PIC_PROLOGUE + pushl %eax call PIC_PLT(CNAME(__error)) popl %ecx PIC_EPILOGUE #else + pushl %eax call CNAME(__error) popl %ecx #endif diff --git a/lib/libc/i386/sys/exect.S b/lib/libc/i386/sys/exect.S index 3ae87b8fcd0e..1378b4bad15e 100644 --- a/lib/libc/i386/sys/exect.S +++ b/lib/libc/i386/sys/exect.S @@ -47,8 +47,7 @@ ENTRY(exect) pushl %edx popf KERNCALL - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) /* exect(file, argv, env); */ + jmp HIDENAME(cerror) /* exect(file, argv, env); */ END(exect) .section .note.GNU-stack,"",%progbits diff --git a/lib/libc/i386/sys/getcontext.S b/lib/libc/i386/sys/getcontext.S index c24dbdcdb36f..7114689866e8 100644 --- a/lib/libc/i386/sys/getcontext.S +++ b/lib/libc/i386/sys/getcontext.S @@ -42,12 +42,9 @@ ENTRY(__sys_getcontext) movl (%esp),%ecx /* save getcontext return address */ mov $SYS_getcontext,%eax KERNCALL - jb 1f + jb HIDENAME(cerror) addl $4,%esp /* remove stale (setcontext) return address */ jmp *%ecx /* restore return address */ -1: - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) END(__sys_getcontext) .section .note.GNU-stack,"",%progbits diff --git a/lib/libc/i386/sys/ptrace.S b/lib/libc/i386/sys/ptrace.S index 6e5e8856c6ec..e4bdf7cd28ff 100644 --- a/lib/libc/i386/sys/ptrace.S +++ b/lib/libc/i386/sys/ptrace.S @@ -50,11 +50,8 @@ ENTRY(ptrace) #endif mov $SYS_ptrace,%eax KERNCALL - jb err + jb HIDENAME(cerror) ret -err: - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) END(ptrace) .section .note.GNU-stack,"",%progbits diff --git a/lib/libc/i386/sys/sbrk.S b/lib/libc/i386/sys/sbrk.S index 337087adaa3a..99fc2203b00b 100644 --- a/lib/libc/i386/sys/sbrk.S +++ b/lib/libc/i386/sys/sbrk.S @@ -59,7 +59,7 @@ ENTRY(sbrk) addl %eax,4(%esp) mov $SYS_break,%eax KERNCALL - jb err + jb HIDENAME(cerror) PIC_PROLOGUE movl PIC_GOT(HIDENAME(curbrk)),%edx movl (%edx),%eax @@ -67,9 +67,6 @@ ENTRY(sbrk) PIC_EPILOGUE back: ret -err: - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) #else /* !PIC */ @@ -80,13 +77,11 @@ err: addl %eax,4(%esp) mov $SYS_break,%eax KERNCALL - jb err + jb HIDENAME(cerror) movl HIDENAME(curbrk),%eax addl %ecx,HIDENAME(curbrk) back: ret -err: - jmp HIDENAME(cerror) #endif /* PIC */ END(sbrk) diff --git a/lib/libc/i386/sys/syscall.S b/lib/libc/i386/sys/syscall.S index e5d6e234c6f6..8a086310414b 100644 --- a/lib/libc/i386/sys/syscall.S +++ b/lib/libc/i386/sys/syscall.S @@ -45,11 +45,8 @@ ENTRY(syscall) KERNCALL push %ecx /* need to push a word to keep stack frame intact upon return; the word must be the return address. */ - jb 1f + jb HIDENAME(cerror) ret -1: - PIC_PROLOGUE - jmp PIC_PLT(HIDENAME(cerror)) END(syscall) .section .note.GNU-stack,"",%progbits -- cgit v1.2.3