sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

libc: make MINIX assembly code position-independent

Browse source 
While here, simplify ucontext.S

	. makes libc link without the messy DT_TEXTREL warning.

Change-Id: I4656d9068eab5ed2fa1e391242883d5dd9d93644
This commit is contained in:
Antoine Leca 2013-02-01 09:39:47 +00:00 committed by Gerrit Code Review
parent 8e87bd84b4
commit 3a0aa55040
2 changed files with 47 additions and 78 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
lib/libc/arch/i386/sys-minix/__sigreturn.S
View file

@ -6,4 +6,10 @@
IMPORT(_sigreturn) IMPORT(_sigreturn)
ENTRY(__sigreturn) ENTRY(__sigreturn)
addl $16, %esp addl $16, %esp
#ifndef PIC
jmp _C_LABEL(_sigreturn) jmp _C_LABEL(_sigreturn)
#else
PIC_PROLOGUE /* push %ebx, but we do not care */
pop %eax /* special knowledge of how PIC works: discard pushed EBX */
jmp PIC_PLT(_C_LABEL(_sigreturn))
#endif /* PIC */

119
lib/libc/arch/i386/sys-minix/ucontext.S
View file

@ -1,26 +1,11 @@
#include <machine/asm.h> #include <machine/asm.h>
#include <ucontextoffsets.h> #include <ucontextoffsets.h>
#ifdef __ACK__
.text
begtext:
#ifdef __ACK__
.rom
#else
.data
#endif
begrom:
.data
begdata:
.bss
begbss:
#endif
IMPORT(getuctx) IMPORT(getuctx)
IMPORT(setuctx) IMPORT(setuctx)
IMPORT(resumecontext) IMPORT(resumecontext)
.globl _C_LABEL(__errno)
/* MCF_MAGIC value from <mcontext.h> */ /* MCF_MAGIC value from <mcontext.h> */
#define MCF_MAGIC 0xc0ffee #define MCF_MAGIC 0xc0ffee
@ -43,59 +28,41 @@ ENTRY(getcontext)
* saving its signal mask, then we can skip the context switch to * saving its signal mask, then we can skip the context switch to
* PM and kernel altogether and only save general-purpose registers. */ * PM and kernel altogether and only save general-purpose registers. */
mov (%esp), %ecx /* Save return address:
* When setcontext or swapcontext is called,
* we jump to this address and continue
* running. */
mov 4(%esp), %edx /* edx = ucp */ mov 4(%esp), %edx /* edx = ucp */
/* Check null pointer */ /* Check null pointer */
cmp $0, %edx /* edx == NULL? */ cmp $0, %edx /* edx == NULL? */
jne 3f /* Not null, continue */ jne 3f /* Not null, continue */
movl $EFAULT, (_C_LABEL(errno)) PIC_PROLOGUE
call PIC_PLT(_C_LABEL(__errno))
PIC_EPILOGUE
movl $EFAULT, (%eax)
xor %eax, %eax xor %eax, %eax
dec %eax /* return -1 */ dec %eax /* return -1 */
ret ret
3: /* Check flags */ 3: /* Check flags */
push %ecx /* save ecx */ mov UC_FLAGS(%edx), %eax /* eax = ucp->uc_flags */
push %ebx /* save ebx */ xor $[UCF_IGNFPU|UCF_IGNSIGM], %eax /* toggle both flags */
lea UC_FLAGS(%edx), %ebx /* ebx = &(ucp->uc_flags) */ jz 5f /* Both were set, skip getuctx */
mov (%ebx), %ecx /* ecx = ucp->uc_flags */ PIC_PROLOGUE
mov $UCF_IGNFPU, %eax
or $UCF_IGNSIGM, %eax
cmp %eax, %ecx /* is UCF_IGNFPU or UCF_IGNSIGM set? */
pop %ebx /* restore ebx */
pop %ecx /* restore ecx */
jz 1f /* Both are set, skip getuctx */
0:
push %ecx /* Save ecx */
push %edx push %edx
call _C_LABEL(getuctx) /* getuctx(ucp) */ call PIC_PLT(_C_LABEL(getuctx)) /* getuctx(ucp) */
pop %edx /* clean up stack and restore edx */ pop %edx /* clean up stack and restore edx */
pop %ecx /* Restore ecx */ PIC_EPILOGUE
1: 5:
/* Save the context */ /* Save the context */
mov 4(%esp), %edx /* edx = ucp */ pop PC(%edx) /* Save real RTA in mcp struct */
pop %eax /* retaddr */
mov %eax, PC(%edx) /* Save real RTA in mcp struct */
mov %esp, SP(%edx) /* Save stack pointer (now pointing to ucp) */ mov %esp, SP(%edx) /* Save stack pointer (now pointing to ucp) */
/* Save GP registers */ /* Save GP registers (except EAX and EDX) */
mov %ebp, BP(%edx) /* Save EBP */ mov %ebp, BP(%edx) /* Save EBP */
mov %esi, SI(%edx) /* Save ESI */ mov %esi, SI(%edx) /* Save ESI */
mov %edi, DI(%edx) /* Save EDI */ mov %edi, DI(%edx) /* Save EDI */
mov %ebx, BX(%edx) /* Save EBX */ mov %ebx, BX(%edx) /* Save EBX */
mov %ecx, CX(%edx) /* Save ECX */ mov %ecx, CX(%edx) /* Save ECX */
movl $MCF_MAGIC, MAGIC(%edx) /* Set magic value */ movl $MCF_MAGIC, MAGIC(%edx) /* Set magic value */
push %eax /* Restore retaddr */
xor %eax, %eax /* Return 0 */ xor %eax, %eax /* Return 0 */
jmp *PC(%edx) /* Return return address */
2:
add $4, %esp /* Remove stale (setcontext) RTA */
jmp *%ecx /* Restore return address */
/* int setcontext(const ucontext_t *ucp) /* int setcontext(const ucontext_t *ucp)
@ -115,52 +82,43 @@ ENTRY(setcontext)
/* Check null pointer */ /* Check null pointer */
cmp $0, %edx /* edx == NULL? */ cmp $0, %edx /* edx == NULL? */
jnz 3f /* Not null, continue */ jnz 3f /* Not null, continue */
movl $EFAULT, (_C_LABEL(errno)) movl $EFAULT, %edx
0: push %edx /* preserve errno */
PIC_PROLOGUE
call PIC_PLT(_C_LABEL(__errno))
PIC_EPILOGUE
pop %edx
movl %edx, (%eax)
xor %eax, %eax xor %eax, %eax
dec %eax /* return -1 */ dec %eax /* return -1 */
ret ret
3: /* Check flags */ 3: /* Check flags */
push %ebx /* save ebx */ cmpl $MCF_MAGIC, MAGIC(%edx) /* is the magic value set (is context valid)?*/
lea MAGIC(%edx), %ebx /* ebx = &(ucp->mc_context.mc_magic) */
mov (%ebx), %ecx /* ecx = ucp->mc_context.mc_magic */
pop %ebx /* restore ebx */
cmp $MCF_MAGIC, %ecx /* is the magic value set (is context valid)?*/
jz 4f /* is set, proceed */ jz 4f /* is set, proceed */
movl $EINVAL, (_C_LABEL(errno)) /* not set, return error code */ movl $EINVAL, %edx /* not set, return error code */
xor %eax, %eax jmp 0b
dec %eax /* return -1 */
ret
4: push %ebx /* save ebx */ 4: mov UC_FLAGS(%edx), %eax /* eax = ucp->uc_flags */
lea UC_FLAGS(%edx), %ebx /* ebx = &(ucp->uc_flags) */ xor $[UCF_IGNFPU|UCF_IGNSIGM], %eax /* toggle both flags */
mov (%ebx), %ecx /* ecx = ucp->uc_flags */ jz 5f /* Both are set, so don't bother restoring FPU
pop %ebx /* restore ebx */
mov $UCF_IGNFPU, %eax
or $UCF_IGNSIGM, %eax
cmp %eax, %ecx /* Are UCF_IGNFPU and UCF_IGNSIGM flags set? */
jz 1f /* Both are set, so don't bother restoring FPU
* state and signal mask */ * state and signal mask */
0: push %ecx /* Save ecx */ PIC_PROLOGUE
push %edx push %edx
call _C_LABEL(setuctx) /* setuctx(ucp) */ call PIC_PLT(_C_LABEL(setuctx)) /* setuctx(ucp) */
pop %edx /* Clean up stack and restore edx */ pop %edx /* Clean up stack and restore edx */
pop %ecx /* Restore ecx */ PIC_EPILOGUE
1: /* Restore the registers */ 5: /* Restore the registers (except EAX and EDX) */
mov 4(%esp), %edx /* edx = ucp */
mov CX(%edx), %ecx /* Restore ECX */ mov CX(%edx), %ecx /* Restore ECX */
mov BX(%edx), %ebx /* Restore EBX */ mov BX(%edx), %ebx /* Restore EBX */
mov DI(%edx), %edi /* Restore EDI */ mov DI(%edx), %edi /* Restore EDI */
mov SI(%edx), %esi /* Restore ESI */ mov SI(%edx), %esi /* Restore ESI */
mov BP(%edx), %ebp /* Restore EBP */ mov BP(%edx), %ebp /* Restore EBP */
mov SP(%edx), %esp /* Restore stack pointer */ mov SP(%edx), %esp /* Restore stack pointer */
jmp *PC(%edx) /* Return to RTA */
2:
jmp *PC(%edx) /* Push RTA onto stack so we can return to it */
/* void ctx_start((void *func)(int arg1, ..., argn), arg1, ..., argn, /* void ctx_start((void *func)(int arg1, ..., argn), arg1, ..., argn,
* ucontext_t *ucp) * ucontext_t *ucp)
@ -168,7 +126,11 @@ ENTRY(setcontext)
* to ucp on the stack. By setting ESP to ESI, we effectively 'remove' all * to ucp on the stack. By setting ESP to ESI, we effectively 'remove' all
* arguments to `func' from the stack. Finally, a call to resumecontext * arguments to `func' from the stack. Finally, a call to resumecontext
* will start the next context in the linked list (or exit the program if * will start the next context in the linked list (or exit the program if
* there is no context). */ * there is no context).
*
* Since PIC needs the EBX register, which is pushed on the stack by
* PIC_PROLOGUE, we need an extra of salsa here.
*/
ENTRY(ctx_start) ENTRY(ctx_start)
/* 0(esp) -> func /* 0(esp) -> func
* 4(esp) -> arg1 * 4(esp) -> arg1
@ -178,9 +140,10 @@ ENTRY(ctx_start)
pop %eax /* eax = func */ pop %eax /* eax = func */
call *%eax /* func(arg1, ..., argn) */ call *%eax /* func(arg1, ..., argn) */
mov %esi, %esp /* Clean up stack */ PIC_PROLOGUE /* may push %ebx, but we do not care */
mov %esi, %esp /* Clean up stack, keep %ebx = &GOT */
/* ucp is now at the top of the stack again */ /* ucp is now at the top of the stack again */
call _C_LABEL(resumecontext) /* resumecontext(ucp) */ call PIC_PLT(_C_LABEL(resumecontext)) /* resumecontext(ucp) */
ret /* never reached */ ret /* never reached */