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Allocate additional space on stack for indirect syscall

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The caller is only required to allocate 16 bytes on the
stack for a0-a3. syscall is handling up to 6 arguments so
additional space is needed on the stack to avoid corrupting the
callers frame.

Change-Id: I054b31696decc3e17d9c70af18cd278b852235d1
This commit is contained in:
Chris Dearman 2013-12-16 14:10:13 -08:00 committed by Elliott Hughes
parent 5e26221a1d
commit 766c7efe28
1 changed files with 8 additions and 0 deletions
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8
libc/arch-mips/bionic/syscall.S
View file

@ -32,6 +32,12 @@
.align 4 .align 4
.ent syscall .ent syscall
/*
* The caller is only required to allocate 16 bytes of stack for a0-a3.
* syscall has up to 6 arguments, so we need space for the extra two arguments.
*/
#define STACKSIZE 2*4
syscall: syscall:
.set noreorder .set noreorder
.cpload $t9 .cpload $t9
@ -42,9 +48,11 @@ syscall:
lw $a3, 16($sp) lw $a3, 16($sp)
lw $t0, 20($sp) lw $t0, 20($sp)
lw $t1, 24($sp) lw $t1, 24($sp)
subu $sp, STACKSIZE
sw $t0, 16($sp) sw $t0, 16($sp)
sw $t1, 20($sp) sw $t1, 20($sp)
syscall syscall
addu $sp, STACKSIZE
bnez $a3, 1f bnez $a3, 1f
move $a0, $v0 move $a0, $v0
j $ra j $ra