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authorlinted <linted@users.noreply.github.com>2022-08-20 16:41:38 -0400
committerWaldemar Brodkorb <wbx@openadk.org>2022-09-07 08:32:47 +0200
commit365da5ab379a3e38e196cad370695c4b300cfe51 (patch)
treeaa4eeb3a03c03dcd11570247b328086f2c9208ac /libc/sysdeps
parentd46709504efa46e5b9b52739a48ab61b39fd4971 (diff)
Added support for creation of Static Position-Independent Executables (PIE) on mips
Updated config to allow compilation of rcrt1.o for mips and modified it's crt1.S to perform relocates in __start. The mips architecture performs relocations differently then most other architectures. reloc_static_pie was rewritten, taking code from dl-startup.c, in order to perfrom the additional relocations. Modifications were made to mips' dl-startup.h to allow for the use of contained macros without including _start definition. Signed-off-by: linted <linted@users.noreply.github.com>
Diffstat (limited to 'libc/sysdeps')
-rw-r--r--libc/sysdeps/linux/mips/crt1.S23
1 files changed, 23 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/mips/crt1.S b/libc/sysdeps/linux/mips/crt1.S
index 083615515..7c4db447c 100644
--- a/libc/sysdeps/linux/mips/crt1.S
+++ b/libc/sysdeps/linux/mips/crt1.S
@@ -78,6 +78,10 @@
.weak _init
.weak _fini
#endif
+#ifdef L_rcrt1
+ .type reloc_static_pie,@function
+ .hidden .L0
+#endif
.type main,@function
.type __uClibc_main,@function
.ent __start
@@ -90,6 +94,25 @@ __start:
PTR_LA $28, _gp /* Setup GP correctly if we're non-PIC. */
move $31, $0
#endif
+#ifdef L_rcrt1
+ PTR_LA $4, _DYNAMIC /* Place _DYNAMIC into the GOT */
+ REG_S $4, -0x7ff0($28) /* offset to GOT stolen from dl-startup */
+ jal .L0 /* Get the current $pc address */
+.L0:
+ PTR_SUBU $4, $31, $25 /* Calculate load addr */
+ move $31, $0 /* Clear ra */
+ and $29, -2 * SZREG /* Ensure stack is aligned */
+ PTR_ADDIU $29, (-2 * SZREG) /* Allocate 2 register spaces on stack */
+ REG_S $2, SZREG($29) /* Store atexit in case it exists */
+ PTR_LA $5, reloc_static_pie /* function calls before relocation
+ don't work unless we set $t9 manually */
+ PTR_ADDU $25, $4, $5 /* store reloc_static_pie in $t9 */
+ jalr $25 /* call reloc_static_pie */
+ nop /* delay slot, just in case */
+ REG_L $2, SZREG($29) /* cleanup stack */
+ PTR_ADDIU $29, $29, (2 * SZREG)
+
+#endif
PTR_LA $4, main /* main */
PTR_L $5, 0($29) /* argc */