[PATCH] ARC: fix CONFIG_HARDENED_USERCOPY

[Vineet Gupta]

Currently enabling this triggers a warning

| usercopy: Kernel memory overwrite attempt detected to kernel text (offset 155633, size 11)!
| usercopy: BUG: failure at mm/usercopy.c:99/usercopy_abort()!
|
|gcc generated __builtin_trap
|Path: /bin/busybox
|CPU: 0 PID: 84 Comm: init Not tainted 5.4.22
|
|[ECR ]: 0x00090005 => gcc generated __builtin_trap
|[EFA ]: 0x9024fcaa
|[BLINK ]: usercopy_abort+0x8a/0x8c
|[ERET ]: memfd_fcntl+0x0/0x470
|[STAT32]: 0x80080802 : IE K
|BTA: 0x901ba38c SP: 0xbe161ecc FP: 0xbf9fe950
|LPS: 0x90677408 LPE: 0x9067740c LPC: 0x00000000
|r00: 0x0000003c r01: 0xbf0ed280 r02: 0x00000000
|r03: 0xbe15fa30 r04: 0x00d2803e r05: 0x00000000
|r06: 0x675d7000 r07: 0x00000000 r08: 0x675d9c00
|r09: 0x00000000 r10: 0x0000035c r11: 0x61206572
|r12: 0x9024fcaa r13: 0x0000000b r14: 0x0000000b
|r15: 0x00000000 r16: 0x90169ffc r17: 0x90168000
|r18: 0x00000000 r19: 0xbf092010 r20: 0x00000001
|r21: 0x00000011 r22: 0x5ffffff1 r23: 0x90169ff1
|r24: 0xbe196c00 r25: 0xbf0ed280
|
|Stack Trace:
| memfd_fcntl+0x0/0x470
| usercopy_abort+0x8a/0x8c
| __check_object_size+0x10e/0x138
| copy_strings+0x1f4/0x38c
| __do_execve_file+0x352/0x848
| EV_Trap+0xcc/0xd0

Fixes: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/15
Reported-by: Evgeniy Didin <didin@xxxxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
---
 arch/arc/kernel/vmlinux.lds.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
index 33ce59d91461..e2146a8da195 100644
--- a/arch/arc/kernel/vmlinux.lds.S
+++ b/arch/arc/kernel/vmlinux.lds.S
@@ -57,7 +57,6 @@ SECTIONS
 	.init.ramfs : { INIT_RAM_FS }
 
 	. = ALIGN(PAGE_SIZE);
-	_stext = .;
 
 	HEAD_TEXT_SECTION
 	INIT_TEXT_SECTION(L1_CACHE_BYTES)
@@ -83,6 +82,7 @@ SECTIONS
 
 	.text : {
 		_text = .;
+		_stext = .;
 		TEXT_TEXT
 		SCHED_TEXT
 		CPUIDLE_TEXT
-- 
2.25.1