Add unwinding annotations so that unwinding from this function works properly.
Signed-off-by: Stephen Boyd sboyd@codeaurora.org ---
On 08/26, Russell King - ARM Linux wrote:
Looking at the oops dumps you have, it's really quite annoying that they do not contain a proper backtrace. I also have to ask why your logs seem to screw up on the PC/LR values in the oops dumps - they seem to be completely missing.
This fixes the stacktrace for me so that it's actually readable.
CPU: 1 PID: 1 Comm: init Not tainted 4.2.0-rc8-next-20150825-00012-g7b30062de23c-dirty #170 Hardware name: Qualcomm (Flattened Device Tree) task: ee0a8000 ti: ee0b0000 task.ti: ee0b0000 PC is at __clear_user_std+0x16/0x78 LR is at padzero+0x47/0x54 pc : [<c03df522>] lr : [<c02f103b>] psr: 60000033 sp : ee0b1ea8 ip : 00000002 fp : 00000000 r10: 001de22e r9 : 00000000 r8 : ee122300 r7 : ee0b1eb8 r6 : ed8d0300 r5 : 00000000 r4 : 00000051 r3 : 00000055 r2 : 00000000 r1 : 00000dd2 r0 : 001de22e Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment none Control: 50c5787d Table: 2d8d806a DAC: 00000051 Process init (pid: 1, stack limit = 0xee0b0210) Stack: (0xee0b1ea8 to 0xee0b2000) 1ea0: 00000dd2 c02f103b ee124200 c02f175b 00001812 000001cd 1ec0: 001e2a20 00000000 ee122300 00000000 00000000 001e2a20 001de22e 00000001 1ee0: 00000000 00008000 00008000 001dd870 001de22e 001d5870 00000051 00000055 1f00: 00000000 ee0b1eb8 beffffde ed8d0300 ef7f7160 c02c1cfb 00000001 c0865324 1f20: ed8d0300 c0862ca4 fffffff8 00000001 c0852fe0 ed8d0300 00000000 c02c1e7f 1f40: ee0a8000 ee033000 ee126000 ee0b1f58 00000001 c02c2f1f 00000001 ed8d6038 1f60: 00000000 ee0a8280 c0851118 00000000 c0852f50 00000000 00000000 00000000 1f80: 00000000 00000000 00000000 c02c3039 00000000 c02094f5 00000000 c08da000 1fa0: c059f2b5 c059f2d7 00000000 c020e4d5 00000000 00000000 00000000 00000000 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000 [<c03df522>] (__clear_user_std) from [<c02f103b>] (padzero+0x47/0x54) [<c02f103b>] (padzero) from [<c02f175b>] (load_elf_binary+0x573/0xe74) [<c02f175b>] (load_elf_binary) from [<c02c1e7f>] (search_binary_handler+0x4f/0x124) [<c02c1e7f>] (search_binary_handler) from [<c02c2f1f>] (do_execveat_common+0x3df/0x4e0) [<c02c2f1f>] (do_execveat_common) from [<c02c3039>] (do_execve+0x19/0x1c) [<c02c3039>] (do_execve) from [<c059f2d7>] (kernel_init+0x23/0x9c) [<c059f2d7>] (kernel_init) from [<c020e4d5>] (ret_from_fork+0x11/0x3c) Code: 0c03 d011 f1bc 0f02 (f880) 2000
diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S index 970d6c043774..e936352ccb00 100644 --- a/arch/arm/lib/clear_user.S +++ b/arch/arm/lib/clear_user.S @@ -9,6 +9,7 @@ */ #include <linux/linkage.h> #include <asm/assembler.h> +#include <asm/unwind.h>
.text
@@ -20,6 +21,8 @@ */ ENTRY(__clear_user_std) WEAK(arm_clear_user) +UNWIND(.fnstart) +UNWIND(.save {r1, lr}) stmfd sp!, {r1, lr} mov r2, #0 cmp r1, #4 @@ -44,6 +47,7 @@ WEAK(arm_clear_user) USER( strnebt r2, [r0]) mov r0, #0 ldmfd sp!, {r1, pc} +UNWIND(.fnend) ENDPROC(arm_clear_user) ENDPROC(__clear_user_std)