michaelh/zephyr
1
0
Fork 0
Code Releases Activity

arm: userspace: Do not overwrite r7 during syscall.

Browse source 
The r7 register is used as a frame pointer on ARM Thumb. As result, it
cannot be modified by the assembly code in functions using stack frame.

This commit replaces r7 by r8, which is a general purpose register.
Also it fixes #7704.

Signed-off-by: Piotr Zięcik <piotr.ziecik@nordicsemi.no>
This commit is contained in:
Piotr Zięcik 2018-06-01 08:49:14 +02:00 • committed by Anas Nashif
commit 997a49ade9
3 changed files with 11 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

4
arch/arm/core/swap_helper.S
View file

@ -365,10 +365,10 @@ _oops:
* r4 - arg5
* r5 - arg6
* r6 - call_id
* r7 - saved link register
* r8 - saved link register
*/
_do_syscall:
ldr r7, [r0, #24] /* grab address of PC from stack frame */
ldr r8, [r0, #24] /* grab address of PC from stack frame */
ldr r1, =_arm_do_syscall
str r1, [r0, #24] /* overwrite the LR to point to _arm_do_syscall */

4
arch/arm/core/userspace.S
View file

@ -120,7 +120,7 @@ SECTION_FUNC(TEXT, _arm_do_syscall)
/*
* r0-r5 contain arguments
* r6 contains call_id
* r7 contains original LR
* r8 contains original LR
*/
ldr ip, =_SYSCALL_BAD
cmp r6, ip
@ -189,6 +189,6 @@ dispatch_syscall:
* return back to original function that called SVC, add 1 to force thumb
* mode
*/
mov ip, r7
mov ip, r8
orrs ip, ip, #1
bx ip

14
include/arch/arm/arch.h
View file

@ -369,7 +369,7 @@ static inline u32_t _arch_syscall_invoke6(u32_t arg1, u32_t arg2, u32_t arg3,
: [svid] "i" (_SVC_CALL_SYSTEM_CALL),
"r" (ret), "r" (r1), "r" (r2), "r" (r3),
"r" (r4), "r" (r5), "r" (r6)
: "r7", "memory");
: "r8", "memory");
return ret;
}
@ -389,7 +389,7 @@ static inline u32_t _arch_syscall_invoke5(u32_t arg1, u32_t arg2, u32_t arg3,
: [svid] "i" (_SVC_CALL_SYSTEM_CALL),
"r" (ret), "r" (r1), "r" (r2), "r" (r3),
"r" (r4), "r" (r6)
: "r7", "memory");
: "r8", "memory");
return ret;
}
@ -408,7 +408,7 @@ static inline u32_t _arch_syscall_invoke4(u32_t arg1, u32_t arg2, u32_t arg3,
: [svid] "i" (_SVC_CALL_SYSTEM_CALL),
"r" (ret), "r" (r1), "r" (r2), "r" (r3),
"r" (r6)
: "r7", "memory");
: "r8", "memory");
return ret;
}
@ -425,7 +425,7 @@ static inline u32_t _arch_syscall_invoke3(u32_t arg1, u32_t arg2, u32_t arg3,
: "=r"(ret)
: [svid] "i" (_SVC_CALL_SYSTEM_CALL),
"r" (ret), "r" (r1), "r" (r2), "r" (r6)
: "r7", "memory", "r3");
: "r8", "memory", "r3");
return ret;
}
@ -440,7 +440,7 @@ static inline u32_t _arch_syscall_invoke2(u32_t arg1, u32_t arg2, u32_t call_id)
: "=r"(ret)
: [svid] "i" (_SVC_CALL_SYSTEM_CALL),
"r" (ret), "r" (r1), "r" (r6)
: "r7", "memory", "r2", "r3");
: "r8", "memory", "r2", "r3");
return ret;
}
@ -454,7 +454,7 @@ static inline u32_t _arch_syscall_invoke1(u32_t arg1, u32_t call_id)
: "=r"(ret)
: [svid] "i" (_SVC_CALL_SYSTEM_CALL),
"r" (ret), "r" (r6)
: "r7", "memory", "r1", "r2", "r3");
: "r8", "memory", "r1", "r2", "r3");
return ret;
}
@ -467,7 +467,7 @@ static inline u32_t _arch_syscall_invoke0(u32_t call_id)
: "=r"(ret)
: [svid] "i" (_SVC_CALL_SYSTEM_CALL),
"r" (ret), "r" (r6)
: "r7", "memory", "r1", "r2", "r3");
: "r8", "memory", "r1", "r2", "r3");
return ret;
}