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ARM: 7442/1: Revert "remove unused restart trampoline"

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This reverts commit fa18484d09.

We need the restart trampoline back so that we can revert a related
problematic patch 6b5c8045ec ("arm: new
way of handling ERESTART_RESTARTBLOCK").

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon 2012-07-04 18:16:30 +01:00 committed by Russell King
parent 82401bf105
commit 3b0c062267
3 changed files with 17 additions and 0 deletions
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13
arch/arm/kernel/signal.c
View File

@ -27,6 +27,7 @@
*/
#define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
#define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
#define SWI_SYS_RESTART (0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE)
/*
* With EABI, the syscall number has to be loaded into r7.
@ -46,6 +47,18 @@ const unsigned long sigreturn_codes[7] = {
MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
};
/*
* Either we support OABI only, or we have EABI with the OABI
* compat layer enabled. In the later case we don't know if
* user space is EABI or not, and if not we must not clobber r7.
* Always using the OABI syscall solves that issue and works for
* all those cases.
*/
const unsigned long syscall_restart_code[2] = {
SWI_SYS_RESTART, /* swi __NR_restart_syscall */
0xe49df004, /* ldr pc, [sp], #4 */
};
/*
* atomically swap in the new signal mask, and wait for a signal.
*/

2
arch/arm/kernel/signal.h
View File

@ -8,5 +8,7 @@
* published by the Free Software Foundation.
*/
#define KERN_SIGRETURN_CODE (CONFIG_VECTORS_BASE + 0x00000500)
#define KERN_RESTART_CODE (KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
extern const unsigned long sigreturn_codes[7];
extern const unsigned long syscall_restart_code[2];

2
arch/arm/kernel/traps.c
View File

@ -820,6 +820,8 @@ void __init early_trap_init(void *vectors_base)
*/
memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
sigreturn_codes, sizeof(sigreturn_codes));
memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
syscall_restart_code, sizeof(syscall_restart_code));
flush_icache_range(vectors, vectors + PAGE_SIZE);
modify_domain(DOMAIN_USER, DOMAIN_CLIENT);