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authorCatalin Marinas <catalin.marinas@arm.com>2012-10-16 17:07:46 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2012-10-18 20:14:01 +0100
commit16dd46bb781a1d37eeb2377e8e48276e9d14d15d (patch)
treef5f0626fdf4a841ffba5f7ce79e7e8cbfee6a56a /arch
parentf71a1a42667f576ec736bb1200eba2118fee3a22 (diff)
downloadlinux-16dd46bb781a1d37eeb2377e8e48276e9d14d15d.tar.gz
arm64: No need to set the x0-x2 registers in start_thread()
For historical reasons, ARM used to set r0-r2 in start_thread() to the first values on the user stack when starting a new user application. The same logic has been inherited in AArch64. The x0 register is overridden by the sys_execve() return value so it's always zero on success. The x1 and x2 registers are ignored by AArch64 and EABI AArch32 applications, so we can safely remove the register setting for both native and compat user space. This also fixes a potential fault with the kernel accessing user space stack directly. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/processor.h10
1 files changed, 0 insertions, 10 deletions
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 39a208a392f7..5d810044feda 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -92,30 +92,20 @@ static inline void start_thread_common(struct pt_regs *regs, unsigned long pc)
static inline void start_thread(struct pt_regs *regs, unsigned long pc,
unsigned long sp)
{
- unsigned long *stack = (unsigned long *)sp;
-
start_thread_common(regs, pc);
regs->pstate = PSR_MODE_EL0t;
regs->sp = sp;
- regs->regs[2] = stack[2]; /* x2 (envp) */
- regs->regs[1] = stack[1]; /* x1 (argv) */
- regs->regs[0] = stack[0]; /* x0 (argc) */
}
#ifdef CONFIG_COMPAT
static inline void compat_start_thread(struct pt_regs *regs, unsigned long pc,
unsigned long sp)
{
- unsigned int *stack = (unsigned int *)sp;
-
start_thread_common(regs, pc);
regs->pstate = COMPAT_PSR_MODE_USR;
if (pc & 1)
regs->pstate |= COMPAT_PSR_T_BIT;
regs->compat_sp = sp;
- regs->regs[2] = stack[2]; /* x2 (envp) */
- regs->regs[1] = stack[1]; /* x1 (argv) */
- regs->regs[0] = stack[0]; /* x0 (argc) */
}
#endif