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2dede2d8e9
Patch from Nicolas Pitre The ARM EABI says that the stack pointer has to be 64-bit aligned for reasons already mentioned in patch #3101 when calling C functions. We therefore must verify and adjust sp accordingly when taking an exception from kernel mode since sp might not necessarily be 64-bit aligned if the exception occurs in the middle of a kernel function. If the exception occurs while in user mode then no sp fixup is needed as long as sizeof(struct pt_regs) as well as any additional syscall data stack space remain multiples of 8. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
86 lines
1.6 KiB
ArmAsm
86 lines
1.6 KiB
ArmAsm
#include <linux/config.h>
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/asm-offsets.h>
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#include <asm/errno.h>
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#include <asm/thread_info.h>
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@ Bad Abort numbers
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@ -----------------
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@
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#define BAD_PREFETCH 0
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#define BAD_DATA 1
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#define BAD_ADDREXCPTN 2
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#define BAD_IRQ 3
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#define BAD_UNDEFINSTR 4
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@
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@ Most of the stack format comes from struct pt_regs, but with
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@ the addition of 8 bytes for storing syscall args 5 and 6.
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@ This _must_ remain a multiple of 8 for EABI.
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@
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#define S_OFF 8
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/*
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* The SWI code relies on the fact that R0 is at the bottom of the stack
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* (due to slow/fast restore user regs).
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*/
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#if S_R0 != 0
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#error "Please fix"
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#endif
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.macro zero_fp
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#ifdef CONFIG_FRAME_POINTER
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mov fp, #0
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#endif
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.endm
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#if __LINUX_ARM_ARCH__ >= 6
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.macro disable_irq
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cpsid i
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.endm
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.macro enable_irq
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cpsie i
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.endm
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#else
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.macro disable_irq
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msr cpsr_c, #PSR_I_BIT | SVC_MODE
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.endm
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.macro enable_irq
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msr cpsr_c, #SVC_MODE
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.endm
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#endif
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.macro get_thread_info, rd
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mov \rd, sp, lsr #13
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mov \rd, \rd, lsl #13
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.endm
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.macro alignment_trap, rtemp
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#ifdef CONFIG_ALIGNMENT_TRAP
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ldr \rtemp, .LCcralign
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ldr \rtemp, [\rtemp]
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mcr p15, 0, \rtemp, c1, c0
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#endif
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.endm
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/*
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* These are the registers used in the syscall handler, and allow us to
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* have in theory up to 7 arguments to a function - r0 to r6.
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*
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* r7 is reserved for the system call number for thumb mode.
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*
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* Note that tbl == why is intentional.
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*
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* We must set at least "tsk" and "why" when calling ret_with_reschedule.
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*/
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scno .req r7 @ syscall number
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tbl .req r8 @ syscall table pointer
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why .req r8 @ Linux syscall (!= 0)
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tsk .req r9 @ current thread_info
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