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https://github.com/cirosantilli/linux-kernel-module-cheat.git
synced 2026-01-23 02:05:57 +01:00
52 lines
1.6 KiB
ArmAsm
52 lines
1.6 KiB
ArmAsm
#include <lkmc.h>
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.global _start
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_start:
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/* Make all CPUs except CPU0 sleep by default. */
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mrc p15, 0, r0, c0, c0, 5
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ands r0, r0, 3
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bne lkmc_cpu_not_0
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/* Prepare the stack for main, mandatory for C code. */
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ldr sp, =lkmc_stack_top
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/* Enable floating point.
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* Code copied from: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0409h/CHDEGGFF.html
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* Without this, SIMD operations such as vmov raise an exception.
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*/
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mrc p15, 0, r0, c1, c0, 2 /* Read CPACR into r0 */
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orr r0, r0, 3 << 20 /* OR in User and Privileged access for CP10 */
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orr r0, r0, 3 << 22 /* OR in User and Privileged access for CP11 */
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bic r0, r0, 3 << 30 /* Clear ASEDIS/D32DIS if set */
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mcr p15, 0, r0, c1, c0, 2 /* Store new access permissions into CPACR */
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isb /* Ensure side-effect of CPACR is visible */
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mov r0, 1 << 30 /* Create value with FPEXC (bit 30) set in r0 */
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vmsr fpexc, r0 /* Enable VFP and SIMD extensions */
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/* https://cirosantilli.com/linux-kernel-module-cheat#magic-failure-string */
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ldr r0, =lkmc_baremetal_on_exit_callback
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bl on_exit
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/* Run main. */
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mov r0, 0
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#if 0
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/* Just turn CLI args off for now since not supported.
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* https://cirosantilli.com/linux-kernel-module-cheat#gem5-baremetal-arm-cli-args */
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ldr r0, =lkmc_argc
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ldr r0, [r0]
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ldr r1, =lkmc_argv
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#else
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/* Run main. */
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mov r0, 0
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#endif
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bl main
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/* If main returns, exit. */
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bl exit
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/* Default action for CPUs besides the first one: sleep forever. */
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LKMC_WEAK(lkmc_cpu_not_0)
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wfe
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b lkmc_cpu_not_0
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