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da6a91252a
The trampoline code is used by kretprobes to capture a return from a probed function. This is done by saving the registers, calling the handler, and restoring the registers. The code then returns to the original saved caller return address. It is necessary to do this directly instead of using a software breakpoint because the code used in processing that breakpoint could itself be kprobe'd and cause a problematic reentry into the debug exception handler. Signed-off-by: William Cohen <wcohen@redhat.com> Signed-off-by: David A. Long <dave.long@linaro.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> [catalin.marinas@arm.com: removed unnecessary masking of the PSTATE bits] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
82 lines
1.6 KiB
ArmAsm
82 lines
1.6 KiB
ArmAsm
/*
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* trampoline entry and return code for kretprobes.
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*/
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#include <linux/linkage.h>
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#include <asm/asm-offsets.h>
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#include <asm/assembler.h>
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.text
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.macro save_all_base_regs
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stp x0, x1, [sp, #S_X0]
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stp x2, x3, [sp, #S_X2]
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stp x4, x5, [sp, #S_X4]
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stp x6, x7, [sp, #S_X6]
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stp x8, x9, [sp, #S_X8]
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stp x10, x11, [sp, #S_X10]
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stp x12, x13, [sp, #S_X12]
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stp x14, x15, [sp, #S_X14]
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stp x16, x17, [sp, #S_X16]
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stp x18, x19, [sp, #S_X18]
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stp x20, x21, [sp, #S_X20]
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stp x22, x23, [sp, #S_X22]
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stp x24, x25, [sp, #S_X24]
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stp x26, x27, [sp, #S_X26]
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stp x28, x29, [sp, #S_X28]
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add x0, sp, #S_FRAME_SIZE
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stp lr, x0, [sp, #S_LR]
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/*
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* Construct a useful saved PSTATE
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*/
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mrs x0, nzcv
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mrs x1, daif
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orr x0, x0, x1
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mrs x1, CurrentEL
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orr x0, x0, x1
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mrs x1, SPSel
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orr x0, x0, x1
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stp xzr, x0, [sp, #S_PC]
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.endm
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.macro restore_all_base_regs
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ldr x0, [sp, #S_PSTATE]
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and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT)
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msr nzcv, x0
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ldp x0, x1, [sp, #S_X0]
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ldp x2, x3, [sp, #S_X2]
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ldp x4, x5, [sp, #S_X4]
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ldp x6, x7, [sp, #S_X6]
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ldp x8, x9, [sp, #S_X8]
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ldp x10, x11, [sp, #S_X10]
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ldp x12, x13, [sp, #S_X12]
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ldp x14, x15, [sp, #S_X14]
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ldp x16, x17, [sp, #S_X16]
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ldp x18, x19, [sp, #S_X18]
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ldp x20, x21, [sp, #S_X20]
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ldp x22, x23, [sp, #S_X22]
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ldp x24, x25, [sp, #S_X24]
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ldp x26, x27, [sp, #S_X26]
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ldp x28, x29, [sp, #S_X28]
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.endm
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ENTRY(kretprobe_trampoline)
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sub sp, sp, #S_FRAME_SIZE
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save_all_base_regs
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mov x0, sp
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bl trampoline_probe_handler
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/*
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* Replace trampoline address in lr with actual orig_ret_addr return
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* address.
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*/
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mov lr, x0
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restore_all_base_regs
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add sp, sp, #S_FRAME_SIZE
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ret
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ENDPROC(kretprobe_trampoline)
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