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63bf38ff5b
So far, s390 registered a krobe on __kretprobe_trampoline which is called everytime a kretprobe fires. This kprobe would then determine the correct return address and adjust the psw accordingly, such that the kretprobe would branch to the appropriate address after completion. Some other archs handle kretprobes without such an additional kprobe. This approach is adopted to s390 with this patch. Furthermore, the __kretprobe_trampoline now uses an assembler function to correctly gather the register and psw content to be passed to the registered kretprobe handler as struct pt_regs. After completion, the register content and the psw are set based on the contents of said pt_regs struct. Note that a change to the psw address in struct pt_regs will not have an impact, as the probe will still return to the original return address of the probed function. The return address is now recovered by using the appropriate function arch_kretprobe_fixup_return. The no longer needed kprobe is removed. Reviewed-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Tobias Huschle <huschle@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
167 lines
4.1 KiB
ArmAsm
167 lines
4.1 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright IBM Corp. 2008, 2009
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*
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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/ftrace.h>
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#include <asm/nospec-insn.h>
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#include <asm/ptrace.h>
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#include <asm/export.h>
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#define STACK_FRAME_SIZE (STACK_FRAME_OVERHEAD + __PT_SIZE)
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#define STACK_PTREGS (STACK_FRAME_OVERHEAD)
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#define STACK_PTREGS_GPRS (STACK_PTREGS + __PT_GPRS)
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#define STACK_PTREGS_PSW (STACK_PTREGS + __PT_PSW)
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#define STACK_PTREGS_ORIG_GPR2 (STACK_PTREGS + __PT_ORIG_GPR2)
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#define STACK_PTREGS_FLAGS (STACK_PTREGS + __PT_FLAGS)
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/* packed stack: allocate just enough for r14, r15 and backchain */
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#define TRACED_FUNC_FRAME_SIZE 24
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#ifdef CONFIG_FUNCTION_TRACER
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GEN_BR_THUNK %r1
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GEN_BR_THUNK %r14
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.section .kprobes.text, "ax"
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ENTRY(ftrace_stub)
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BR_EX %r14
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ENDPROC(ftrace_stub)
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.macro ftrace_regs_entry, allregs=0
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stg %r14,(__SF_GPRS+8*8)(%r15) # save traced function caller
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.if \allregs == 1
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# save psw mask
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# don't put any instructions clobbering CC before this point
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epsw %r1,%r14
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risbg %r14,%r1,0,31,32
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.endif
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lgr %r1,%r15
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# allocate stack frame for ftrace_caller to contain traced function
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aghi %r15,-TRACED_FUNC_FRAME_SIZE
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stg %r1,__SF_BACKCHAIN(%r15)
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stg %r0,(__SF_GPRS+8*8)(%r15)
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stg %r15,(__SF_GPRS+9*8)(%r15)
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# allocate pt_regs and stack frame for ftrace_trace_function
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aghi %r15,-STACK_FRAME_SIZE
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stg %r1,(STACK_PTREGS_GPRS+15*8)(%r15)
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xc STACK_PTREGS_ORIG_GPR2(8,%r15),STACK_PTREGS_ORIG_GPR2(%r15)
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.if \allregs == 1
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stg %r14,(STACK_PTREGS_PSW)(%r15)
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mvghi STACK_PTREGS_FLAGS(%r15),_PIF_FTRACE_FULL_REGS
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.else
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xc STACK_PTREGS_FLAGS(8,%r15),STACK_PTREGS_FLAGS(%r15)
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.endif
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lg %r14,(__SF_GPRS+8*8)(%r1) # restore original return address
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aghi %r1,-TRACED_FUNC_FRAME_SIZE
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stg %r1,__SF_BACKCHAIN(%r15)
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stg %r0,(STACK_PTREGS_PSW+8)(%r15)
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stmg %r2,%r14,(STACK_PTREGS_GPRS+2*8)(%r15)
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.endm
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SYM_CODE_START(ftrace_regs_caller)
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ftrace_regs_entry 1
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j ftrace_common
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SYM_CODE_END(ftrace_regs_caller)
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SYM_CODE_START(ftrace_caller)
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ftrace_regs_entry 0
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j ftrace_common
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SYM_CODE_END(ftrace_caller)
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SYM_CODE_START(ftrace_common)
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#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
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aghik %r2,%r0,-MCOUNT_INSN_SIZE
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lgrl %r4,function_trace_op
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lgrl %r1,ftrace_func
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#else
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lgr %r2,%r0
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aghi %r2,-MCOUNT_INSN_SIZE
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larl %r4,function_trace_op
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lg %r4,0(%r4)
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larl %r1,ftrace_func
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lg %r1,0(%r1)
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#endif
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lgr %r3,%r14
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la %r5,STACK_PTREGS(%r15)
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BASR_EX %r14,%r1
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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# The j instruction gets runtime patched to a nop instruction.
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# See ftrace_enable_ftrace_graph_caller.
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SYM_INNER_LABEL(ftrace_graph_caller, SYM_L_GLOBAL)
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j .Lftrace_graph_caller_end
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lmg %r2,%r3,(STACK_PTREGS_GPRS+14*8)(%r15)
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lg %r4,(STACK_PTREGS_PSW+8)(%r15)
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brasl %r14,prepare_ftrace_return
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stg %r2,(STACK_PTREGS_GPRS+14*8)(%r15)
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.Lftrace_graph_caller_end:
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#endif
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lg %r0,(STACK_PTREGS_PSW+8)(%r15)
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#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
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ltg %r1,STACK_PTREGS_ORIG_GPR2(%r15)
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locgrz %r1,%r0
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#else
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lg %r1,STACK_PTREGS_ORIG_GPR2(%r15)
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ltgr %r1,%r1
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jnz 0f
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lgr %r1,%r0
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#endif
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0: lmg %r2,%r15,(STACK_PTREGS_GPRS+2*8)(%r15)
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BR_EX %r1
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SYM_CODE_END(ftrace_common)
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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SYM_FUNC_START(return_to_handler)
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stmg %r2,%r5,32(%r15)
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lgr %r1,%r15
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aghi %r15,-STACK_FRAME_OVERHEAD
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stg %r1,__SF_BACKCHAIN(%r15)
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brasl %r14,ftrace_return_to_handler
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aghi %r15,STACK_FRAME_OVERHEAD
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lgr %r14,%r2
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lmg %r2,%r5,32(%r15)
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BR_EX %r14
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SYM_FUNC_END(return_to_handler)
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#endif
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifdef CONFIG_KPROBES
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SYM_FUNC_START(__kretprobe_trampoline)
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stg %r14,(__SF_GPRS+8*8)(%r15)
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lay %r15,-STACK_FRAME_SIZE(%r15)
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stmg %r0,%r14,STACK_PTREGS_GPRS(%r15)
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# store original stack pointer in backchain and pt_regs
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lay %r7,STACK_FRAME_SIZE(%r15)
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stg %r7,__SF_BACKCHAIN(%r15)
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stg %r7,STACK_PTREGS_GPRS+(15*8)(%r15)
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# store full psw
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epsw %r2,%r3
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risbg %r3,%r2,0,31,32
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stg %r3,STACK_PTREGS_PSW(%r15)
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larl %r1,__kretprobe_trampoline
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stg %r1,STACK_PTREGS_PSW+8(%r15)
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lay %r2,STACK_PTREGS(%r15)
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brasl %r14,trampoline_probe_handler
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mvc __SF_EMPTY(16,%r7),STACK_PTREGS_PSW(%r15)
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lmg %r0,%r15,STACK_PTREGS_GPRS(%r15)
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lpswe __SF_EMPTY(%r15)
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SYM_FUNC_END(__kretprobe_trampoline)
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#endif /* CONFIG_KPROBES */
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