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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /arch/arm/kernel/entry-ftrace.S
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/arm/kernel/entry-ftrace.S')
-rw-r--r--arch/arm/kernel/entry-ftrace.S288
1 files changed, 288 insertions, 0 deletions
diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
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+++ b/arch/arm/kernel/entry-ftrace.S
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+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <asm/assembler.h>
+#include <asm/ftrace.h>
+#include <asm/unwind.h>
+
+#include "entry-header.S"
+
+/*
+ * When compiling with -pg, gcc inserts a call to the mcount routine at the
+ * start of every function. In mcount, apart from the function's address (in
+ * lr), we need to get hold of the function's caller's address.
+ *
+ * Newer GCCs (4.4+) solve this problem by using a version of mcount with call
+ * sites like:
+ *
+ * push {lr}
+ * bl __gnu_mcount_nc
+ *
+ * With these compilers, frame pointers are not necessary.
+ *
+ * mcount can be thought of as a function called in the middle of a subroutine
+ * call. As such, it needs to be transparent for both the caller and the
+ * callee: the original lr needs to be restored when leaving mcount, and no
+ * registers should be clobbered.
+ *
+ * When using dynamic ftrace, we patch out the mcount call by a "add sp, #4"
+ * instead of the __gnu_mcount_nc call (see arch/arm/kernel/ftrace.c).
+ */
+
+.macro mcount_adjust_addr rd, rn
+ bic \rd, \rn, #1 @ clear the Thumb bit if present
+ sub \rd, \rd, #MCOUNT_INSN_SIZE
+.endm
+
+.macro __mcount suffix
+ mcount_enter
+ ldr_va r2, ftrace_trace_function
+ badr r0, .Lftrace_stub
+ cmp r0, r2
+ bne 1f
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ ldr_va r2, ftrace_graph_return
+ cmp r0, r2
+ bne ftrace_graph_caller\suffix
+
+ ldr_va r2, ftrace_graph_entry
+ mov_l r0, ftrace_graph_entry_stub
+ cmp r0, r2
+ bne ftrace_graph_caller\suffix
+#endif
+
+ mcount_exit
+
+1: mcount_get_lr r1 @ lr of instrumented func
+ mcount_adjust_addr r0, lr @ instrumented function
+ badr lr, 2f
+ mov pc, r2
+2: mcount_exit
+.endm
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+
+.macro __ftrace_regs_caller
+
+ str lr, [sp, #-8]! @ store LR as PC and make space for CPSR/OLD_R0,
+ @ OLD_R0 will overwrite previous LR
+
+ ldr lr, [sp, #8] @ get previous LR
+
+ str r0, [sp, #8] @ write r0 as OLD_R0 over previous LR
+
+ str lr, [sp, #-4]! @ store previous LR as LR
+
+ add lr, sp, #16 @ move in LR the value of SP as it was
+ @ before the push {lr} of the mcount mechanism
+
+ push {r0-r11, ip, lr}
+
+ @ stack content at this point:
+ @ 0 4 48 52 56 60 64 68 72
+ @ R0 | R1 | ... | IP | SP + 4 | previous LR | LR | PSR | OLD_R0 |
+
+ mov r3, sp @ struct pt_regs*
+
+ ldr_va r2, function_trace_op @ pointer to the current
+ @ function tracing op
+
+ ldr r1, [sp, #S_LR] @ lr of instrumented func
+
+ ldr lr, [sp, #S_PC] @ get LR
+
+ mcount_adjust_addr r0, lr @ instrumented function
+
+ .globl ftrace_regs_call
+ftrace_regs_call:
+ bl ftrace_stub
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ .globl ftrace_graph_regs_call
+ftrace_graph_regs_call:
+ARM( mov r0, r0 )
+THUMB( nop.w )
+#endif
+
+ @ pop saved regs
+ pop {r0-r11, ip, lr} @ restore r0 through r12
+ ldr lr, [sp], #4 @ restore LR
+ ldr pc, [sp], #12
+.endm
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+.macro __ftrace_graph_regs_caller
+
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
+ sub r0, fp, #4 @ lr of instrumented routine (parent)
+#else
+ add r0, sp, #S_LR
+#endif
+
+ @ called from __ftrace_regs_caller
+ ldr r1, [sp, #S_PC] @ instrumented routine (func)
+ mcount_adjust_addr r1, r1
+
+ mov r2, fpreg @ frame pointer
+ add r3, sp, #PT_REGS_SIZE
+ bl prepare_ftrace_return
+
+ @ pop registers saved in ftrace_regs_caller
+ pop {r0-r11, ip, lr} @ restore r0 through r12
+ ldr lr, [sp], #4 @ restore LR
+ ldr pc, [sp], #12
+
+.endm
+#endif
+#endif
+
+.macro __ftrace_caller suffix
+ mcount_enter
+
+ mcount_get_lr r1 @ lr of instrumented func
+ mcount_adjust_addr r0, lr @ instrumented function
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ ldr_va r2, function_trace_op @ pointer to the current
+ @ function tracing op
+ mov r3, #0 @ regs is NULL
+#endif
+
+ .globl ftrace_call\suffix
+ftrace_call\suffix:
+ bl ftrace_stub
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ .globl ftrace_graph_call\suffix
+ftrace_graph_call\suffix:
+ARM( mov r0, r0 )
+THUMB( nop.w )
+#endif
+
+ mcount_exit
+.endm
+
+.macro __ftrace_graph_caller
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
+ sub r0, fp, #4 @ &lr of instrumented routine (&parent)
+#else
+ add r0, sp, #20
+#endif
+#ifdef CONFIG_DYNAMIC_FTRACE
+ @ called from __ftrace_caller, saved in mcount_enter
+ ldr r1, [sp, #16] @ instrumented routine (func)
+ mcount_adjust_addr r1, r1
+#else
+ @ called from __mcount, untouched in lr
+ mcount_adjust_addr r1, lr @ instrumented routine (func)
+#endif
+ mov r2, fpreg @ frame pointer
+ add r3, sp, #24
+ bl prepare_ftrace_return
+ mcount_exit
+.endm
+
+/*
+ * __gnu_mcount_nc
+ */
+
+.macro mcount_enter
+/*
+ * This pad compensates for the push {lr} at the call site. Note that we are
+ * unable to unwind through a function which does not otherwise save its lr.
+ */
+ UNWIND(.pad #4)
+ stmdb sp!, {r0-r3, lr}
+ UNWIND(.save {r0-r3, lr})
+.endm
+
+.macro mcount_get_lr reg
+ ldr \reg, [sp, #20]
+.endm
+
+.macro mcount_exit
+ ldmia sp!, {r0-r3}
+ ldr lr, [sp, #4]
+ ldr pc, [sp], #8
+.endm
+
+ENTRY(__gnu_mcount_nc)
+UNWIND(.fnstart)
+#ifdef CONFIG_DYNAMIC_FTRACE
+ push {lr}
+ ldr lr, [sp, #4]
+ ldr pc, [sp], #8
+#else
+ __mcount
+#endif
+UNWIND(.fnend)
+ENDPROC(__gnu_mcount_nc)
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+ENTRY(ftrace_caller)
+UNWIND(.fnstart)
+ __ftrace_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_caller)
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ENTRY(ftrace_regs_caller)
+UNWIND(.fnstart)
+ __ftrace_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_regs_caller)
+#endif
+
+#endif
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ENTRY(ftrace_graph_caller)
+UNWIND(.fnstart)
+ __ftrace_graph_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_graph_caller)
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ENTRY(ftrace_graph_regs_caller)
+UNWIND(.fnstart)
+ __ftrace_graph_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_graph_regs_caller)
+#endif
+#endif
+
+.purgem mcount_enter
+.purgem mcount_get_lr
+.purgem mcount_exit
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ENTRY(return_to_handler)
+ stmdb sp!, {r0-r3}
+ add r0, sp, #16 @ sp at exit of instrumented routine
+ bl ftrace_return_to_handler
+ mov lr, r0 @ r0 has real ret addr
+ ldmia sp!, {r0-r3}
+ ret lr
+ENDPROC(return_to_handler)
+#endif
+
+ENTRY(ftrace_stub)
+.Lftrace_stub:
+ ret lr
+ENDPROC(ftrace_stub)
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+ __INIT
+
+ .macro init_tramp, dst:req
+ENTRY(\dst\()_from_init)
+ ldr pc, =\dst
+ENDPROC(\dst\()_from_init)
+ .endm
+
+ init_tramp ftrace_caller
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ init_tramp ftrace_regs_caller
+#endif
+#endif