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parisc: add dynamic ftrace
This patch implements dynamic ftrace for PA-RISC. The required mcount call sequences can get pretty long, so instead of patching the whole call sequence out of the functions, we are using -fpatchable-function-entry from gcc. This puts a configurable amount of NOPS before/at the start of the function. Taking do_sys_open() as example, which would look like this when the call is patched out: 1036b248: 08 00 02 40 nop 1036b24c: 08 00 02 40 nop 1036b250: 08 00 02 40 nop 1036b254: 08 00 02 40 nop 1036b258 <do_sys_open>: 1036b258: 08 00 02 40 nop 1036b25c: 08 03 02 41 copy r3,r1 1036b260: 6b c2 3f d9 stw rp,-14(sp) 1036b264: 08 1e 02 43 copy sp,r3 1036b268: 6f c1 01 00 stw,ma r1,80(sp) When ftrace gets enabled for this function the kernel will patch these NOPs to: 1036b248: 10 19 57 20 <address of ftrace> 1036b24c: 6f c1 00 80 stw,ma r1,40(sp) 1036b250: 48 21 3f d1 ldw -18(r1),r1 1036b254: e8 20 c0 02 bv,n r0(r1) 1036b258 <do_sys_open>: 1036b258: e8 3f 1f df b,l,n .-c,r1 1036b25c: 08 03 02 41 copy r3,r1 1036b260: 6b c2 3f d9 stw rp,-14(sp) 1036b264: 08 1e 02 43 copy sp,r3 1036b268: 6f c1 01 00 stw,ma r1,80(sp) So the first NOP in do_sys_open() will be patched to jump backwards into some minimal trampoline code which pushes a stackframe, saves r1 which holds the return address, loads the address of the real ftrace function, and branches to that location. For 64 Bit things are getting a bit more complicated (and longer) because we must make sure that the address of ftrace location is 8 byte aligned, and the offset passed to ldd for fetching the address is 8 byte aligned as well. Note that gcc has a bug which misplaces the function label, and needs a patch to make dynamic ftrace work. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90751 for details. Signed-off-by: Sven Schnelle <svens@stackframe.org> Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Sven Schnelle
Helge Deller
parent
2809b392a6
commit
6ca6366220
@ -59,6 +59,8 @@ config PARISC
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select HAVE_ARCH_KGDB
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select HAVE_KPROBES
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select HAVE_KRETPROBES
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select HAVE_DYNAMIC_FTRACE if $(cc-option,-fpatchable-function-entry=1,1)
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select HAVE_FTRACE_MCOUNT_RECORD if HAVE_DYNAMIC_FTRACE
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help
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The PA-RISC microprocessor is designed by Hewlett-Packard and used
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@ -47,6 +47,24 @@ ifneq ($(SUBARCH),$(UTS_MACHINE))
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endif
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endif
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ifdef CONFIG_DYNAMIC_FTRACE
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ifdef CONFIG_64BIT
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NOP_COUNT := 8
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else
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NOP_COUNT := 5
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endif
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export CC_USING_RECORD_MCOUNT:=1
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export CC_USING_PATCHABLE_FUNCTION_ENTRY:=1
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KBUILD_AFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY=1
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KBUILD_CFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY=1 \
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-DFTRACE_PATCHABLE_FUNCTION_SIZE=$(NOP_COUNT)
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CC_FLAGS_FTRACE := -fpatchable-function-entry=$(NOP_COUNT),$(shell echo $$(($(NOP_COUNT)-1)))
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KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/parisc/kernel/module.lds
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endif
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OBJCOPY_FLAGS =-O binary -R .note -R .comment -S
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cflags-y := -pipe
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@ -5,12 +5,23 @@
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#ifndef __ASSEMBLY__
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extern void mcount(void);
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#define MCOUNT_ADDR ((unsigned long)mcount)
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#define MCOUNT_INSN_SIZE 4
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#define CC_USING_NOP_MCOUNT
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extern unsigned long sys_call_table[];
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extern unsigned long return_address(unsigned int);
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_caller(void);
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struct dyn_arch_ftrace {
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};
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unsigned long ftrace_call_adjust(unsigned long addr);
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#endif
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#define ftrace_return_address(n) return_address(n)
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#endif /* __ASSEMBLY__ */
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@ -14,10 +14,11 @@ obj-y := cache.o pacache.o setup.o pdt.o traps.o time.o irq.o \
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ifdef CONFIG_FUNCTION_TRACER
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# Do not profile debug and lowlevel utilities
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CFLAGS_REMOVE_ftrace.o = -pg
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CFLAGS_REMOVE_cache.o = -pg
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CFLAGS_REMOVE_perf.o = -pg
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CFLAGS_REMOVE_unwind.o = -pg
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CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
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CFLAGS_REMOVE_cache.o = $(CC_FLAGS_FTRACE)
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CFLAGS_REMOVE_perf.o = $(CC_FLAGS_FTRACE)
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CFLAGS_REMOVE_unwind.o = $(CC_FLAGS_FTRACE)
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CFLAGS_REMOVE_patch.o = $(CC_FLAGS_FTRACE)
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endif
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obj-$(CONFIG_SMP) += smp.o
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@ -2012,6 +2012,70 @@ ftrace_stub:
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#endif
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ENDPROC_CFI(mcount)
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#ifdef CONFIG_DYNAMIC_FTRACE
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#ifdef CONFIG_64BIT
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#define FTRACE_FRAME_SIZE (2*FRAME_SIZE)
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#else
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#define FTRACE_FRAME_SIZE FRAME_SIZE
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#endif
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ENTRY_CFI(ftrace_caller, caller,frame=FTRACE_FRAME_SIZE,CALLS,SAVE_RP,SAVE_SP)
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ftrace_caller:
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.global ftrace_caller
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STREG %r3, -FTRACE_FRAME_SIZE+1*REG_SZ(%sp)
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ldo -FTRACE_FRAME_SIZE(%sp), %r3
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STREG %rp, -RP_OFFSET(%r3)
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/* Offset 0 is already allocated for %r1 */
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STREG %r23, 2*REG_SZ(%r3)
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STREG %r24, 3*REG_SZ(%r3)
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STREG %r25, 4*REG_SZ(%r3)
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STREG %r26, 5*REG_SZ(%r3)
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STREG %r28, 6*REG_SZ(%r3)
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STREG %r29, 7*REG_SZ(%r3)
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#ifdef CONFIG_64BIT
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STREG %r19, 8*REG_SZ(%r3)
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STREG %r20, 9*REG_SZ(%r3)
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STREG %r21, 10*REG_SZ(%r3)
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STREG %r22, 11*REG_SZ(%r3)
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STREG %r27, 12*REG_SZ(%r3)
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STREG %r31, 13*REG_SZ(%r3)
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loadgp
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ldo -16(%sp),%r29
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#endif
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LDREG 0(%r3), %r25
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copy %rp, %r26
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ldo -8(%r25), %r25
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b,l ftrace_function_trampoline, %rp
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copy %r3, %r24
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LDREG -RP_OFFSET(%r3), %rp
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LDREG 2*REG_SZ(%r3), %r23
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LDREG 3*REG_SZ(%r3), %r24
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LDREG 4*REG_SZ(%r3), %r25
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LDREG 5*REG_SZ(%r3), %r26
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LDREG 6*REG_SZ(%r3), %r28
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LDREG 7*REG_SZ(%r3), %r29
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#ifdef CONFIG_64BIT
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LDREG 8*REG_SZ(%r3), %r19
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LDREG 9*REG_SZ(%r3), %r20
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LDREG 10*REG_SZ(%r3), %r21
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LDREG 11*REG_SZ(%r3), %r22
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LDREG 12*REG_SZ(%r3), %r27
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LDREG 13*REG_SZ(%r3), %r31
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#endif
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LDREG 1*REG_SZ(%r3), %r3
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LDREGM -FTRACE_FRAME_SIZE(%sp), %r1
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/* Adjust return point to jump back to beginning of traced function */
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ldo -4(%r1), %r1
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bv,n (%r1)
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ENDPROC_CFI(ftrace_caller)
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#endif
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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.align 8
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ENTRY_CFI(return_to_handler, caller,frame=FRAME_SIZE)
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@ -7,17 +7,17 @@
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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*
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* future possible enhancements:
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* - add CONFIG_DYNAMIC_FTRACE
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* - add CONFIG_STACK_TRACER
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*/
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#include <linux/init.h>
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#include <linux/ftrace.h>
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#include <linux/uaccess.h>
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#include <asm/assembly.h>
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#include <asm/sections.h>
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#include <asm/ftrace.h>
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#include <asm/patch.h>
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#define __hot __attribute__ ((__section__ (".text.hot")))
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@ -50,13 +50,11 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
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unsigned long self_addr,
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unsigned long org_sp_gr3)
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{
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extern ftrace_func_t ftrace_trace_function; /* depends on CONFIG_DYNAMIC_FTRACE */
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if (ftrace_trace_function != ftrace_stub) {
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/* struct ftrace_ops *op, struct pt_regs *regs); */
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ftrace_trace_function(parent, self_addr, NULL, NULL);
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return;
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}
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#ifndef CONFIG_DYNAMIC_FTRACE
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extern ftrace_func_t ftrace_trace_function;
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#endif
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if (ftrace_trace_function != ftrace_stub)
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ftrace_trace_function(self_addr, parent, NULL, NULL);
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub ||
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@ -75,3 +73,116 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
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#endif
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}
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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int ftrace_enable_ftrace_graph_caller(void)
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{
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return 0;
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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int __init ftrace_dyn_arch_init(void)
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{
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return 0;
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}
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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return 0;
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}
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unsigned long ftrace_call_adjust(unsigned long addr)
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{
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return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4;
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}
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
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u32 *tramp;
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int size, ret, i;
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void *ip;
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#ifdef CONFIG_64BIT
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unsigned long addr2 =
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(unsigned long)dereference_function_descriptor((void *)addr);
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u32 ftrace_trampoline[] = {
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0x73c10208, /* std,ma r1,100(sp) */
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0x0c2110c1, /* ldd -10(r1),r1 */
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0xe820d002, /* bve,n (r1) */
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addr2 >> 32,
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addr2 & 0xffffffff,
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0xe83f1fd7, /* b,l,n .-14,r1 */
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};
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u32 ftrace_trampoline_unaligned[] = {
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addr2 >> 32,
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addr2 & 0xffffffff,
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0x37de0200, /* ldo 100(sp),sp */
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0x73c13e01, /* std r1,-100(sp) */
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0x34213ff9, /* ldo -4(r1),r1 */
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0x50213fc1, /* ldd -20(r1),r1 */
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0xe820d002, /* bve,n (r1) */
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0xe83f1fcf, /* b,l,n .-20,r1 */
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};
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BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) >
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FTRACE_PATCHABLE_FUNCTION_SIZE);
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#else
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u32 ftrace_trampoline[] = {
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(u32)addr,
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0x6fc10080, /* stw,ma r1,40(sp) */
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0x48213fd1, /* ldw -18(r1),r1 */
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0xe820c002, /* bv,n r0(r1) */
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0xe83f1fdf, /* b,l,n .-c,r1 */
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};
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#endif
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BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) >
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FTRACE_PATCHABLE_FUNCTION_SIZE);
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size = sizeof(ftrace_trampoline);
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tramp = ftrace_trampoline;
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#ifdef CONFIG_64BIT
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if (rec->ip & 0x4) {
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size = sizeof(ftrace_trampoline_unaligned);
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tramp = ftrace_trampoline_unaligned;
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}
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#endif
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ip = (void *)(rec->ip + 4 - size);
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ret = probe_kernel_read(insn, ip, size);
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if (ret)
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return ret;
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for (i = 0; i < size / 4; i++) {
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if (insn[i] != INSN_NOP)
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return -EINVAL;
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}
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__patch_text_multiple(ip, tramp, size);
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return 0;
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}
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int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
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unsigned long addr)
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{
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u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
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int i;
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for (i = 0; i < ARRAY_SIZE(insn); i++)
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insn[i] = INSN_NOP;
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__patch_text_multiple((void *)rec->ip + 4 - sizeof(insn),
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insn, sizeof(insn));
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return 0;
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}
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#endif
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@ -858,6 +858,7 @@ int module_finalize(const Elf_Ehdr *hdr,
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const char *strtab = NULL;
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const Elf_Shdr *s;
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char *secstrings;
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int err, symindex = -1;
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Elf_Sym *newptr, *oldptr;
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Elf_Shdr *symhdr = NULL;
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#ifdef DEBUG
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@ -884,6 +885,7 @@ int module_finalize(const Elf_Ehdr *hdr,
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if(sechdrs[i].sh_type == SHT_SYMTAB
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&& (sechdrs[i].sh_flags & SHF_ALLOC)) {
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int strindex = sechdrs[i].sh_link;
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symindex = i;
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/* FIXME: AWFUL HACK
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* The cast is to drop the const from
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* the sechdrs pointer */
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@ -939,8 +941,24 @@ int module_finalize(const Elf_Ehdr *hdr,
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if (!strcmp(".altinstructions", secname))
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/* patch .altinstructions */
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apply_alternatives(aseg, aseg + s->sh_size, me->name);
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}
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/* For 32 bit kernels we're compiling modules with
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* -ffunction-sections so we must relocate the addresses in the
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*__mcount_loc section.
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*/
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if (symindex != -1 && !strcmp(secname, "__mcount_loc")) {
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if (s->sh_type == SHT_REL)
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err = apply_relocate((Elf_Shdr *)sechdrs,
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strtab, symindex,
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s - sechdrs, me);
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else if (s->sh_type == SHT_RELA)
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err = apply_relocate_add((Elf_Shdr *)sechdrs,
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strtab, symindex,
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s - sechdrs, me);
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if (err)
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return err;
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}
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}
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return 0;
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}
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7
arch/parisc/kernel/module.lds
Normal file
7
arch/parisc/kernel/module.lds
Normal file
@ -0,0 +1,7 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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SECTIONS {
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__mcount_loc : {
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*(__patchable_function_entries)
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}
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}
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@ -18,6 +18,8 @@
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*(.data..vm0.pgd) \
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*(.data..vm0.pte)
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#define CC_USING_PATCHABLE_FUNCTION_ENTRY
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#include <asm-generic/vmlinux.lds.h>
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/* needed for the processor specific cache alignment size */
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@ -10,7 +10,7 @@
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#include <asm/cacheflush.h>
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#include <asm/fixmap.h>
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void set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
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void notrace set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
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{
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unsigned long vaddr = __fix_to_virt(idx);
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pgd_t *pgd = pgd_offset_k(vaddr);
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@ -28,7 +28,7 @@ void set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
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flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
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}
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void clear_fixmap(enum fixed_addresses idx)
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void notrace clear_fixmap(enum fixed_addresses idx)
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{
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unsigned long vaddr = __fix_to_virt(idx);
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pgd_t *pgd = pgd_offset_k(vaddr);
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@ -110,10 +110,17 @@
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#endif
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#ifdef CONFIG_FTRACE_MCOUNT_RECORD
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#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
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#define MCOUNT_REC() . = ALIGN(8); \
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__start_mcount_loc = .; \
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KEEP(*(__patchable_function_entries)) \
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__stop_mcount_loc = .;
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#else
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#define MCOUNT_REC() . = ALIGN(8); \
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__start_mcount_loc = .; \
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KEEP(*(__mcount_loc)) \
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__stop_mcount_loc = .;
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#endif
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#else
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#define MCOUNT_REC()
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#endif
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