Re: [PATCH v2 5/5] powerpc64/ftrace: Implement support for ftrace_regs_caller()
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2018-03-21 13:59:15
On Wed, 21 Mar 2018 16:13:22 +0530 "Naveen N. Rao" [off-list ref] wrote:
int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
{
mod->arch.toc = my_r2(sechdrs, mod);
- mod->arch.tramp = create_ftrace_stub(sechdrs, mod);
+ mod->arch.tramp = create_ftrace_stub(sechdrs, mod,
+ (unsigned long)ftrace_caller);
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ mod->arch.tramp_regs = create_ftrace_stub(sechdrs, mod,
+ (unsigned long)ftrace_regs_caller);So you only reference ftrace_regs_caller if you have DYNAMIC_FTRACE_WITH_REGS defined?
+ if (!mod->arch.tramp_regs) + return -ENOENT; +#endif if (!mod->arch.tramp) return -ENOENT;
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S index 8f2380304ef1..7b81db85f76e 100644 --- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S +++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S@@ -20,8 +20,8 @@ #ifdef CONFIG_DYNAMIC_FTRACE /* * - * ftrace_caller() is the function that replaces _mcount() when ftrace is - * active. + * ftrace_caller()/ftrace_regs_caller() is the function that replaces _mcount() + * when ftrace is active. * * We arrive here after a function A calls function B, and we are the trace * function for B. When we enter r1 points to A's stack frame, B has not yet@@ -37,7 +37,7 @@ * Our job is to save the register state into a struct pt_regs (on the stack) * and then arrange for the ftrace function to be called. */
Perhaps you want to add: #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS here.
quoted hunk ↗ jump to hunk
-_GLOBAL(ftrace_caller) +_GLOBAL(ftrace_regs_caller) /* Save the original return address in A's stack frame */ std r0,LRSAVE(r1)@@ -100,8 +100,8 @@ _GLOBAL(ftrace_caller) addi r6, r1 ,STACK_FRAME_OVERHEAD /* ftrace_call(r3, r4, r5, r6) */ -.globl ftrace_call -ftrace_call: +.globl ftrace_regs_call +ftrace_regs_call: bl ftrace_stub nop@@ -162,6 +162,7 @@ ftrace_call: bne- livepatch_handler #endif +ftrace_caller_common: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_call ftrace_graph_call:@@ -182,6 +183,66 @@ ftrace_no_trace: mtlr r0 bctr +_GLOBAL(ftrace_caller) + /* Save the original return address in A's stack frame */ + std r0, LRSAVE(r1) + + /* Create our stack frame + pt_regs */ + stdu r1, -SWITCH_FRAME_SIZE(r1) + + /* Save all gprs to pt_regs */ + SAVE_8GPRS(3, r1) + + lbz r3, PACA_FTRACE_DISABLED(r13) + cmpdi r3, 0 + beq ftrace_no_trace
Of course you would need to keep the ftrace_no_trace part out of the #if block then. -- Steve
+ + /* Get the _mcount() call site out of LR */ + mflr r7 + std r7, _NIP(r1) + + /* Save callee's TOC in the ABI compliant location */ + std r2, 24(r1) + ld r2, PACATOC(r13) /* get kernel TOC in r2 */ + + addis r3, r2, function_trace_op@toc@ha + addi r3, r3, function_trace_op@toc@l + ld r5, 0(r3) + + /* Calculate ip from nip-4 into r3 for call below */ + subi r3, r7, MCOUNT_INSN_SIZE + + /* Put the original return address in r4 as parent_ip */ + mr r4, r0 + + /* Set pt_regs to NULL */ + li r6, 0 + + /* ftrace_call(r3, r4, r5, r6) */ +.globl ftrace_call +ftrace_call: + bl ftrace_stub + nop + + ld r3, _NIP(r1) + mtctr r3 + + /* Restore gprs */ + REST_8GPRS(3,r1) + + /* Restore callee's TOC */ + ld r2, 24(r1) + + /* Pop our stack frame */ + addi r1, r1, SWITCH_FRAME_SIZE + + /* Reload original LR */ + ld r0, LRSAVE(r1) + mtlr r0 + + /* Handle function_graph or go back */ + b ftrace_caller_common + #ifdef CONFIG_LIVEPATCH /* * This function runs in the mcount context, between two functions. As