| Message ID | 9d7df9e4fc98a86051489f61d3c9bc67f92f7e27.1645099283.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v1,1/4] powerpc/ftrace: Don't use lmw/stmw in ftrace_regs_caller() | expand |
Christophe Leroy wrote: > ftrace_caller() and frace_regs_caller() have now a lot in common. > > Refactor them using GAS macros. Thanks for doing this - this looks much better. > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > arch/powerpc/kernel/trace/ftrace_mprofile.S | 147 ++++++-------------- > 1 file changed, 45 insertions(+), 102 deletions(-) > > diff --git a/arch/powerpc/kernel/trace/ftrace_mprofile.S b/arch/powerpc/kernel/trace/ftrace_mprofile.S > index 76dab07fd8fd..630b2de9957b 100644 > --- a/arch/powerpc/kernel/trace/ftrace_mprofile.S > +++ b/arch/powerpc/kernel/trace/ftrace_mprofile.S > @@ -32,7 +32,7 @@ > * 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. > */ > -_GLOBAL(ftrace_regs_caller) > +.macro ftrace_regs_entry allregs > /* Save the original return address in A's stack frame */ > #ifdef CONFIG_MPROFILE_KERNEL > PPC_STL r0,LRSAVE(r1) > @@ -43,7 +43,7 @@ _GLOBAL(ftrace_regs_caller) > > /* Save all gprs to pt_regs */ > SAVE_GPR(0, r1) > - SAVE_GPRS(2, 11, r1) > + SAVE_GPRS(3, 10, r1) > > #ifdef CONFIG_PPC64 > /* Ok to continue? */ > @@ -52,17 +52,29 @@ _GLOBAL(ftrace_regs_caller) > beq ftrace_no_trace > #endif The ability to disable ftrace in certain code paths through paca_struct->ftrace_enabled will also be relevant on ppc32 - it will be nice if it can be introduced there. For this series though: Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> - Naveen
Le 03/03/2022 à 17:59, Naveen N. Rao a écrit : > Christophe Leroy wrote: >> ftrace_caller() and frace_regs_caller() have now a lot in common. >> >> Refactor them using GAS macros. > > Thanks for doing this - this looks much better. > >> >> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> >> --- >> arch/powerpc/kernel/trace/ftrace_mprofile.S | 147 ++++++-------------- >> 1 file changed, 45 insertions(+), 102 deletions(-) >> >> diff --git a/arch/powerpc/kernel/trace/ftrace_mprofile.S >> b/arch/powerpc/kernel/trace/ftrace_mprofile.S >> index 76dab07fd8fd..630b2de9957b 100644 >> --- a/arch/powerpc/kernel/trace/ftrace_mprofile.S >> +++ b/arch/powerpc/kernel/trace/ftrace_mprofile.S >> @@ -32,7 +32,7 @@ >> * 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. >> */ >> -_GLOBAL(ftrace_regs_caller) >> +.macro ftrace_regs_entry allregs >> /* Save the original return address in A's stack frame */ >> #ifdef CONFIG_MPROFILE_KERNEL >> PPC_STL r0,LRSAVE(r1) >> @@ -43,7 +43,7 @@ _GLOBAL(ftrace_regs_caller) >> >> /* Save all gprs to pt_regs */ >> SAVE_GPR(0, r1) >> - SAVE_GPRS(2, 11, r1) >> + SAVE_GPRS(3, 10, r1) >> >> #ifdef CONFIG_PPC64 >> /* Ok to continue? */ >> @@ -52,17 +52,29 @@ _GLOBAL(ftrace_regs_caller) >> beq ftrace_no_trace >> #endif > > The ability to disable ftrace in certain code paths through > paca_struct->ftrace_enabled will also be relevant on ppc32 - it will be > nice if it can be introduced there. Ah ? I understood from commit ea678ac627e0 ("powerpc64/ftrace: Add a field in paca to disable ftrace in unsafe code paths") that it was for when it runs in real mode. PPC32 doesn't run any C code in real mode. Are there any other situations that real_mode where we'd like to disable it ? If so we could use the thread_struct as we don't have paca on PPC32. Christophe
Christophe Leroy wrote: > > > Le 03/03/2022 à 17:59, Naveen N. Rao a écrit : >> Christophe Leroy wrote: >> >> The ability to disable ftrace in certain code paths through >> paca_struct->ftrace_enabled will also be relevant on ppc32 - it will be >> nice if it can be introduced there. > > Ah ? I understood from commit ea678ac627e0 ("powerpc64/ftrace: Add a > field in paca to disable ftrace in unsafe code paths") that it was for > when it runs in real mode. PPC32 doesn't run any C code in real mode. It likely isn't necessary in that case. > > Are there any other situations that real_mode where we'd like to disable > it ? If so we could use the thread_struct as we don't have paca on PPC32. For ppc64, we use this flag to disable certain paths in kvm, kexec, mce/hmi and idle/hotplug. If none of those are problematic on ppc32, then this isn't necessary. Thanks, - Naveen
diff --git a/arch/powerpc/kernel/trace/ftrace_mprofile.S b/arch/powerpc/kernel/trace/ftrace_mprofile.S index 76dab07fd8fd..630b2de9957b 100644 --- a/arch/powerpc/kernel/trace/ftrace_mprofile.S +++ b/arch/powerpc/kernel/trace/ftrace_mprofile.S @@ -32,7 +32,7 @@ * 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. */ -_GLOBAL(ftrace_regs_caller) +.macro ftrace_regs_entry allregs /* Save the original return address in A's stack frame */ #ifdef CONFIG_MPROFILE_KERNEL PPC_STL r0,LRSAVE(r1) @@ -43,7 +43,7 @@ _GLOBAL(ftrace_regs_caller) /* Save all gprs to pt_regs */ SAVE_GPR(0, r1) - SAVE_GPRS(2, 11, r1) + SAVE_GPRS(3, 10, r1) #ifdef CONFIG_PPC64 /* Ok to continue? */ @@ -52,17 +52,29 @@ _GLOBAL(ftrace_regs_caller) beq ftrace_no_trace #endif - SAVE_GPRS(12, 31, r1) + .if \allregs == 1 + SAVE_GPR(2, r1) + SAVE_GPRS(11, 31, r1) + .else +#ifdef CONFIG_LIVEPATCH_64 + SAVE_GPR(14, r1) +#endif + .endif /* Save previous stack pointer (r1) */ addi r8, r1, SWITCH_FRAME_SIZE PPC_STL r8, GPR1(r1) + .if \allregs == 1 /* Load special regs for save below */ mfmsr r8 mfctr r9 mfxer r10 mfcr r11 + .else + /* Clear MSR to flag as ftrace_caller versus frace_regs_caller */ + li r8, 0 + .endif /* Get the _mcount() call site out of LR */ mflr r7 @@ -96,19 +108,17 @@ _GLOBAL(ftrace_regs_caller) /* Save special regs */ PPC_STL r8, _MSR(r1) + .if \allregs == 1 PPC_STL r9, _CTR(r1) PPC_STL r10, _XER(r1) PPC_STL r11, _CCR(r1) + .endif /* Load &pt_regs in r6 for call below */ addi r6, r1, STACK_FRAME_OVERHEAD +.endm - /* ftrace_call(r3, r4, r5, r6) */ -.globl ftrace_regs_call -ftrace_regs_call: - bl ftrace_stub - nop - +.macro ftrace_regs_exit allregs /* Load ctr with the possibly modified NIP */ PPC_LL r3, _NIP(r1) mtctr r3 @@ -118,7 +128,14 @@ ftrace_regs_call: #endif /* Restore gprs */ + .if \allregs == 1 REST_GPRS(2, 31, r1) + .else + REST_GPRS(3, 10, r1) +#ifdef CONFIG_LIVEPATCH_64 + REST_GPR(14, r1) +#endif + .endif /* Restore possibly modified LR */ PPC_LL r0, _LINK(r1) @@ -137,113 +154,39 @@ ftrace_regs_call: bne- livepatch_handler #endif bctr /* jump after _mcount site */ +.endm -_GLOBAL(ftrace_stub) - blr - -#ifdef CONFIG_PPC64 -ftrace_no_trace: - mflr r3 - mtctr r3 - REST_GPR(3, r1) - addi r1, r1, SWITCH_FRAME_SIZE - mtlr r0 - bctr -#endif +_GLOBAL(ftrace_regs_caller) + ftrace_regs_entry 1 + /* ftrace_call(r3, r4, r5, r6) */ +.globl ftrace_regs_call +ftrace_regs_call: + bl ftrace_stub + nop + ftrace_regs_exit 1 _GLOBAL(ftrace_caller) - /* Save the original return address in A's stack frame */ -#ifdef CONFIG_MPROFILE_KERNEL - PPC_STL r0, LRSAVE(r1) -#endif - - /* Create our stack frame + pt_regs */ - PPC_STLU r1, -SWITCH_FRAME_SIZE(r1) - - /* Save all gprs to pt_regs */ - SAVE_GPRS(3, 10, r1) - -#ifdef CONFIG_PPC64 - lbz r3, PACA_FTRACE_ENABLED(r13) - cmpdi r3, 0 - beq ftrace_no_trace -#endif - - /* Save previous stack pointer (r1) */ - addi r8, r1, SWITCH_FRAME_SIZE - PPC_STL r8, GPR1(r1) - - /* Get the _mcount() call site out of LR */ - mflr r7 - PPC_STL r7, _NIP(r1) - -#ifdef CONFIG_PPC64 - /* 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) -#else - lis r3,function_trace_op@ha - lwz r5,function_trace_op@l(r3) -#endif - -#ifdef CONFIG_LIVEPATCH_64 - SAVE_GPR(14, r1) - mr r14, r7 /* remember old NIP */ -#endif - /* 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 */ - PPC_STL r0, _LINK(r1) - mr r4, r0 - - /* Clear MSR to flag as ftrace_caller versus frace_regs_caller */ - li r8, 0 - PPC_STL r8, _MSR(r1) - - /* Load &pt_regs in r6 for call below */ - addi r6, r1, STACK_FRAME_OVERHEAD - + ftrace_regs_entry 0 /* ftrace_call(r3, r4, r5, r6) */ .globl ftrace_call ftrace_call: bl ftrace_stub nop + ftrace_regs_exit 0 - PPC_LL r3, _NIP(r1) - mtctr r3 - -#ifdef CONFIG_LIVEPATCH_64 - cmpd r14, r3 /* has NIP been altered? */ - REST_GPR(14, r1) -#endif - - /* Restore gprs */ - REST_GPRS(3, 10, r1) +_GLOBAL(ftrace_stub) + blr #ifdef CONFIG_PPC64 - /* Restore callee's TOC */ - ld r2, 24(r1) -#endif - - /* Restore possibly modified LR */ - PPC_LL r0, _LINK(r1) - mtlr r0 - - /* Pop our stack frame */ +ftrace_no_trace: + mflr r3 + mtctr r3 + REST_GPR(3, r1) addi r1, r1, SWITCH_FRAME_SIZE - -#ifdef CONFIG_LIVEPATCH_64 - /* Based on the cmpd above, if the NIP was altered handle livepatch */ - bne- livepatch_handler + mtlr r0 + bctr #endif - bctr /* jump after _mcount site */ - #ifdef CONFIG_LIVEPATCH_64 /* * This function runs in the mcount context, between two functions. As
ftrace_caller() and frace_regs_caller() have now a lot in common. Refactor them using GAS macros. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/powerpc/kernel/trace/ftrace_mprofile.S | 147 ++++++-------------- 1 file changed, 45 insertions(+), 102 deletions(-)