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Mon, 2 Jun 2025 12:36:19 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 204492004D; Mon, 2 Jun 2025 12:36:19 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 88DA220040; Mon, 2 Jun 2025 12:36:16 +0000 (GMT) Received: from [9.43.59.52] (unknown [9.43.59.52]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 2 Jun 2025 12:36:16 +0000 (GMT) Message-ID: Date: Mon, 2 Jun 2025 18:06:15 +0530 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] powerpc/ftrace: support CONFIG_FUNCTION_GRAPH_RETVAL To: Aditya Bodkhe , linuxppc-dev@lists.ozlabs.org Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, rostedt@goodmis.org, mhiramat@kernel.org, mark.rutland@arm.com, Aditya Bodkhe References: <20250528134820.74121-1-adityab1@linux.ibm.com> Content-Language: en-US From: Hari Bathini In-Reply-To: <20250528134820.74121-1-adityab1@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=GdwXnRXL c=1 sm=1 tr=0 ts=683d9aca cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=6IFa9wvqVegA:10 a=VnNF1IyMAAAA:8 a=GVWLqetRcDZtiWko8XAA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: 1h9eOEtw4XS8OmNcFYYnvUBdRPiJtwTC X-Proofpoint-ORIG-GUID: 9brDj5LJoIhQM1rXpA-BdHPY7e2ekXHS X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNjAyMDEwNiBTYWx0ZWRfXyxa6mk/eVEvF Cc0prlkmHuxSx2FZCNZSitHX2LtpupUyhpDO9qQM95M6/8xd2XY7mqtTYAP0d7K9P2w6CPiFoTF 8TNFu98e/nPSmkFvr/KwvnCLwewnCDWQPgjY4gO1r1aG7foWLV1y41oNxv4dyH+jQjvJWwj/dBv rWpH/X21SeurzzdAdcKmDUEWJacCuntXgegUG9cDYqqPiQ93hn0y9tTVTAa+3SBNdo9GdBQtHlH fQK/Gqi6f8yUCEHszsMTthjqb2WYp0yFT0ptqAx0kPanbSRSefWILZN3ciIhe02NDP6b+RqYLay OXsOYsES6jAiVM0EQ4A8PB4Fs/czcWQL0TKK7ZG31TfU7TAwmEPAMbtf/28N0WXd8HNA6N/joen ZYjF+WCG/n4uVutbEXRvV1vt8uAta9q6s7rx73wdBrEmtz/rKz5wmhwfNZVS2XXZJBhH1qkz X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-06-02_05,2025-05-30_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 lowpriorityscore=0 suspectscore=0 spamscore=0 malwarescore=0 clxscore=1015 mlxscore=0 impostorscore=0 priorityscore=1501 adultscore=0 bulkscore=0 phishscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505160000 definitions=main-2506020106 On 28/05/25 7:18 pm, Aditya Bodkhe wrote: > From: Aditya Bodkhe > > commit a1be9ccc57f0 ("function_graph: Support recording and printing the > return value of function") introduced support for function graph return > value tracing. > > Additionally, commit a3ed4157b7d8 ("fgraph: Replace fgraph_ret_regs with > ftrace_regs") further refactored and optimized the implementation, > making `struct fgraph_ret_regs` unnecessary. > > This patch enables the above modifications for powerpc64, ensuring that > function graph return value tracing is available on this architecture. > > After this patch, v6.14+ kernel can also be built with FPROBE on powerpc > but there are a few other build and runtime dependencies for FPROBE to > work properly. The next patch addresses them. > > Signed-off-by: Aditya Bodkhe Except for a couple of minor nits below.. Reviewed-by: Hari Bathini > --- > arch/powerpc/Kconfig | 1 + > arch/powerpc/include/asm/ftrace.h | 15 +++++++++ > arch/powerpc/kernel/trace/ftrace_entry.S | 41 ++++++++++++++---------- > 3 files changed, 40 insertions(+), 17 deletions(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index c3e0cc83f120..9163521bc4b9 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -250,6 +250,7 @@ config PPC > select HAVE_FUNCTION_ARG_ACCESS_API > select HAVE_FUNCTION_DESCRIPTORS if PPC64_ELF_ABI_V1 > select HAVE_FUNCTION_ERROR_INJECTION > + select HAVE_FUNCTION_GRAPH_FREGS > select HAVE_FUNCTION_GRAPH_TRACER > select HAVE_FUNCTION_TRACER if !COMPILE_TEST && (PPC64 || (PPC32 && CC_IS_GCC)) > select HAVE_GCC_PLUGINS if GCC_VERSION >= 50200 # plugin support on gcc <= 5.1 is buggy on PPC > diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h > index 82da7c7a1d12..6ffc9c9cf4e3 100644 > --- a/arch/powerpc/include/asm/ftrace.h > +++ b/arch/powerpc/include/asm/ftrace.h > @@ -50,6 +50,21 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs * > asm volatile("mfmsr %0" : "=r" ((_regs)->msr)); \ > } while (0) > > +#undef ftrace_regs_get_return_value > +static __always_inline unsigned long > +ftrace_regs_get_return_value(const struct ftrace_regs *fregs) > +{ > + return arch_ftrace_regs(fregs)->regs.gpr[3]; > +} > +#define ftrace_regs_get_return_value ftrace_regs_get_return_value > + > +#undef ftrace_regs_get_frame_pointer > +static __always_inline unsigned long > +ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs) > +{ > + return arch_ftrace_regs(fregs)->regs.gpr[1]; > +} > + > static __always_inline void > ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, > unsigned long ip) > diff --git a/arch/powerpc/kernel/trace/ftrace_entry.S b/arch/powerpc/kernel/trace/ftrace_entry.S > index 3565c67fc638..eafbfb7584ed 100644 > --- a/arch/powerpc/kernel/trace/ftrace_entry.S > +++ b/arch/powerpc/kernel/trace/ftrace_entry.S > @@ -409,23 +409,30 @@ EXPORT_SYMBOL(_mcount) > _GLOBAL(return_to_handler) > /* need to save return values */ > #ifdef CONFIG_PPC64 > - std r4, -32(r1) > - std r3, -24(r1) > + stdu r1, -SWITCH_FRAME_SIZE(r1) > + std r4, GPR4(r1) > + std r3, GPR3(r1) > + /* Save previous stack pointer (r1) */ Please use tab instead of " " before the comment. > + addi r3, r1, SWITCH_FRAME_SIZE > + std r3, GPR1(r1) > /* save TOC */ > - std r2, -16(r1) > - std r31, -8(r1) > + std r2, 24(r1) > + std r31, 32(r1) > mr r31, r1 > - stdu r1, -112(r1) > - > + /* pass ftrace_regs/pt_regs to ftrace_return_to_handler */ > + addi r3, r1, STACK_INT_FRAME_REGS Have a newline here > /* > * We might be called from a module. > * Switch to our TOC to run inside the core kernel. > */ > LOAD_PACA_TOC() > #else > - stwu r1, -16(r1) > - stw r3, 8(r1) > - stw r4, 12(r1) > + stwu r1, -SWITCH_FRAME_SIZE(r1) > + stw r4, GPR4(r1) > + stw r3, GPR3(r1) > + addi r3, r1, SWITCH_FRAME_SIZE > + stw r3, GPR1(r1) > + addi r3, r1, STACK_INT_FRAME_REGS > #endif > > bl ftrace_return_to_handler > @@ -435,15 +442,15 @@ _GLOBAL(return_to_handler) > mtlr r3 > > #ifdef CONFIG_PPC64 > - ld r1, 0(r1) > - ld r4, -32(r1) > - ld r3, -24(r1) > - ld r2, -16(r1) > - ld r31, -8(r1) > + ld r4, GPR4(r1) > + ld r3, GPR3(r1) > + ld r2, 24(r1) > + ld r31, 32(r1) > + ld r1, 0(r1) > #else > - lwz r3, 8(r1) > - lwz r4, 12(r1) > - addi r1, r1, 16 > + lwz r3, GPR3(r1) > + lwz r4, GPR4(r1) > + addi r1, r1, SWITCH_FRAME_SIZE > #endif > > /* Jump back to real return address */ - Hari