* Re: [PATCH] recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64.
[not found] <20200717143338.19302-1-gregory.herrero@oracle.com>
@ 2020-07-17 17:30 ` Steven Rostedt
[not found] ` <20200717200119.GP17377@ltoracle>
2020-07-22 16:36 ` Catalin Marinas
0 siblings, 2 replies; 4+ messages in thread
From: Steven Rostedt @ 2020-07-17 17:30 UTC (permalink / raw)
To: gregory.herrero
Cc: linux-arm-kernel, Catalin Marinas, Will Deacon, linux-kernel, stable
On Fri, 17 Jul 2020 16:33:38 +0200
gregory.herrero@oracle.com wrote:
> From: Gregory Herrero <gregory.herrero@oracle.com>
>
> Currently, if a section has a relocation to '_mcount' symbol, a new
> __mcount_loc entry will be added whatever the relocation type is.
> This is problematic when a relocation to '_mcount' is in the middle of a
> section and is not a call for ftrace use.
>
> Such relocation could be generated with below code for example:
> bool is_mcount(unsigned long addr)
> {
> return (target == (unsigned long) &_mcount);
> }
>
> With this snippet of code, ftrace will try to patch the mcount location
> generated by this code on module load and fail with:
>
> Call trace:
> ftrace_bug+0xa0/0x28c
> ftrace_process_locs+0x2f4/0x430
> ftrace_module_init+0x30/0x38
> load_module+0x14f0/0x1e78
> __do_sys_finit_module+0x100/0x11c
> __arm64_sys_finit_module+0x28/0x34
> el0_svc_common+0x88/0x194
> el0_svc_handler+0x38/0x8c
> el0_svc+0x8/0xc
> ---[ end trace d828d06b36ad9d59 ]---
> ftrace failed to modify
> [<ffffa2dbf3a3a41c>] 0xffffa2dbf3a3a41c
> actual: 66:a9:3c:90
> Initializing ftrace call sites
> ftrace record flags: 2000000
> (0)
> expected tramp: ffffa2dc6cf66724
>
> So Limit the relocation type to R_AARCH64_CALL26 as in perl version of
> recordmcount.
>
I'd rather have this go through the arm64 tree, as they can test it
better than I can.
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-- Steve
> Fixes: ed60453fa8f8 ("ARM: 6511/1: ftrace: add ARM support for C version of recordmcount")
> Signed-off-by: Gregory Herrero <gregory.herrero@oracle.com>
> ---
> scripts/recordmcount.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
> index 7225107a9aaf..e59022b3f125 100644
> --- a/scripts/recordmcount.c
> +++ b/scripts/recordmcount.c
> @@ -434,6 +434,11 @@ static int arm_is_fake_mcount(Elf32_Rel const *rp)
> return 1;
> }
>
> +static int arm64_is_fake_mcount(Elf64_Rel const *rp)
> +{
> + return ELF64_R_TYPE(w(rp->r_info)) != R_AARCH64_CALL26;
> +}
> +
> /* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
> * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
> * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
> @@ -547,6 +552,7 @@ static int do_file(char const *const fname)
> make_nop = make_nop_arm64;
> rel_type_nop = R_AARCH64_NONE;
> ideal_nop = ideal_nop4_arm64;
> + is_fake_mcount64 = arm64_is_fake_mcount;
> break;
> case EM_IA_64: reltype = R_IA64_IMM64; break;
> case EM_MIPS: /* reltype: e_class */ break;
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64.
[not found] ` <20200717200119.GP17377@ltoracle>
@ 2020-07-17 20:15 ` Steven Rostedt
0 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2020-07-17 20:15 UTC (permalink / raw)
To: Gregory Herrero
Cc: linux-arm-kernel, Catalin Marinas, Will Deacon, linux-kernel, stable
On Fri, 17 Jul 2020 22:01:19 +0200
Gregory Herrero <gregory.herrero@oracle.com> wrote:
> Thanks Steve.
> Should I send a V2 to add 'Cc: stable@vger.kernel.org' in the commit
> description or can someone take care of it when adding the commit to
> the tree?
If I was taking it, I would simply add the Cc: stable@vger.kernel.org
to the commit log, and no resend would be needed.
It's up to the ARM64 maintainers to decide in this case.
Cheers,
-- Steve
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64.
2020-07-17 17:30 ` [PATCH] recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64 Steven Rostedt
[not found] ` <20200717200119.GP17377@ltoracle>
@ 2020-07-22 16:36 ` Catalin Marinas
2020-07-22 18:50 ` Gregory Herrero
1 sibling, 1 reply; 4+ messages in thread
From: Catalin Marinas @ 2020-07-22 16:36 UTC (permalink / raw)
To: Steven Rostedt
Cc: linux-arm-kernel, gregory.herrero, Will Deacon, linux-kernel, stable
On Fri, Jul 17, 2020 at 01:30:03PM -0400, Steven Rostedt wrote:
> On Fri, 17 Jul 2020 16:33:38 +0200
> gregory.herrero@oracle.com wrote:
> > From: Gregory Herrero <gregory.herrero@oracle.com>
> > Currently, if a section has a relocation to '_mcount' symbol, a new
> > __mcount_loc entry will be added whatever the relocation type is.
> > This is problematic when a relocation to '_mcount' is in the middle of a
> > section and is not a call for ftrace use.
> >
> > Such relocation could be generated with below code for example:
> > bool is_mcount(unsigned long addr)
> > {
> > return (target == (unsigned long) &_mcount);
> > }
> >
> > With this snippet of code, ftrace will try to patch the mcount location
> > generated by this code on module load and fail with:
> >
> > Call trace:
> > ftrace_bug+0xa0/0x28c
> > ftrace_process_locs+0x2f4/0x430
> > ftrace_module_init+0x30/0x38
> > load_module+0x14f0/0x1e78
> > __do_sys_finit_module+0x100/0x11c
> > __arm64_sys_finit_module+0x28/0x34
> > el0_svc_common+0x88/0x194
> > el0_svc_handler+0x38/0x8c
> > el0_svc+0x8/0xc
> > ---[ end trace d828d06b36ad9d59 ]---
> > ftrace failed to modify
> > [<ffffa2dbf3a3a41c>] 0xffffa2dbf3a3a41c
> > actual: 66:a9:3c:90
> > Initializing ftrace call sites
> > ftrace record flags: 2000000
> > (0)
> > expected tramp: ffffa2dc6cf66724
> >
> > So Limit the relocation type to R_AARCH64_CALL26 as in perl version of
> > recordmcount.
>
> I'd rather have this go through the arm64 tree, as they can test it
> better than I can.
>
> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Thanks Steve.
> > Fixes: ed60453fa8f8 ("ARM: 6511/1: ftrace: add ARM support for C version of recordmcount")
This Fixes tag looks wrong. The above commit was for arm32.
--
Catalin
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64.
2020-07-22 16:36 ` Catalin Marinas
@ 2020-07-22 18:50 ` Gregory Herrero
0 siblings, 0 replies; 4+ messages in thread
From: Gregory Herrero @ 2020-07-22 18:50 UTC (permalink / raw)
To: Catalin Marinas
Cc: linux-arm-kernel, stable, Will Deacon, linux-kernel, Steven Rostedt
On Wed, Jul 22, 2020 at 05:36:50PM +0100, Catalin Marinas wrote:
> On Fri, Jul 17, 2020 at 01:30:03PM -0400, Steven Rostedt wrote:
> > On Fri, 17 Jul 2020 16:33:38 +0200
> > gregory.herrero@oracle.com wrote:
> > > From: Gregory Herrero <gregory.herrero@oracle.com>
> > > Currently, if a section has a relocation to '_mcount' symbol, a new
> > > __mcount_loc entry will be added whatever the relocation type is.
> > > This is problematic when a relocation to '_mcount' is in the middle of a
> > > section and is not a call for ftrace use.
> > >
> > > Such relocation could be generated with below code for example:
> > > bool is_mcount(unsigned long addr)
> > > {
> > > return (target == (unsigned long) &_mcount);
> > > }
> > >
> > > With this snippet of code, ftrace will try to patch the mcount location
> > > generated by this code on module load and fail with:
> > >
> > > Call trace:
> > > ftrace_bug+0xa0/0x28c
> > > ftrace_process_locs+0x2f4/0x430
> > > ftrace_module_init+0x30/0x38
> > > load_module+0x14f0/0x1e78
> > > __do_sys_finit_module+0x100/0x11c
> > > __arm64_sys_finit_module+0x28/0x34
> > > el0_svc_common+0x88/0x194
> > > el0_svc_handler+0x38/0x8c
> > > el0_svc+0x8/0xc
> > > ---[ end trace d828d06b36ad9d59 ]---
> > > ftrace failed to modify
> > > [<ffffa2dbf3a3a41c>] 0xffffa2dbf3a3a41c
> > > actual: 66:a9:3c:90
> > > Initializing ftrace call sites
> > > ftrace record flags: 2000000
> > > (0)
> > > expected tramp: ffffa2dc6cf66724
> > >
> > > So Limit the relocation type to R_AARCH64_CALL26 as in perl version of
> > > recordmcount.
> >
> > I'd rather have this go through the arm64 tree, as they can test it
> > better than I can.
> >
> > Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
>
> Thanks Steve.
>
> > > Fixes: ed60453fa8f8 ("ARM: 6511/1: ftrace: add ARM support for C version of recordmcount")
>
> This Fixes tag looks wrong. The above commit was for arm32.
>
Thanks for catching this.
It should be as below instead:
Fixes: af64d2aa872a ("ftrace: Add arm64 support to recordmcount")
Should I send a V2?
Thanks,
Greg
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2020-07-17 17:30 ` [PATCH] recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64 Steven Rostedt
[not found] ` <20200717200119.GP17377@ltoracle>
2020-07-17 20:15 ` Steven Rostedt
2020-07-22 16:36 ` Catalin Marinas
2020-07-22 18:50 ` Gregory Herrero
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