Re: [PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot

2024-03-17 Thread Michael Ellerman 
Benjamin Gray  writes:
> On Mon, 2024-03-18 at 08:38 +1100, Benjamin Gray wrote:
>> On Fri, 2024-03-15 at 07:14 +, Christophe Leroy wrote:
>> > Le 15/03/2024 à 03:57, Benjamin Gray a écrit :
>> > > diff --git a/arch/powerpc/lib/test-code-patching.c
>> > > b/arch/powerpc/lib/test-code-patching.c
>> > > index c44823292f73..35a3756272df 100644
>> > > --- a/arch/powerpc/lib/test-code-patching.c
>> > > +++ b/arch/powerpc/lib/test-code-patching.c
>> > > @@ -347,6 +347,97 @@ static void __init
>> > > test_prefixed_patching(void)
>> > >      check(!memcmp(iptr, expected, sizeof(expected)));
>> > >   }
>> > >   
>> > > +static void __init test_multi_instruction_patching(void)
>> > > +{
>> > > +u32 code[256];
>> > 
>> > Build failure:
>> > 
>> >    CC  arch/powerpc/lib/test-code-patching.o
>> > arch/powerpc/lib/test-code-patching.c: In function 
>> > 'test_multi_instruction_patching':
>> > arch/powerpc/lib/test-code-patching.c:439:1: error: the frame size
>> > of
>> > 1040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
>> >    439 | }
>> >    | ^
>> > cc1: all warnings being treated as errors
>> > make[4]: *** [scripts/Makefile.build:243: 
>> > arch/powerpc/lib/test-code-patching.o] Error 1
>> > 
>> > 
>> > I have to avoid big arrays on the stack.
>> 
>> All good, I can do that.
>> 
>> I do run my patches through a couple of 32-bit configs, but I didn't
>> see this error. Is this a standard config I should be testing with?
>
> Specifically pmac32_defconfig and ppc44x_defconfig

Both of those have CONFIG_FRAME_WARN=1024, so should have caught this.

But neither have CONFIG_CODE_PATCHING_SELFTEST=y, so I suspect that's
why you didn't see it.

I recommend ppc32_allmodconfig.

cheers

Re: [PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot

2024-03-17 Thread Benjamin Gray 
 
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On Mon, 2024-03-18 at 08:38 +1100, Benjamin Gray wrote:
> On Fri, 2024-03-15 at 07:14 +, Christophe Leroy wrote:
> >=20
> >=20
> > Le 15/03/2024 =C3=A0 03:57, Benjamin Gray a =C3=A9crit=C2=A0:
> > > patch_instructions() introduces new behaviour with a couple of
> > > variations. Test each case of
> > >=20
> > > =C2=A0=C2=A0 * a repeated 32-bit instruction,
> > > =C2=A0=C2=A0 * a repeated 64-bit instruction (ppc64), and
> > > =C2=A0=C2=A0 * a copied sequence of instructions
> > >=20
> > > for both on a single page and when it crosses a page boundary.
> > >=20
> > > Signed-off-by: Benjamin Gray 
> > > ---
> > > =C2=A0 arch/powerpc/lib/test-code-patching.c | 92
> > > +++
> > > =C2=A0 1 file changed, 92 insertions(+)
> > >=20
> > > diff --git a/arch/powerpc/lib/test-code-patching.c
> > > b/arch/powerpc/lib/test-code-patching.c
> > > index c44823292f73..35a3756272df 100644
> > > --- a/arch/powerpc/lib/test-code-patching.c
> > > +++ b/arch/powerpc/lib/test-code-patching.c
> > > @@ -347,6 +347,97 @@ static void __init
> > > test_prefixed_patching(void)
> > > =C2=A0=C2=A0  check(!memcmp(iptr, expected, sizeof(expected)));
> > > =C2=A0 }
> > > =C2=A0=20
> > > +static void __init test_multi_instruction_patching(void)
> > > +{
> > > + u32 code[256];
> >=20
> > Build failure:
> >=20
> > =C2=A0=C2=A0 CC=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 arch/powerpc/lib/test-cod=
e-patching.o
> > arch/powerpc/lib/test-code-patching.c: In function=20
> > 'test_multi_instruction_patching':
> > arch/powerpc/lib/test-code-patching.c:439:1: error: the frame size
> > of
> > 1040 bytes is larger than 1024 bytes [-Werror=3Dframe-larger-than=3D]
> > =C2=A0=C2=A0 439 | }
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 | ^
> > cc1: all warnings being treated as errors
> > make[4]: *** [scripts/Makefile.build:243:=20
> > arch/powerpc/lib/test-code-patching.o] Error 1
> >=20
> >=20
> > I have to avoid big arrays on the stack.
>=20
> All good, I can do that.
>=20
> I do run my patches through a couple of 32-bit configs, but I didn't
> see this error. Is this a standard config I should be testing with?
>=20

Specifically I build pmac32_defconfig and ppc44x_defconfig

Re: [PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot

2024-03-17 Thread Benjamin Gray 
On Mon, 2024-03-18 at 08:38 +1100, Benjamin Gray wrote:
> On Fri, 2024-03-15 at 07:14 +, Christophe Leroy wrote:
> > 
> > 
> > Le 15/03/2024 à 03:57, Benjamin Gray a écrit :
> > > patch_instructions() introduces new behaviour with a couple of
> > > variations. Test each case of
> > > 
> > >    * a repeated 32-bit instruction,
> > >    * a repeated 64-bit instruction (ppc64), and
> > >    * a copied sequence of instructions
> > > 
> > > for both on a single page and when it crosses a page boundary.
> > > 
> > > Signed-off-by: Benjamin Gray 
> > > ---
> > >   arch/powerpc/lib/test-code-patching.c | 92
> > > +++
> > >   1 file changed, 92 insertions(+)
> > > 
> > > diff --git a/arch/powerpc/lib/test-code-patching.c
> > > b/arch/powerpc/lib/test-code-patching.c
> > > index c44823292f73..35a3756272df 100644
> > > --- a/arch/powerpc/lib/test-code-patching.c
> > > +++ b/arch/powerpc/lib/test-code-patching.c
> > > @@ -347,6 +347,97 @@ static void __init
> > > test_prefixed_patching(void)
> > >   check(!memcmp(iptr, expected, sizeof(expected)));
> > >   }
> > >   
> > > +static void __init test_multi_instruction_patching(void)
> > > +{
> > > + u32 code[256];
> > 
> > Build failure:
> > 
> >    CC  arch/powerpc/lib/test-code-patching.o
> > arch/powerpc/lib/test-code-patching.c: In function 
> > 'test_multi_instruction_patching':
> > arch/powerpc/lib/test-code-patching.c:439:1: error: the frame size
> > of
> > 1040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
> >    439 | }
> >    | ^
> > cc1: all warnings being treated as errors
> > make[4]: *** [scripts/Makefile.build:243: 
> > arch/powerpc/lib/test-code-patching.o] Error 1
> > 
> > 
> > I have to avoid big arrays on the stack.
> 
> All good, I can do that.
> 
> I do run my patches through a couple of 32-bit configs, but I didn't
> see this error. Is this a standard config I should be testing with?

Specifically pmac32_defconfig and ppc44x_defconfig

Re: [PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot

2024-03-17 Thread Benjamin Gray 
On Fri, 2024-03-15 at 07:14 +, Christophe Leroy wrote:
> 
> 
> Le 15/03/2024 à 03:57, Benjamin Gray a écrit :
> > patch_instructions() introduces new behaviour with a couple of
> > variations. Test each case of
> > 
> >    * a repeated 32-bit instruction,
> >    * a repeated 64-bit instruction (ppc64), and
> >    * a copied sequence of instructions
> > 
> > for both on a single page and when it crosses a page boundary.
> > 
> > Signed-off-by: Benjamin Gray 
> > ---
> >   arch/powerpc/lib/test-code-patching.c | 92
> > +++
> >   1 file changed, 92 insertions(+)
> > 
> > diff --git a/arch/powerpc/lib/test-code-patching.c
> > b/arch/powerpc/lib/test-code-patching.c
> > index c44823292f73..35a3756272df 100644
> > --- a/arch/powerpc/lib/test-code-patching.c
> > +++ b/arch/powerpc/lib/test-code-patching.c
> > @@ -347,6 +347,97 @@ static void __init
> > test_prefixed_patching(void)
> >     check(!memcmp(iptr, expected, sizeof(expected)));
> >   }
> >   
> > +static void __init test_multi_instruction_patching(void)
> > +{
> > +   u32 code[256];
> 
> Build failure:
> 
>    CC  arch/powerpc/lib/test-code-patching.o
> arch/powerpc/lib/test-code-patching.c: In function 
> 'test_multi_instruction_patching':
> arch/powerpc/lib/test-code-patching.c:439:1: error: the frame size of
> 1040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
>    439 | }
>    | ^
> cc1: all warnings being treated as errors
> make[4]: *** [scripts/Makefile.build:243: 
> arch/powerpc/lib/test-code-patching.o] Error 1
> 
> 
> I have to avoid big arrays on the stack.

All good, I can do that.

I do run my patches through a couple of 32-bit configs, but I didn't
see this error. Is this a standard config I should be testing with?

> 
> 
> > +   void *buf;
> > +   u32 *addr32;
> > +   u64 *addr64;
> > +   ppc_inst_t inst64 = ppc_inst_prefix(OP_PREFIX << 26 | 3UL
> > << 24, PPC_RAW_TRAP());
> > +   u32 inst32 = PPC_RAW_NOP();
> > +
> > +   buf = vzalloc(PAGE_SIZE * 8);
> > +   check(buf);
> > +   if (!buf)
> > +   return;
> > +
> > +   /* Test single page 32-bit repeated instruction */
> > +   addr32 = buf + PAGE_SIZE;
> > +   check(!patch_instructions(addr32 + 1, , 12, true));
> > +
> > +   check(addr32[0] == 0);
> > +   check(addr32[1] == inst32);
> > +   check(addr32[2] == inst32);
> > +   check(addr32[3] == inst32);
> > +   check(addr32[4] == 0);
> > +
> > +   /* Test single page 64-bit repeated instruction */
> > +   if (IS_ENABLED(CONFIG_PPC64)) {
> > +   check(ppc_inst_prefixed(inst64));
> > +
> > +   addr64 = buf + PAGE_SIZE * 2;
> > +   ppc_inst_write(code, inst64);
> > +   check(!patch_instructions((u32 *)(addr64 + 1),
> > code, 24, true));
> > +
> > +   check(addr64[0] == 0);
> > +   check(ppc_inst_equal(ppc_inst_read((u32
> > *)[1]), inst64));
> > +   check(ppc_inst_equal(ppc_inst_read((u32
> > *)[2]), inst64));
> > +   check(ppc_inst_equal(ppc_inst_read((u32
> > *)[3]), inst64));
> > +   check(addr64[4] == 0);
> > +   }
> > +
> > +   /* Test single page memcpy */
> > +   addr32 = buf + PAGE_SIZE * 3;
> > +
> > +   for (int i = 0; i < ARRAY_SIZE(code); i++)
> > +   code[i] = i + 1;
> > +
> > +   check(!patch_instructions(addr32 + 1, code, sizeof(code),
> > false));
> > +
> > +   check(addr32[0] == 0);
> > +   check(!memcmp([1], code, sizeof(code)));
> > +   check(addr32[ARRAY_SIZE(code) + 1] == 0);
> > +
> > +   /* Test multipage 32-bit repeated instruction */
> > +   addr32 = buf + PAGE_SIZE * 4 - 8;
> > +   check(!patch_instructions(addr32 + 1, , 12, true));
> > +
> > +   check(addr32[0] == 0);
> > +   check(addr32[1] == inst32);
> > +   check(addr32[2] == inst32);
> > +   check(addr32[3] == inst32);
> > +   check(addr32[4] == 0);
> > +
> > +   /* Test multipage 64-bit repeated instruction */
> > +   if (IS_ENABLED(CONFIG_PPC64)) {
> > +   check(ppc_inst_prefixed(inst64));
> > +
> > +   addr64 = buf + PAGE_SIZE * 5 - 8;
> > +   ppc_inst_write(code, inst64);
> > +   check(!patch_instructions((u32 *)(addr64 + 1),
> > code, 24, true));
> > +
> > +   check(addr64[0] == 0);
> > +   check(ppc_inst_equal(ppc_inst_read((u32
> > *)[1]), inst64));
> > +   check(ppc_inst_equal(ppc_inst_read((u32
> > *)[2]), inst64));
> > +   check(ppc_inst_equal(ppc_inst_read((u32
> > *)[3]), inst64));
> > +   check(addr64[4] == 0);
> > +   }
> > +
> > +   /* Test multipage memcpy */
> > +   addr32 = buf + PAGE_SIZE * 6 - 12;
> > +
> > +   for (int i = 0; i < ARRAY_SIZE(code); i++)
> > +   code[i] = i + 1;
> > +
> > +   check(!patch_instructions(addr32 + 1, code, sizeof(code),
> > false));
> > +
> > +   check(addr32[0] == 0);
> > +   check(!memcmp([1], code, sizeof(code)));
> > +   check(addr32[ARRAY_SIZE(code) + 1] == 0);
> > +
> > +   vfree(buf);
> > +}
> > +
> >   static int __init test_code_patching(void)
> >   {
> >     pr_info("Running code

Re: [PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot

2024-03-15 Thread Christophe Leroy 


Le 15/03/2024 à 03:57, Benjamin Gray a écrit :
> patch_instructions() introduces new behaviour with a couple of
> variations. Test each case of
> 
>* a repeated 32-bit instruction,
>* a repeated 64-bit instruction (ppc64), and
>* a copied sequence of instructions
> 
> for both on a single page and when it crosses a page boundary.
> 
> Signed-off-by: Benjamin Gray 
> ---
>   arch/powerpc/lib/test-code-patching.c | 92 +++
>   1 file changed, 92 insertions(+)
> 
> diff --git a/arch/powerpc/lib/test-code-patching.c 
> b/arch/powerpc/lib/test-code-patching.c
> index c44823292f73..35a3756272df 100644
> --- a/arch/powerpc/lib/test-code-patching.c
> +++ b/arch/powerpc/lib/test-code-patching.c
> @@ -347,6 +347,97 @@ static void __init test_prefixed_patching(void)
>   check(!memcmp(iptr, expected, sizeof(expected)));
>   }
>   
> +static void __init test_multi_instruction_patching(void)
> +{
> + u32 code[256];

Build failure:

   CC  arch/powerpc/lib/test-code-patching.o
arch/powerpc/lib/test-code-patching.c: In function 
'test_multi_instruction_patching':
arch/powerpc/lib/test-code-patching.c:439:1: error: the frame size of 
1040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
   439 | }
   | ^
cc1: all warnings being treated as errors
make[4]: *** [scripts/Makefile.build:243: 
arch/powerpc/lib/test-code-patching.o] Error 1


I have to avoid big arrays on the stack.


> + void *buf;
> + u32 *addr32;
> + u64 *addr64;
> + ppc_inst_t inst64 = ppc_inst_prefix(OP_PREFIX << 26 | 3UL << 24, 
> PPC_RAW_TRAP());
> + u32 inst32 = PPC_RAW_NOP();
> +
> + buf = vzalloc(PAGE_SIZE * 8);
> + check(buf);
> + if (!buf)
> + return;
> +
> + /* Test single page 32-bit repeated instruction */
> + addr32 = buf + PAGE_SIZE;
> + check(!patch_instructions(addr32 + 1, , 12, true));
> +
> + check(addr32[0] == 0);
> + check(addr32[1] == inst32);
> + check(addr32[2] == inst32);
> + check(addr32[3] == inst32);
> + check(addr32[4] == 0);
> +
> + /* Test single page 64-bit repeated instruction */
> + if (IS_ENABLED(CONFIG_PPC64)) {
> + check(ppc_inst_prefixed(inst64));
> +
> + addr64 = buf + PAGE_SIZE * 2;
> + ppc_inst_write(code, inst64);
> + check(!patch_instructions((u32 *)(addr64 + 1), code, 24, true));
> +
> + check(addr64[0] == 0);
> + check(ppc_inst_equal(ppc_inst_read((u32 *)[1]), inst64));
> + check(ppc_inst_equal(ppc_inst_read((u32 *)[2]), inst64));
> + check(ppc_inst_equal(ppc_inst_read((u32 *)[3]), inst64));
> + check(addr64[4] == 0);
> + }
> +
> + /* Test single page memcpy */
> + addr32 = buf + PAGE_SIZE * 3;
> +
> + for (int i = 0; i < ARRAY_SIZE(code); i++)
> + code[i] = i + 1;
> +
> + check(!patch_instructions(addr32 + 1, code, sizeof(code), false));
> +
> + check(addr32[0] == 0);
> + check(!memcmp([1], code, sizeof(code)));
> + check(addr32[ARRAY_SIZE(code) + 1] == 0);
> +
> + /* Test multipage 32-bit repeated instruction */
> + addr32 = buf + PAGE_SIZE * 4 - 8;
> + check(!patch_instructions(addr32 + 1, , 12, true));
> +
> + check(addr32[0] == 0);
> + check(addr32[1] == inst32);
> + check(addr32[2] == inst32);
> + check(addr32[3] == inst32);
> + check(addr32[4] == 0);
> +
> + /* Test multipage 64-bit repeated instruction */
> + if (IS_ENABLED(CONFIG_PPC64)) {
> + check(ppc_inst_prefixed(inst64));
> +
> + addr64 = buf + PAGE_SIZE * 5 - 8;
> + ppc_inst_write(code, inst64);
> + check(!patch_instructions((u32 *)(addr64 + 1), code, 24, true));
> +
> + check(addr64[0] == 0);
> + check(ppc_inst_equal(ppc_inst_read((u32 *)[1]), inst64));
> + check(ppc_inst_equal(ppc_inst_read((u32 *)[2]), inst64));
> + check(ppc_inst_equal(ppc_inst_read((u32 *)[3]), inst64));
> + check(addr64[4] == 0);
> + }
> +
> + /* Test multipage memcpy */
> + addr32 = buf + PAGE_SIZE * 6 - 12;
> +
> + for (int i = 0; i < ARRAY_SIZE(code); i++)
> + code[i] = i + 1;
> +
> + check(!patch_instructions(addr32 + 1, code, sizeof(code), false));
> +
> + check(addr32[0] == 0);
> + check(!memcmp([1], code, sizeof(code)));
> + check(addr32[ARRAY_SIZE(code) + 1] == 0);
> +
> + vfree(buf);
> +}
> +
>   static int __init test_code_patching(void)
>   {
>   pr_info("Running code patching self-tests ...\n");
> @@ -356,6 +447,7 @@ static int __init test_code_patching(void)
>   test_create_function_call();
>   test_translate_branch();
>   test_prefixed_patching();
> + test_multi_instruction_patching();
>   
>   return 0;
>   }

[PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot

2024-03-14 Thread Benjamin Gray 
patch_instructions() introduces new behaviour with a couple of
variations. Test each case of

  * a repeated 32-bit instruction,
  * a repeated 64-bit instruction (ppc64), and
  * a copied sequence of instructions

for both on a single page and when it crosses a page boundary.

Signed-off-by: Benjamin Gray 
---
 arch/powerpc/lib/test-code-patching.c | 92 +++
 1 file changed, 92 insertions(+)

diff --git a/arch/powerpc/lib/test-code-patching.c 
b/arch/powerpc/lib/test-code-patching.c
index c44823292f73..35a3756272df 100644
--- a/arch/powerpc/lib/test-code-patching.c
+++ b/arch/powerpc/lib/test-code-patching.c
@@ -347,6 +347,97 @@ static void __init test_prefixed_patching(void)
check(!memcmp(iptr, expected, sizeof(expected)));
 }
 
+static void __init test_multi_instruction_patching(void)
+{
+   u32 code[256];
+   void *buf;
+   u32 *addr32;
+   u64 *addr64;
+   ppc_inst_t inst64 = ppc_inst_prefix(OP_PREFIX << 26 | 3UL << 24, 
PPC_RAW_TRAP());
+   u32 inst32 = PPC_RAW_NOP();
+
+   buf = vzalloc(PAGE_SIZE * 8);
+   check(buf);
+   if (!buf)
+   return;
+
+   /* Test single page 32-bit repeated instruction */
+   addr32 = buf + PAGE_SIZE;
+   check(!patch_instructions(addr32 + 1, , 12, true));
+
+   check(addr32[0] == 0);
+   check(addr32[1] == inst32);
+   check(addr32[2] == inst32);
+   check(addr32[3] == inst32);
+   check(addr32[4] == 0);
+
+   /* Test single page 64-bit repeated instruction */
+   if (IS_ENABLED(CONFIG_PPC64)) {
+   check(ppc_inst_prefixed(inst64));
+
+   addr64 = buf + PAGE_SIZE * 2;
+   ppc_inst_write(code, inst64);
+   check(!patch_instructions((u32 *)(addr64 + 1), code, 24, true));
+
+   check(addr64[0] == 0);
+   check(ppc_inst_equal(ppc_inst_read((u32 *)[1]), inst64));
+   check(ppc_inst_equal(ppc_inst_read((u32 *)[2]), inst64));
+   check(ppc_inst_equal(ppc_inst_read((u32 *)[3]), inst64));
+   check(addr64[4] == 0);
+   }
+
+   /* Test single page memcpy */
+   addr32 = buf + PAGE_SIZE * 3;
+
+   for (int i = 0; i < ARRAY_SIZE(code); i++)
+   code[i] = i + 1;
+
+   check(!patch_instructions(addr32 + 1, code, sizeof(code), false));
+
+   check(addr32[0] == 0);
+   check(!memcmp([1], code, sizeof(code)));
+   check(addr32[ARRAY_SIZE(code) + 1] == 0);
+
+   /* Test multipage 32-bit repeated instruction */
+   addr32 = buf + PAGE_SIZE * 4 - 8;
+   check(!patch_instructions(addr32 + 1, , 12, true));
+
+   check(addr32[0] == 0);
+   check(addr32[1] == inst32);
+   check(addr32[2] == inst32);
+   check(addr32[3] == inst32);
+   check(addr32[4] == 0);
+
+   /* Test multipage 64-bit repeated instruction */
+   if (IS_ENABLED(CONFIG_PPC64)) {
+   check(ppc_inst_prefixed(inst64));
+
+   addr64 = buf + PAGE_SIZE * 5 - 8;
+   ppc_inst_write(code, inst64);
+   check(!patch_instructions((u32 *)(addr64 + 1), code, 24, true));
+
+   check(addr64[0] == 0);
+   check(ppc_inst_equal(ppc_inst_read((u32 *)[1]), inst64));
+   check(ppc_inst_equal(ppc_inst_read((u32 *)[2]), inst64));
+   check(ppc_inst_equal(ppc_inst_read((u32 *)[3]), inst64));
+   check(addr64[4] == 0);
+   }
+
+   /* Test multipage memcpy */
+   addr32 = buf + PAGE_SIZE * 6 - 12;
+
+   for (int i = 0; i < ARRAY_SIZE(code); i++)
+   code[i] = i + 1;
+
+   check(!patch_instructions(addr32 + 1, code, sizeof(code), false));
+
+   check(addr32[0] == 0);
+   check(!memcmp([1], code, sizeof(code)));
+   check(addr32[ARRAY_SIZE(code) + 1] == 0);
+
+   vfree(buf);
+}
+
 static int __init test_code_patching(void)
 {
pr_info("Running code patching self-tests ...\n");
@@ -356,6 +447,7 @@ static int __init test_code_patching(void)
test_create_function_call();
test_translate_branch();
test_prefixed_patching();
+   test_multi_instruction_patching();
 
return 0;
 }
-- 
2.44.0