* [PATCH] powerpc/module_64: Fix livepatching for RO modules
@ 2021-11-23 8:15 Russell Currey
2021-12-07 14:44 ` Joe Lawrence
2021-12-15 0:51 ` Michael Ellerman
0 siblings, 2 replies; 10+ messages in thread
From: Russell Currey @ 2021-11-23 8:15 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Joe Lawrence, jniethe5, Russell Currey, naveen.n.rao
Livepatching a loaded module involves applying relocations through
apply_relocate_add(), which attempts to write to read-only memory when
CONFIG_STRICT_MODULE_RWX=y. Work around this by performing these
writes through the text poke area by using patch_instruction().
R_PPC_REL24 is the only relocation type generated by the kpatch-build
userspace tool or klp-convert kernel tree that I observed applying a
relocation to a post-init module.
A more comprehensive solution is planned, but using patch_instruction()
for R_PPC_REL24 on should serve as a sufficient fix.
This does have a performance impact, I observed ~15% overhead in
module_load() on POWER8 bare metal with checksum verification off.
Fixes: c35717c71e98 ("powerpc: Set ARCH_HAS_STRICT_MODULE_RWX")
Cc: stable@vger.kernel.org # v5.14+
Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Russell Currey <ruscur@russell.cc>
---
Intended to be a minimal fix that can go to stable.
arch/powerpc/kernel/module_64.c | 30 ++++++++++++++++++++++--------
1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 6baa676e7cb6..c25ef36c3ef4 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -422,11 +422,16 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
const char *name)
{
long reladdr;
+ func_desc_t desc;
+ int i;
if (is_mprofile_ftrace_call(name))
return create_ftrace_stub(entry, addr, me);
- memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
+ for (i = 0; i < sizeof(ppc64_stub_insns) / sizeof(u32); i++) {
+ patch_instruction(&entry->jump[i],
+ ppc_inst(ppc64_stub_insns[i]));
+ }
/* Stub uses address relative to r2. */
reladdr = (unsigned long)entry - my_r2(sechdrs, me);
@@ -437,10 +442,19 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
}
pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
- entry->jump[0] |= PPC_HA(reladdr);
- entry->jump[1] |= PPC_LO(reladdr);
- entry->funcdata = func_desc(addr);
- entry->magic = STUB_MAGIC;
+ patch_instruction(&entry->jump[0],
+ ppc_inst(entry->jump[0] | PPC_HA(reladdr)));
+ patch_instruction(&entry->jump[1],
+ ppc_inst(entry->jump[1] | PPC_LO(reladdr)));
+
+ // func_desc_t is 8 bytes if ABIv2, else 16 bytes
+ desc = func_desc(addr);
+ for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
+ patch_instruction(((u32 *)&entry->funcdata) + i,
+ ppc_inst(((u32 *)(&desc))[i]));
+ }
+
+ patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC));
return 1;
}
@@ -496,7 +510,7 @@ static int restore_r2(const char *name, u32 *instruction, struct module *me)
return 0;
}
/* ld r2,R2_STACK_OFFSET(r1) */
- *instruction = PPC_INST_LD_TOC;
+ patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
return 1;
}
@@ -636,9 +650,9 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
}
/* Only replace bits 2 through 26 */
- *(uint32_t *)location
- = (*(uint32_t *)location & ~0x03fffffc)
+ value = (*(uint32_t *)location & ~0x03fffffc)
| (value & 0x03fffffc);
+ patch_instruction((u32 *)location, ppc_inst(value));
break;
case R_PPC64_REL64:
--
2.34.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
2021-11-23 8:15 [PATCH] powerpc/module_64: Fix livepatching for RO modules Russell Currey
@ 2021-12-07 14:44 ` Joe Lawrence
2021-12-15 0:51 ` Michael Ellerman
1 sibling, 0 replies; 10+ messages in thread
From: Joe Lawrence @ 2021-12-07 14:44 UTC (permalink / raw)
To: Russell Currey, linuxppc-dev
Cc: jniethe5, naveen.n.rao, mpe, christophe.leroy, live-patching
On 11/23/21 3:15 AM, Russell Currey wrote:
> Livepatching a loaded module involves applying relocations through
> apply_relocate_add(), which attempts to write to read-only memory when
> CONFIG_STRICT_MODULE_RWX=y. Work around this by performing these
> writes through the text poke area by using patch_instruction().
>
> R_PPC_REL24 is the only relocation type generated by the kpatch-build
> userspace tool or klp-convert kernel tree that I observed applying a
> relocation to a post-init module.
>
> A more comprehensive solution is planned, but using patch_instruction()
> for R_PPC_REL24 on should serve as a sufficient fix.
>
> This does have a performance impact, I observed ~15% overhead in
> module_load() on POWER8 bare metal with checksum verification off.
>
> Fixes: c35717c71e98 ("powerpc: Set ARCH_HAS_STRICT_MODULE_RWX")
> Cc: stable@vger.kernel.org # v5.14+
> Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> ---
> Intended to be a minimal fix that can go to stable.
>
> arch/powerpc/kernel/module_64.c | 30 ++++++++++++++++++++++--------
> 1 file changed, 22 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
> index 6baa676e7cb6..c25ef36c3ef4 100644
> --- a/arch/powerpc/kernel/module_64.c
> +++ b/arch/powerpc/kernel/module_64.c
> @@ -422,11 +422,16 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
> const char *name)
> {
> long reladdr;
> + func_desc_t desc;
> + int i;
>
> if (is_mprofile_ftrace_call(name))
> return create_ftrace_stub(entry, addr, me);
>
> - memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
> + for (i = 0; i < sizeof(ppc64_stub_insns) / sizeof(u32); i++) {
> + patch_instruction(&entry->jump[i],
> + ppc_inst(ppc64_stub_insns[i]));
> + }
>
> /* Stub uses address relative to r2. */
> reladdr = (unsigned long)entry - my_r2(sechdrs, me);
> @@ -437,10 +442,19 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
> }
> pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
>
> - entry->jump[0] |= PPC_HA(reladdr);
> - entry->jump[1] |= PPC_LO(reladdr);
> - entry->funcdata = func_desc(addr);
> - entry->magic = STUB_MAGIC;
> + patch_instruction(&entry->jump[0],
> + ppc_inst(entry->jump[0] | PPC_HA(reladdr)));
> + patch_instruction(&entry->jump[1],
> + ppc_inst(entry->jump[1] | PPC_LO(reladdr)));
> +
> + // func_desc_t is 8 bytes if ABIv2, else 16 bytes
> + desc = func_desc(addr);
> + for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
> + patch_instruction(((u32 *)&entry->funcdata) + i,
> + ppc_inst(((u32 *)(&desc))[i]));
> + }
> +
> + patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC));
>
> return 1;
> }
> @@ -496,7 +510,7 @@ static int restore_r2(const char *name, u32 *instruction, struct module *me)
> return 0;
> }
> /* ld r2,R2_STACK_OFFSET(r1) */
> - *instruction = PPC_INST_LD_TOC;
> + patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
> return 1;
> }
>
> @@ -636,9 +650,9 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
> }
>
> /* Only replace bits 2 through 26 */
> - *(uint32_t *)location
> - = (*(uint32_t *)location & ~0x03fffffc)
> + value = (*(uint32_t *)location & ~0x03fffffc)
> | (value & 0x03fffffc);
> + patch_instruction((u32 *)location, ppc_inst(value));
> break;
>
> case R_PPC64_REL64:
>
[[ cc += livepatching list ]]
Hi Russell,
Thanks for writing a minimal fix for stable / backporting. As I
mentioned on the github issue [1], this avoided the crashes I reported
here and over on kpatch github [2]. I wasn't sure if this is the final
version for stable, but feel free to add my:
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
[1] https://github.com/linuxppc/issues/issues/375
[2] https://github.com/dynup/kpatch/issues/1228
--
Joe
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
@ 2021-12-07 14:44 ` Joe Lawrence
0 siblings, 0 replies; 10+ messages in thread
From: Joe Lawrence @ 2021-12-07 14:44 UTC (permalink / raw)
To: Russell Currey, linuxppc-dev; +Cc: live-patching, jniethe5, naveen.n.rao
On 11/23/21 3:15 AM, Russell Currey wrote:
> Livepatching a loaded module involves applying relocations through
> apply_relocate_add(), which attempts to write to read-only memory when
> CONFIG_STRICT_MODULE_RWX=y. Work around this by performing these
> writes through the text poke area by using patch_instruction().
>
> R_PPC_REL24 is the only relocation type generated by the kpatch-build
> userspace tool or klp-convert kernel tree that I observed applying a
> relocation to a post-init module.
>
> A more comprehensive solution is planned, but using patch_instruction()
> for R_PPC_REL24 on should serve as a sufficient fix.
>
> This does have a performance impact, I observed ~15% overhead in
> module_load() on POWER8 bare metal with checksum verification off.
>
> Fixes: c35717c71e98 ("powerpc: Set ARCH_HAS_STRICT_MODULE_RWX")
> Cc: stable@vger.kernel.org # v5.14+
> Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> ---
> Intended to be a minimal fix that can go to stable.
>
> arch/powerpc/kernel/module_64.c | 30 ++++++++++++++++++++++--------
> 1 file changed, 22 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
> index 6baa676e7cb6..c25ef36c3ef4 100644
> --- a/arch/powerpc/kernel/module_64.c
> +++ b/arch/powerpc/kernel/module_64.c
> @@ -422,11 +422,16 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
> const char *name)
> {
> long reladdr;
> + func_desc_t desc;
> + int i;
>
> if (is_mprofile_ftrace_call(name))
> return create_ftrace_stub(entry, addr, me);
>
> - memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
> + for (i = 0; i < sizeof(ppc64_stub_insns) / sizeof(u32); i++) {
> + patch_instruction(&entry->jump[i],
> + ppc_inst(ppc64_stub_insns[i]));
> + }
>
> /* Stub uses address relative to r2. */
> reladdr = (unsigned long)entry - my_r2(sechdrs, me);
> @@ -437,10 +442,19 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
> }
> pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
>
> - entry->jump[0] |= PPC_HA(reladdr);
> - entry->jump[1] |= PPC_LO(reladdr);
> - entry->funcdata = func_desc(addr);
> - entry->magic = STUB_MAGIC;
> + patch_instruction(&entry->jump[0],
> + ppc_inst(entry->jump[0] | PPC_HA(reladdr)));
> + patch_instruction(&entry->jump[1],
> + ppc_inst(entry->jump[1] | PPC_LO(reladdr)));
> +
> + // func_desc_t is 8 bytes if ABIv2, else 16 bytes
> + desc = func_desc(addr);
> + for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
> + patch_instruction(((u32 *)&entry->funcdata) + i,
> + ppc_inst(((u32 *)(&desc))[i]));
> + }
> +
> + patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC));
>
> return 1;
> }
> @@ -496,7 +510,7 @@ static int restore_r2(const char *name, u32 *instruction, struct module *me)
> return 0;
> }
> /* ld r2,R2_STACK_OFFSET(r1) */
> - *instruction = PPC_INST_LD_TOC;
> + patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
> return 1;
> }
>
> @@ -636,9 +650,9 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
> }
>
> /* Only replace bits 2 through 26 */
> - *(uint32_t *)location
> - = (*(uint32_t *)location & ~0x03fffffc)
> + value = (*(uint32_t *)location & ~0x03fffffc)
> | (value & 0x03fffffc);
> + patch_instruction((u32 *)location, ppc_inst(value));
> break;
>
> case R_PPC64_REL64:
>
[[ cc += livepatching list ]]
Hi Russell,
Thanks for writing a minimal fix for stable / backporting. As I
mentioned on the github issue [1], this avoided the crashes I reported
here and over on kpatch github [2]. I wasn't sure if this is the final
version for stable, but feel free to add my:
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
[1] https://github.com/linuxppc/issues/issues/375
[2] https://github.com/dynup/kpatch/issues/1228
--
Joe
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
2021-12-07 14:44 ` Joe Lawrence
@ 2021-12-08 1:51 ` Russell Currey
-1 siblings, 0 replies; 10+ messages in thread
From: Russell Currey @ 2021-12-08 1:51 UTC (permalink / raw)
To: Joe Lawrence, linuxppc-dev
Cc: jniethe5, naveen.n.rao, mpe, christophe.leroy, live-patching
On Tue, 2021-12-07 at 09:44 -0500, Joe Lawrence wrote:
> On 11/23/21 3:15 AM, Russell Currey wrote:
>
> [[ cc += livepatching list ]]
>
> Hi Russell,
>
> Thanks for writing a minimal fix for stable / backporting. As I
> mentioned on the github issue [1], this avoided the crashes I
> reported
> here and over on kpatch github [2]. I wasn't sure if this is the
> final
> version for stable, but feel free to add my:
>
> Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Thanks Joe, as per the discussions on GitHub I think we're fine to use
this patch for a fix for stable (unless there's new issues found or
additional community feedback etc).
>
> [1] https://github.com/linuxppc/issues/issues/375
> [2] https://github.com/dynup/kpatch/issues/1228
>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
@ 2021-12-08 1:51 ` Russell Currey
0 siblings, 0 replies; 10+ messages in thread
From: Russell Currey @ 2021-12-08 1:51 UTC (permalink / raw)
To: Joe Lawrence, linuxppc-dev; +Cc: live-patching, jniethe5, naveen.n.rao
On Tue, 2021-12-07 at 09:44 -0500, Joe Lawrence wrote:
> On 11/23/21 3:15 AM, Russell Currey wrote:
>
> [[ cc += livepatching list ]]
>
> Hi Russell,
>
> Thanks for writing a minimal fix for stable / backporting. As I
> mentioned on the github issue [1], this avoided the crashes I
> reported
> here and over on kpatch github [2]. I wasn't sure if this is the
> final
> version for stable, but feel free to add my:
>
> Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Thanks Joe, as per the discussions on GitHub I think we're fine to use
this patch for a fix for stable (unless there's new issues found or
additional community feedback etc).
>
> [1] https://github.com/linuxppc/issues/issues/375
> [2] https://github.com/dynup/kpatch/issues/1228
>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
2021-12-08 1:51 ` Russell Currey
@ 2021-12-09 7:00 ` Michael Ellerman
-1 siblings, 0 replies; 10+ messages in thread
From: Michael Ellerman @ 2021-12-09 7:00 UTC (permalink / raw)
To: Russell Currey, Joe Lawrence, linuxppc-dev
Cc: jniethe5, naveen.n.rao, christophe.leroy, live-patching
Russell Currey <ruscur@russell.cc> writes:
> On Tue, 2021-12-07 at 09:44 -0500, Joe Lawrence wrote:
>> On 11/23/21 3:15 AM, Russell Currey wrote:
>>
>> [[ cc += livepatching list ]]
>>
>> Hi Russell,
>>
>> Thanks for writing a minimal fix for stable / backporting. As I
>> mentioned on the github issue [1], this avoided the crashes I
>> reported
>> here and over on kpatch github [2]. I wasn't sure if this is the
>> final
>> version for stable, but feel free to add my:
>>
>> Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
>
> Thanks Joe, as per the discussions on GitHub I think we're fine to use
> this patch for a fix for stable (unless there's new issues found or
> additional community feedback etc).
Hmm, I read the GitHub discussion as being that you were going to do
another version, which is why I haven't picked this up. But I guess you
and Christophe were talking about the non-minimal fix.
I know we want this to be minimal, but I think it should be checking
that patch_instruction() isn't failing.
Incremental diff to do that is below. It boots OK, are you able to throw
a livepatch test at it?
cheers
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index c25ef36c3ef4..5d77d3f5fbb5 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -429,8 +429,9 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
return create_ftrace_stub(entry, addr, me);
for (i = 0; i < sizeof(ppc64_stub_insns) / sizeof(u32); i++) {
- patch_instruction(&entry->jump[i],
- ppc_inst(ppc64_stub_insns[i]));
+ if (patch_instruction(&entry->jump[i],
+ ppc_inst(ppc64_stub_insns[i])))
+ return 0;
}
/* Stub uses address relative to r2. */
@@ -442,19 +443,24 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
}
pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
- patch_instruction(&entry->jump[0],
- ppc_inst(entry->jump[0] | PPC_HA(reladdr)));
- patch_instruction(&entry->jump[1],
- ppc_inst(entry->jump[1] | PPC_LO(reladdr)));
+ if (patch_instruction(&entry->jump[0],
+ ppc_inst(entry->jump[0] | PPC_HA(reladdr))))
+ return 0;
+
+ if (patch_instruction(&entry->jump[1],
+ ppc_inst(entry->jump[1] | PPC_LO(reladdr))))
+ return 0;
// func_desc_t is 8 bytes if ABIv2, else 16 bytes
desc = func_desc(addr);
for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
- patch_instruction(((u32 *)&entry->funcdata) + i,
- ppc_inst(((u32 *)(&desc))[i]));
+ if (patch_instruction(((u32 *)&entry->funcdata) + i,
+ ppc_inst(((u32 *)(&desc))[i])))
+ return 0;
}
- patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC));
+ if (patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC)))
+ return 0;
return 1;
}
@@ -509,8 +515,11 @@ static int restore_r2(const char *name, u32 *instruction, struct module *me)
me->name, *instruction, instruction);
return 0;
}
+
/* ld r2,R2_STACK_OFFSET(r1) */
- patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
+ if (patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC)))
+ return 0;
+
return 1;
}
@@ -652,7 +661,10 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
/* Only replace bits 2 through 26 */
value = (*(uint32_t *)location & ~0x03fffffc)
| (value & 0x03fffffc);
- patch_instruction((u32 *)location, ppc_inst(value));
+
+ if (patch_instruction((u32 *)location, ppc_inst(value)))
+ return -EFAULT;
+
break;
case R_PPC64_REL64:
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
@ 2021-12-09 7:00 ` Michael Ellerman
0 siblings, 0 replies; 10+ messages in thread
From: Michael Ellerman @ 2021-12-09 7:00 UTC (permalink / raw)
To: Russell Currey, Joe Lawrence, linuxppc-dev
Cc: jniethe5, naveen.n.rao, live-patching
Russell Currey <ruscur@russell.cc> writes:
> On Tue, 2021-12-07 at 09:44 -0500, Joe Lawrence wrote:
>> On 11/23/21 3:15 AM, Russell Currey wrote:
>>
>> [[ cc += livepatching list ]]
>>
>> Hi Russell,
>>
>> Thanks for writing a minimal fix for stable / backporting. As I
>> mentioned on the github issue [1], this avoided the crashes I
>> reported
>> here and over on kpatch github [2]. I wasn't sure if this is the
>> final
>> version for stable, but feel free to add my:
>>
>> Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
>
> Thanks Joe, as per the discussions on GitHub I think we're fine to use
> this patch for a fix for stable (unless there's new issues found or
> additional community feedback etc).
Hmm, I read the GitHub discussion as being that you were going to do
another version, which is why I haven't picked this up. But I guess you
and Christophe were talking about the non-minimal fix.
I know we want this to be minimal, but I think it should be checking
that patch_instruction() isn't failing.
Incremental diff to do that is below. It boots OK, are you able to throw
a livepatch test at it?
cheers
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index c25ef36c3ef4..5d77d3f5fbb5 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -429,8 +429,9 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
return create_ftrace_stub(entry, addr, me);
for (i = 0; i < sizeof(ppc64_stub_insns) / sizeof(u32); i++) {
- patch_instruction(&entry->jump[i],
- ppc_inst(ppc64_stub_insns[i]));
+ if (patch_instruction(&entry->jump[i],
+ ppc_inst(ppc64_stub_insns[i])))
+ return 0;
}
/* Stub uses address relative to r2. */
@@ -442,19 +443,24 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
}
pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
- patch_instruction(&entry->jump[0],
- ppc_inst(entry->jump[0] | PPC_HA(reladdr)));
- patch_instruction(&entry->jump[1],
- ppc_inst(entry->jump[1] | PPC_LO(reladdr)));
+ if (patch_instruction(&entry->jump[0],
+ ppc_inst(entry->jump[0] | PPC_HA(reladdr))))
+ return 0;
+
+ if (patch_instruction(&entry->jump[1],
+ ppc_inst(entry->jump[1] | PPC_LO(reladdr))))
+ return 0;
// func_desc_t is 8 bytes if ABIv2, else 16 bytes
desc = func_desc(addr);
for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
- patch_instruction(((u32 *)&entry->funcdata) + i,
- ppc_inst(((u32 *)(&desc))[i]));
+ if (patch_instruction(((u32 *)&entry->funcdata) + i,
+ ppc_inst(((u32 *)(&desc))[i])))
+ return 0;
}
- patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC));
+ if (patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC)))
+ return 0;
return 1;
}
@@ -509,8 +515,11 @@ static int restore_r2(const char *name, u32 *instruction, struct module *me)
me->name, *instruction, instruction);
return 0;
}
+
/* ld r2,R2_STACK_OFFSET(r1) */
- patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
+ if (patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC)))
+ return 0;
+
return 1;
}
@@ -652,7 +661,10 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
/* Only replace bits 2 through 26 */
value = (*(uint32_t *)location & ~0x03fffffc)
| (value & 0x03fffffc);
- patch_instruction((u32 *)location, ppc_inst(value));
+
+ if (patch_instruction((u32 *)location, ppc_inst(value)))
+ return -EFAULT;
+
break;
case R_PPC64_REL64:
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
2021-12-09 7:00 ` Michael Ellerman
@ 2021-12-10 3:08 ` Joe Lawrence
-1 siblings, 0 replies; 10+ messages in thread
From: Joe Lawrence @ 2021-12-10 3:08 UTC (permalink / raw)
To: Michael Ellerman, Russell Currey, linuxppc-dev
Cc: jniethe5, naveen.n.rao, christophe.leroy, live-patching
On 12/9/21 2:00 AM, Michael Ellerman wrote:
> Russell Currey <ruscur@russell.cc> writes:
>> On Tue, 2021-12-07 at 09:44 -0500, Joe Lawrence wrote:
>>> On 11/23/21 3:15 AM, Russell Currey wrote:
>>>
>>> [[ cc += livepatching list ]]
>>>
>>> Hi Russell,
>>>
>>> Thanks for writing a minimal fix for stable / backporting. As I
>>> mentioned on the github issue [1], this avoided the crashes I
>>> reported
>>> here and over on kpatch github [2]. I wasn't sure if this is the
>>> final
>>> version for stable, but feel free to add my:
>>>
>>> Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
>>
>> Thanks Joe, as per the discussions on GitHub I think we're fine to use
>> this patch for a fix for stable (unless there's new issues found or
>> additional community feedback etc).
>
> Hmm, I read the GitHub discussion as being that you were going to do
> another version, which is why I haven't picked this up. But I guess you
> and Christophe were talking about the non-minimal fix.
>
> I know we want this to be minimal, but I think it should be checking
> that patch_instruction() isn't failing.
>
> Incremental diff to do that is below. It boots OK, are you able to throw
> a livepatch test at it?
>
No problem. The incremental patch update tests successful.
Thanks,
--
Joe
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
@ 2021-12-10 3:08 ` Joe Lawrence
0 siblings, 0 replies; 10+ messages in thread
From: Joe Lawrence @ 2021-12-10 3:08 UTC (permalink / raw)
To: Michael Ellerman, Russell Currey, linuxppc-dev
Cc: jniethe5, naveen.n.rao, live-patching
On 12/9/21 2:00 AM, Michael Ellerman wrote:
> Russell Currey <ruscur@russell.cc> writes:
>> On Tue, 2021-12-07 at 09:44 -0500, Joe Lawrence wrote:
>>> On 11/23/21 3:15 AM, Russell Currey wrote:
>>>
>>> [[ cc += livepatching list ]]
>>>
>>> Hi Russell,
>>>
>>> Thanks for writing a minimal fix for stable / backporting. As I
>>> mentioned on the github issue [1], this avoided the crashes I
>>> reported
>>> here and over on kpatch github [2]. I wasn't sure if this is the
>>> final
>>> version for stable, but feel free to add my:
>>>
>>> Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
>>
>> Thanks Joe, as per the discussions on GitHub I think we're fine to use
>> this patch for a fix for stable (unless there's new issues found or
>> additional community feedback etc).
>
> Hmm, I read the GitHub discussion as being that you were going to do
> another version, which is why I haven't picked this up. But I guess you
> and Christophe were talking about the non-minimal fix.
>
> I know we want this to be minimal, but I think it should be checking
> that patch_instruction() isn't failing.
>
> Incremental diff to do that is below. It boots OK, are you able to throw
> a livepatch test at it?
>
No problem. The incremental patch update tests successful.
Thanks,
--
Joe
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] powerpc/module_64: Fix livepatching for RO modules
2021-11-23 8:15 [PATCH] powerpc/module_64: Fix livepatching for RO modules Russell Currey
2021-12-07 14:44 ` Joe Lawrence
@ 2021-12-15 0:51 ` Michael Ellerman
1 sibling, 0 replies; 10+ messages in thread
From: Michael Ellerman @ 2021-12-15 0:51 UTC (permalink / raw)
To: linuxppc-dev, Russell Currey; +Cc: jniethe5, naveen.n.rao, Joe Lawrence
On Tue, 23 Nov 2021 18:15:20 +1000, Russell Currey wrote:
> Livepatching a loaded module involves applying relocations through
> apply_relocate_add(), which attempts to write to read-only memory when
> CONFIG_STRICT_MODULE_RWX=y. Work around this by performing these
> writes through the text poke area by using patch_instruction().
>
> R_PPC_REL24 is the only relocation type generated by the kpatch-build
> userspace tool or klp-convert kernel tree that I observed applying a
> relocation to a post-init module.
>
> [...]
Applied to powerpc/fixes.
[1/1] powerpc/module_64: Fix livepatching for RO modules
https://git.kernel.org/powerpc/c/8734b41b3efe0fc6082c1937b0e88556c396dc96
cheers
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2021-12-15 0:51 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-23 8:15 [PATCH] powerpc/module_64: Fix livepatching for RO modules Russell Currey
2021-12-07 14:44 ` Joe Lawrence
2021-12-07 14:44 ` Joe Lawrence
2021-12-08 1:51 ` Russell Currey
2021-12-08 1:51 ` Russell Currey
2021-12-09 7:00 ` Michael Ellerman
2021-12-09 7:00 ` Michael Ellerman
2021-12-10 3:08 ` Joe Lawrence
2021-12-10 3:08 ` Joe Lawrence
2021-12-15 0:51 ` Michael Ellerman
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