Instead of stacking alternative and paravirt patching, use the new
ALT_FLAG_CALL flag to switch those mixed calls to pure alternative
handling.
This eliminates the need to be careful regarding the sequence of
alternative and paravirt patching.
For call depth tracking callthunks_setup() needs to be adapted to patch
calls at alternative patching sites instead of paravirt calls.
Signed-off-by: Juergen Gross <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
---
arch/x86/include/asm/alternative.h | 5 +++--
arch/x86/include/asm/paravirt.h | 9 ++++++---
arch/x86/include/asm/paravirt_types.h | 26 +++++++++-----------------
arch/x86/kernel/callthunks.c | 17 ++++++++---------
arch/x86/kernel/module.c | 20 +++++---------------
5 files changed, 31 insertions(+), 46 deletions(-)
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 2a74a94bd569..07b17bc615a0 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -89,6 +89,8 @@ struct alt_instr {
u8 replacementlen; /* length of new instruction */
} __packed;
+extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
+
/*
* Debug flag that can be tested to see whether alternative
* instructions were patched in already:
@@ -104,11 +106,10 @@ extern void apply_fineibt(s32 *start_retpoline, s32 *end_retpoine,
s32 *start_cfi, s32 *end_cfi);
struct module;
-struct paravirt_patch_site;
struct callthunk_sites {
s32 *call_start, *call_end;
- struct paravirt_patch_site *pv_start, *pv_end;
+ struct alt_instr *alt_start, *alt_end;
};
#ifdef CONFIG_CALL_THUNKS
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 3749311d51c3..9c6c5cfa9fe2 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -740,20 +740,23 @@ void native_pv_lock_init(void) __init;
#ifdef CONFIG_X86_64
#ifdef CONFIG_PARAVIRT_XXL
+#ifdef CONFIG_DEBUG_ENTRY
#define PARA_PATCH(off) ((off) / 8)
#define PARA_SITE(ptype, ops) _PVSITE(ptype, ops, .quad, 8)
#define PARA_INDIRECT(addr) *addr(%rip)
-#ifdef CONFIG_DEBUG_ENTRY
.macro PARA_IRQ_save_fl
PARA_SITE(PARA_PATCH(PV_IRQ_save_fl),
ANNOTATE_RETPOLINE_SAFE;
call PARA_INDIRECT(pv_ops+PV_IRQ_save_fl);)
+ ANNOTATE_RETPOLINE_SAFE;
+ call PARA_INDIRECT(pv_ops+PV_IRQ_save_fl);
.endm
-#define SAVE_FLAGS ALTERNATIVE "PARA_IRQ_save_fl;", "pushf; pop %rax;", \
- ALT_NOT_XEN
+#define SAVE_FLAGS ALTERNATIVE_2 "PARA_IRQ_save_fl;", \
+ ALT_CALL_INSTR, ALT_CALL_ALWAYS, \
+ "pushf; pop %rax;", ALT_NOT_XEN
#endif
#endif /* CONFIG_PARAVIRT_XXL */
#endif /* CONFIG_X86_64 */
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 291d794f2344..9b0526967d69 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -278,15 +278,11 @@ extern struct paravirt_patch_template pv_ops;
#define NATIVE_LABEL(a,x,b) "\n\t.globl " a #x "_" #b "\n" a #x "_" #b ":\n\t"
unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr, unsigned int len);
+#define paravirt_ptr(op) [paravirt_opptr] "m" (pv_ops.op)
int paravirt_disable_iospace(void);
-/*
- * This generates an indirect call based on the operation type number.
- * The type number, computed in PARAVIRT_PATCH, is derived from the
- * offset into the paravirt_patch_template structure, and can therefore be
- * freely converted back into a structure offset.
- */
+/* This generates an indirect call based on the operation type number. */
#define PARAVIRT_CALL \
ANNOTATE_RETPOLINE_SAFE \
"call *%[paravirt_opptr];"
@@ -319,12 +315,6 @@ int paravirt_disable_iospace(void);
* However, x86_64 also has to clobber all caller saved registers, which
* unfortunately, are quite a bit (r8 - r11)
*
- * The call instruction itself is marked by placing its start address
- * and size into the .parainstructions section, so that
- * apply_paravirt() in arch/i386/kernel/alternative.c can do the
- * appropriate patching under the control of the backend pv_init_ops
- * implementation.
- *
* Unfortunately there's no way to get gcc to generate the args setup
* for the call, and then allow the call itself to be generated by an
* inline asm. Because of this, we must do the complete arg setup and
@@ -428,9 +418,10 @@ int paravirt_disable_iospace(void);
({ \
PVOP_CALL_ARGS; \
PVOP_TEST_NULL(op); \
- asm volatile(paravirt_alt(PARAVIRT_CALL) \
+ asm volatile(ALTERNATIVE(PARAVIRT_CALL, ALT_CALL_INSTR, \
+ ALT_CALL_ALWAYS) \
: call_clbr, ASM_CALL_CONSTRAINT \
- : paravirt_type(op), \
+ : paravirt_ptr(op), \
##__VA_ARGS__ \
: "memory", "cc" extra_clbr); \
ret; \
@@ -441,10 +432,11 @@ int paravirt_disable_iospace(void);
({ \
PVOP_CALL_ARGS; \
PVOP_TEST_NULL(op); \
- asm volatile(ALTERNATIVE(paravirt_alt(PARAVIRT_CALL), \
- alt, cond) \
+ asm volatile(ALTERNATIVE_2(PARAVIRT_CALL, \
+ ALT_CALL_INSTR, ALT_CALL_ALWAYS, \
+ alt, cond) \
: call_clbr, ASM_CALL_CONSTRAINT \
- : paravirt_type(op), \
+ : paravirt_ptr(op), \
##__VA_ARGS__ \
: "memory", "cc" extra_clbr); \
ret; \
diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
index faa9f2299848..200ea8087ddb 100644
--- a/arch/x86/kernel/callthunks.c
+++ b/arch/x86/kernel/callthunks.c
@@ -238,14 +238,13 @@ patch_call_sites(s32 *start, s32 *end, const struct core_text *ct)
}
static __init_or_module void
-patch_paravirt_call_sites(struct paravirt_patch_site *start,
- struct paravirt_patch_site *end,
- const struct core_text *ct)
+patch_alt_call_sites(struct alt_instr *start, struct alt_instr *end,
+ const struct core_text *ct)
{
- struct paravirt_patch_site *p;
+ struct alt_instr *a;
- for (p = start; p < end; p++)
- patch_call(p->instr, ct);
+ for (a = start; a < end; a++)
+ patch_call((u8 *)&a->instr_offset + a->instr_offset, ct);
}
static __init_or_module void
@@ -253,7 +252,7 @@ callthunks_setup(struct callthunk_sites *cs, const struct core_text *ct)
{
prdbg("Patching call sites %s\n", ct->name);
patch_call_sites(cs->call_start, cs->call_end, ct);
- patch_paravirt_call_sites(cs->pv_start, cs->pv_end, ct);
+ patch_alt_call_sites(cs->alt_start, cs->alt_end, ct);
prdbg("Patching call sites done%s\n", ct->name);
}
@@ -262,8 +261,8 @@ void __init callthunks_patch_builtin_calls(void)
struct callthunk_sites cs = {
.call_start = __call_sites,
.call_end = __call_sites_end,
- .pv_start = __parainstructions,
- .pv_end = __parainstructions_end
+ .alt_start = __alt_instructions,
+ .alt_end = __alt_instructions_end
};
if (!cpu_feature_enabled(X86_FEATURE_CALL_DEPTH))
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 5f71a0cf4399..e18914c0e38a 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -276,7 +276,7 @@ int module_finalize(const Elf_Ehdr *hdr,
struct module *me)
{
const Elf_Shdr *s, *alt = NULL, *locks = NULL,
- *para = NULL, *orc = NULL, *orc_ip = NULL,
+ *orc = NULL, *orc_ip = NULL,
*retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,
*calls = NULL, *cfi = NULL;
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
@@ -286,8 +286,6 @@ int module_finalize(const Elf_Ehdr *hdr,
alt = s;
if (!strcmp(".smp_locks", secstrings + s->sh_name))
locks = s;
- if (!strcmp(".parainstructions", secstrings + s->sh_name))
- para = s;
if (!strcmp(".orc_unwind", secstrings + s->sh_name))
orc = s;
if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
@@ -304,14 +302,6 @@ int module_finalize(const Elf_Ehdr *hdr,
ibt_endbr = s;
}
- /*
- * See alternative_instructions() for the ordering rules between the
- * various patching types.
- */
- if (para) {
- void *pseg = (void *)para->sh_addr;
- apply_paravirt(pseg, pseg + para->sh_size);
- }
if (retpolines || cfi) {
void *rseg = NULL, *cseg = NULL;
unsigned int rsize = 0, csize = 0;
@@ -341,7 +331,7 @@ int module_finalize(const Elf_Ehdr *hdr,
void *aseg = (void *)alt->sh_addr;
apply_alternatives(aseg, aseg + alt->sh_size);
}
- if (calls || para) {
+ if (calls || alt) {
struct callthunk_sites cs = {};
if (calls) {
@@ -349,9 +339,9 @@ int module_finalize(const Elf_Ehdr *hdr,
cs.call_end = (void *)calls->sh_addr + calls->sh_size;
}
- if (para) {
- cs.pv_start = (void *)para->sh_addr;
- cs.pv_end = (void *)para->sh_addr + para->sh_size;
+ if (alt) {
+ cs.alt_start = (void *)alt->sh_addr;
+ cs.alt_end = (void *)alt->sh_addr + alt->sh_size;
}
callthunks_patch_module_calls(&cs, me);
--
2.35.3
On Mon, Oct 30, 2023 at 03:25:07PM +0100, Juergen Gross wrote:
> Instead of stacking alternative and paravirt patching, use the new
> ALT_FLAG_CALL flag to switch those mixed calls to pure alternative
> handling.
>
> This eliminates the need to be careful regarding the sequence of
> alternative and paravirt patching.
>
> For call depth tracking callthunks_setup() needs to be adapted to patch
> calls at alternative patching sites instead of paravirt calls.
Why is this important so that it is called out explicitly in the commit
message? Is callthunks_setup() special somehow?
>
> Signed-off-by: Juergen Gross <[email protected]>
> Acked-by: Peter Zijlstra (Intel) <[email protected]>
> ---
> arch/x86/include/asm/alternative.h | 5 +++--
> arch/x86/include/asm/paravirt.h | 9 ++++++---
> arch/x86/include/asm/paravirt_types.h | 26 +++++++++-----------------
> arch/x86/kernel/callthunks.c | 17 ++++++++---------
> arch/x86/kernel/module.c | 20 +++++---------------
> 5 files changed, 31 insertions(+), 46 deletions(-)
>
> diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
> index 2a74a94bd569..07b17bc615a0 100644
> --- a/arch/x86/include/asm/alternative.h
> +++ b/arch/x86/include/asm/alternative.h
> @@ -89,6 +89,8 @@ struct alt_instr {
> u8 replacementlen; /* length of new instruction */
> } __packed;
>
> +extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
> +
arch/x86/include/asm/alternative.h:92:extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
arch/x86/kernel/alternative.c:163:extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
Zap the declaration from the .c file pls.
> /*
> * Debug flag that can be tested to see whether alternative
> * instructions were patched in already:
> @@ -104,11 +106,10 @@ extern void apply_fineibt(s32 *start_retpoline, s32 *end_retpoine,
> s32 *start_cfi, s32 *end_cfi);
>
> struct module;
> -struct paravirt_patch_site;
>
> struct callthunk_sites {
> s32 *call_start, *call_end;
> - struct paravirt_patch_site *pv_start, *pv_end;
> + struct alt_instr *alt_start, *alt_end;
> };
>
> #ifdef CONFIG_CALL_THUNKS
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index 3749311d51c3..9c6c5cfa9fe2 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -740,20 +740,23 @@ void native_pv_lock_init(void) __init;
>
> #ifdef CONFIG_X86_64
> #ifdef CONFIG_PARAVIRT_XXL
> +#ifdef CONFIG_DEBUG_ENTRY
>
> #define PARA_PATCH(off) ((off) / 8)
> #define PARA_SITE(ptype, ops) _PVSITE(ptype, ops, .quad, 8)
> #define PARA_INDIRECT(addr) *addr(%rip)
>
> -#ifdef CONFIG_DEBUG_ENTRY
> .macro PARA_IRQ_save_fl
> PARA_SITE(PARA_PATCH(PV_IRQ_save_fl),
> ANNOTATE_RETPOLINE_SAFE;
> call PARA_INDIRECT(pv_ops+PV_IRQ_save_fl);)
> + ANNOTATE_RETPOLINE_SAFE;
> + call PARA_INDIRECT(pv_ops+PV_IRQ_save_fl);
> .endm
>
> -#define SAVE_FLAGS ALTERNATIVE "PARA_IRQ_save_fl;", "pushf; pop %rax;", \
> - ALT_NOT_XEN
> +#define SAVE_FLAGS ALTERNATIVE_2 "PARA_IRQ_save_fl;", \
> + ALT_CALL_INSTR, ALT_CALL_ALWAYS, \
> + "pushf; pop %rax;", ALT_NOT_XEN
How is that supposed to work?
At build time for a PARAVIRT_XXL build it'll have that PARA_IRQ_save_fl
macro in there which issues a .parainstructions section and an indirect
call to
call *pv_ops+240(%rip);
then it'll always patch in "call BUG_func" due to X86_FEATURE_ALWAYS.
I guess this is your way of saying "this should always be patched, one
way or the other, depending on X86_FEATURE_XENPV, and this is a way to
catch unpatched locations...
Then on a pv build which doesn't set X86_FEATURE_XENPV during boot,
it'll replace the "call BUG_func" thing with the pushf;pop.
And if it does set X86_FEATURE_XENPV, it'll patch in the direct call to
.... /me greps tree ... pv_native_save_fl I guess.
If anything, how those ALT_CALL_ALWAYS things are supposed to work,
should be documented there, over the macro definition and what the
intent is.
Because otherwise we'll have to swap in the whole machinery back into
our L1s each time we need to touch it.
And btw, this whole patching stuff becomes insanely non-trivial slowly.
:-\
> diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
> index faa9f2299848..200ea8087ddb 100644
> --- a/arch/x86/kernel/callthunks.c
> +++ b/arch/x86/kernel/callthunks.c
> @@ -238,14 +238,13 @@ patch_call_sites(s32 *start, s32 *end, const struct core_text *ct)
> }
>
> static __init_or_module void
> -patch_paravirt_call_sites(struct paravirt_patch_site *start,
> - struct paravirt_patch_site *end,
> - const struct core_text *ct)
> +patch_alt_call_sites(struct alt_instr *start, struct alt_instr *end,
> + const struct core_text *ct)
> {
> - struct paravirt_patch_site *p;
> + struct alt_instr *a;
>
> - for (p = start; p < end; p++)
> - patch_call(p->instr, ct);
> + for (a = start; a < end; a++)
> + patch_call((u8 *)&a->instr_offset + a->instr_offset, ct);
tip:x86/paravirt has:
5c22c4726e4a ("x86/paravirt: Use relative reference for the original instruction offset")
Perhaps redo yours ontop of tip/master:
diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
index 57e5c2e75c2a..76414aba116d 100644
--- a/arch/x86/kernel/callthunks.c
+++ b/arch/x86/kernel/callthunks.c
@@ -233,14 +233,18 @@ patch_call_sites(s32 *start, s32 *end, const struct core_text *ct)
}
static __init_or_module void
-patch_paravirt_call_sites(struct paravirt_patch_site *start,
- struct paravirt_patch_site *end,
- const struct core_text *ct)
+patch_alt_call_sites(struct alt_instr *start, struct alt_instr *end,
+ const struct core_text *ct)
{
- struct paravirt_patch_site *p;
+ struct alt_instr *a;
+<<<<<<<
for (p = start; p < end; p++)
patch_call((void *)&p->instr_offset + p->instr_offset, ct);
+=======
+ for (a = start; a < end; a++)
+ patch_call((u8 *)&a->instr_offset + a->instr_offset, ct);
+>>>>>>>
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On 21.11.23 19:45, Borislav Petkov wrote:
> On Mon, Oct 30, 2023 at 03:25:07PM +0100, Juergen Gross wrote:
>> Instead of stacking alternative and paravirt patching, use the new
>> ALT_FLAG_CALL flag to switch those mixed calls to pure alternative
>> handling.
>>
>> This eliminates the need to be careful regarding the sequence of
>> alternative and paravirt patching.
>>
>> For call depth tracking callthunks_setup() needs to be adapted to patch
>> calls at alternative patching sites instead of paravirt calls.
>
> Why is this important so that it is called out explicitly in the commit
> message? Is callthunks_setup() special somehow?
IMHO it is a non-obvious change, so I spelled it out explicitly. I can drop
that paragraph if you want.
>
>>
>> Signed-off-by: Juergen Gross <[email protected]>
>> Acked-by: Peter Zijlstra (Intel) <[email protected]>
>> ---
>> arch/x86/include/asm/alternative.h | 5 +++--
>> arch/x86/include/asm/paravirt.h | 9 ++++++---
>> arch/x86/include/asm/paravirt_types.h | 26 +++++++++-----------------
>> arch/x86/kernel/callthunks.c | 17 ++++++++---------
>> arch/x86/kernel/module.c | 20 +++++---------------
>> 5 files changed, 31 insertions(+), 46 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
>> index 2a74a94bd569..07b17bc615a0 100644
>> --- a/arch/x86/include/asm/alternative.h
>> +++ b/arch/x86/include/asm/alternative.h
>> @@ -89,6 +89,8 @@ struct alt_instr {
>> u8 replacementlen; /* length of new instruction */
>> } __packed;
>>
>> +extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
>> +
>
> arch/x86/include/asm/alternative.h:92:extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
> arch/x86/kernel/alternative.c:163:extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
>
> Zap the declaration from the .c file pls.
Okay.
>
>> /*
>> * Debug flag that can be tested to see whether alternative
>> * instructions were patched in already:
>> @@ -104,11 +106,10 @@ extern void apply_fineibt(s32 *start_retpoline, s32 *end_retpoine,
>> s32 *start_cfi, s32 *end_cfi);
>>
>> struct module;
>> -struct paravirt_patch_site;
>>
>> struct callthunk_sites {
>> s32 *call_start, *call_end;
>> - struct paravirt_patch_site *pv_start, *pv_end;
>> + struct alt_instr *alt_start, *alt_end;
>> };
>>
>> #ifdef CONFIG_CALL_THUNKS
>> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
>> index 3749311d51c3..9c6c5cfa9fe2 100644
>> --- a/arch/x86/include/asm/paravirt.h
>> +++ b/arch/x86/include/asm/paravirt.h
>> @@ -740,20 +740,23 @@ void native_pv_lock_init(void) __init;
>>
>> #ifdef CONFIG_X86_64
>> #ifdef CONFIG_PARAVIRT_XXL
>> +#ifdef CONFIG_DEBUG_ENTRY
>>
>> #define PARA_PATCH(off) ((off) / 8)
>> #define PARA_SITE(ptype, ops) _PVSITE(ptype, ops, .quad, 8)
>> #define PARA_INDIRECT(addr) *addr(%rip)
>>
>> -#ifdef CONFIG_DEBUG_ENTRY
>> .macro PARA_IRQ_save_fl
>> PARA_SITE(PARA_PATCH(PV_IRQ_save_fl),
>> ANNOTATE_RETPOLINE_SAFE;
>> call PARA_INDIRECT(pv_ops+PV_IRQ_save_fl);)
>> + ANNOTATE_RETPOLINE_SAFE;
>> + call PARA_INDIRECT(pv_ops+PV_IRQ_save_fl);
>> .endm
>>
>> -#define SAVE_FLAGS ALTERNATIVE "PARA_IRQ_save_fl;", "pushf; pop %rax;", \
>> - ALT_NOT_XEN
>> +#define SAVE_FLAGS ALTERNATIVE_2 "PARA_IRQ_save_fl;", \
>> + ALT_CALL_INSTR, ALT_CALL_ALWAYS, \
>> + "pushf; pop %rax;", ALT_NOT_XEN
>
> How is that supposed to work?
>
> At build time for a PARAVIRT_XXL build it'll have that PARA_IRQ_save_fl
> macro in there which issues a .parainstructions section and an indirect
> call to
>
> call *pv_ops+240(%rip);
>
> then it'll always patch in "call BUG_func" due to X86_FEATURE_ALWAYS.
>
> I guess this is your way of saying "this should always be patched, one
> way or the other, depending on X86_FEATURE_XENPV, and this is a way to
> catch unpatched locations...
>
> Then on a pv build which doesn't set X86_FEATURE_XENPV during boot,
> it'll replace the "call BUG_func" thing with the pushf;pop.
>
> And if it does set X86_FEATURE_XENPV, it'll patch in the direct call to
> .... /me greps tree ... pv_native_save_fl I guess.
>
> If anything, how those ALT_CALL_ALWAYS things are supposed to work,
> should be documented there, over the macro definition and what the
> intent is.
I can do that, but OTOH the existing comments are quite clear:
* If CPU has feature2, newinstr2 is used.
* Otherwise, if CPU has feature1, newinstr1 is used.
* Otherwise, oldinstr is used.
>
> Because otherwise we'll have to swap in the whole machinery back into
> our L1s each time we need to touch it.
>
> And btw, this whole patching stuff becomes insanely non-trivial slowly.
Not worse than today. It just replaces the paravirt patching with an
alternative patching.
>
> :-\
>
>> diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
>> index faa9f2299848..200ea8087ddb 100644
>> --- a/arch/x86/kernel/callthunks.c
>> +++ b/arch/x86/kernel/callthunks.c
>> @@ -238,14 +238,13 @@ patch_call_sites(s32 *start, s32 *end, const struct core_text *ct)
>> }
>>
>> static __init_or_module void
>> -patch_paravirt_call_sites(struct paravirt_patch_site *start,
>> - struct paravirt_patch_site *end,
>> - const struct core_text *ct)
>> +patch_alt_call_sites(struct alt_instr *start, struct alt_instr *end,
>> + const struct core_text *ct)
>> {
>> - struct paravirt_patch_site *p;
>> + struct alt_instr *a;
>>
>> - for (p = start; p < end; p++)
>> - patch_call(p->instr, ct);
>> + for (a = start; a < end; a++)
>> + patch_call((u8 *)&a->instr_offset + a->instr_offset, ct);
>
> tip:x86/paravirt has:
>
> 5c22c4726e4a ("x86/paravirt: Use relative reference for the original instruction offset")
>
> Perhaps redo yours ontop of tip/master:
Yes, of course.
Juergen