For x86 PIE binary, only RIP-relative addressing is allowed, however,
there are still a little absolute references of R_X86_64_64 relocation
type for data section and a little absolute references of R_X86_64_32S
relocation type in pvh_start_xen() function.
Suggested-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Cc: Thomas Garnier <thgarnie@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
---
arch/x86/Kconfig | 1 +
scripts/Makefile.lib | 1 +
tools/objtool/builtin-check.c | 4 +-
tools/objtool/check.c | 82 +++++++++++++++++++++++++
tools/objtool/include/objtool/builtin.h | 1 +
5 files changed, 88 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 715f0734d065..b753a54e5ea7 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2224,6 +2224,7 @@ config RELOCATABLE
config X86_PIE
def_bool n
depends on X86_64
+ select OBJTOOL if HAVE_OBJTOOL
config RANDOMIZE_BASE
bool "Randomize the address of the kernel image (KASLR)"
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 100a386fcd71..e3c804fbc421 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -270,6 +270,7 @@ objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE) += --static-call
objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION) += --uaccess
objtool-args-$(CONFIG_GCOV_KERNEL) += --no-unreachable
objtool-args-$(CONFIG_PREFIX_SYMBOLS) += --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
+objtool-args-$(CONFIG_X86_PIE) += --pie
objtool-args = $(objtool-args-y) \
$(if $(delay-objtool), --link) \
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 7c175198d09f..1cf1d00464e0 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -81,6 +81,7 @@ static const struct option check_options[] = {
OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"),
OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
+ OPT_BOOLEAN(0, "pie", &opts.pie, "validate addressing rules for PIE"),
OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
OPT_GROUP("Options:"),
@@ -137,7 +138,8 @@ static bool opts_valid(void)
opts.sls ||
opts.stackval ||
opts.static_call ||
- opts.uaccess) {
+ opts.uaccess ||
+ opts.pie) {
if (opts.dump_orc) {
ERROR("--dump can't be combined with other options");
return false;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 5b600bbf2389..d67b80251eec 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -131,6 +131,27 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
for (insn = next_insn_same_sec(file, insn); insn; \
insn = next_insn_same_sec(file, insn))
+static struct instruction *find_insn_containing(struct objtool_file *file,
+ struct section *sec,
+ unsigned long offset)
+{
+ struct instruction *insn;
+
+ insn = find_insn(file, sec, 0);
+ if (!insn)
+ return NULL;
+
+ sec_for_each_insn_from(file, insn) {
+ if (insn->offset > offset)
+ return NULL;
+ if (insn->offset <= offset && (insn->offset + insn->len) > offset)
+ return insn;
+ }
+
+ return NULL;
+}
+
+
static inline struct symbol *insn_call_dest(struct instruction *insn)
{
if (insn->type == INSN_JUMP_DYNAMIC ||
@@ -4529,6 +4550,61 @@ static int validate_reachable_instructions(struct objtool_file *file)
return 0;
}
+static int is_in_pvh_code(struct instruction *insn)
+{
+ struct symbol *sym = insn->sym;
+
+ return sym && !strcmp(sym->name, "pvh_start_xen");
+}
+
+static int validate_pie(struct objtool_file *file)
+{
+ struct section *sec;
+ struct reloc *reloc;
+ struct instruction *insn;
+ int warnings = 0;
+
+ for_each_sec(file, sec) {
+ if (!sec->reloc)
+ continue;
+ if (!(sec->sh.sh_flags & SHF_ALLOC))
+ continue;
+
+ list_for_each_entry(reloc, &sec->reloc->reloc_list, list) {
+ switch (reloc->type) {
+ case R_X86_64_NONE:
+ case R_X86_64_PC32:
+ case R_X86_64_PLT32:
+ case R_X86_64_64:
+ case R_X86_64_PC64:
+ case R_X86_64_GOTPCREL:
+ break;
+ case R_X86_64_32:
+ case R_X86_64_32S:
+ insn = find_insn_containing(file, sec, reloc->offset);
+ if (!insn) {
+ WARN("can't find relocate insn near %s+0x%lx",
+ sec->name, reloc->offset);
+ } else {
+ if (is_in_pvh_code(insn))
+ break;
+ WARN("insn at %s+0x%lx is not compatible with PIE",
+ sec->name, insn->offset);
+ }
+ warnings++;
+ break;
+ default:
+ WARN("unexpected relocation type %d at %s+0x%lx",
+ reloc->type, sec->name, reloc->offset);
+ warnings++;
+ break;
+ }
+ }
+ }
+
+ return warnings;
+}
+
int check(struct objtool_file *file)
{
int ret, warnings = 0;
@@ -4673,6 +4749,12 @@ int check(struct objtool_file *file)
warnings += ret;
}
+ if (opts.pie) {
+ ret = validate_pie(file);
+ if (ret < 0)
+ return ret;
+ warnings += ret;
+ }
if (opts.stats) {
printf("nr_insns_visited: %ld\n", nr_insns_visited);
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 2a108e648b7a..1151211a5cea 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -26,6 +26,7 @@ struct opts {
bool uaccess;
int prefix;
bool cfi;
+ bool pie;
/* options: */
bool backtrace;
--
2.31.1
Le 28/04/2023 à 11:51, Hou Wenlong a écrit :
> [Vous ne recevez pas souvent de courriers de houwenlong.hwl@antgroup.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>
> For x86 PIE binary, only RIP-relative addressing is allowed, however,
> there are still a little absolute references of R_X86_64_64 relocation
> type for data section and a little absolute references of R_X86_64_32S
> relocation type in pvh_start_xen() function.
>
> Suggested-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
> Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
> Cc: Thomas Garnier <thgarnie@chromium.org>
> Cc: Kees Cook <keescook@chromium.org>
> ---
> arch/x86/Kconfig | 1 +
> scripts/Makefile.lib | 1 +
> tools/objtool/builtin-check.c | 4 +-
> tools/objtool/check.c | 82 +++++++++++++++++++++++++
> tools/objtool/include/objtool/builtin.h | 1 +
> 5 files changed, 88 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 715f0734d065..b753a54e5ea7 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2224,6 +2224,7 @@ config RELOCATABLE
> config X86_PIE
> def_bool n
> depends on X86_64
> + select OBJTOOL if HAVE_OBJTOOL
>
> config RANDOMIZE_BASE
> bool "Randomize the address of the kernel image (KASLR)"
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 100a386fcd71..e3c804fbc421 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -270,6 +270,7 @@ objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE) += --static-call
> objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION) += --uaccess
> objtool-args-$(CONFIG_GCOV_KERNEL) += --no-unreachable
> objtool-args-$(CONFIG_PREFIX_SYMBOLS) += --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
> +objtool-args-$(CONFIG_X86_PIE) += --pie
>
> objtool-args = $(objtool-args-y) \
> $(if $(delay-objtool), --link) \
> diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
> index 7c175198d09f..1cf1d00464e0 100644
> --- a/tools/objtool/builtin-check.c
> +++ b/tools/objtool/builtin-check.c
> @@ -81,6 +81,7 @@ static const struct option check_options[] = {
> OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"),
> OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
> OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
> + OPT_BOOLEAN(0, "pie", &opts.pie, "validate addressing rules for PIE"),
> OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
>
> OPT_GROUP("Options:"),
> @@ -137,7 +138,8 @@ static bool opts_valid(void)
> opts.sls ||
> opts.stackval ||
> opts.static_call ||
> - opts.uaccess) {
> + opts.uaccess ||
> + opts.pie) {
> if (opts.dump_orc) {
> ERROR("--dump can't be combined with other options");
> return false;
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 5b600bbf2389..d67b80251eec 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -131,6 +131,27 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
> for (insn = next_insn_same_sec(file, insn); insn; \
> insn = next_insn_same_sec(file, insn))
>
> +static struct instruction *find_insn_containing(struct objtool_file *file,
> + struct section *sec,
> + unsigned long offset)
> +{
> + struct instruction *insn;
> +
> + insn = find_insn(file, sec, 0);
> + if (!insn)
> + return NULL;
> +
> + sec_for_each_insn_from(file, insn) {
> + if (insn->offset > offset)
> + return NULL;
> + if (insn->offset <= offset && (insn->offset + insn->len) > offset)
> + return insn;
> + }
> +
> + return NULL;
> +}
> +
> +
> static inline struct symbol *insn_call_dest(struct instruction *insn)
> {
> if (insn->type == INSN_JUMP_DYNAMIC ||
> @@ -4529,6 +4550,61 @@ static int validate_reachable_instructions(struct objtool_file *file)
> return 0;
> }
>
> +static int is_in_pvh_code(struct instruction *insn)
> +{
> + struct symbol *sym = insn->sym;
> +
> + return sym && !strcmp(sym->name, "pvh_start_xen");
> +}
> +
> +static int validate_pie(struct objtool_file *file)
> +{
> + struct section *sec;
> + struct reloc *reloc;
> + struct instruction *insn;
> + int warnings = 0;
> +
> + for_each_sec(file, sec) {
> + if (!sec->reloc)
> + continue;
> + if (!(sec->sh.sh_flags & SHF_ALLOC))
> + continue;
> +
> + list_for_each_entry(reloc, &sec->reloc->reloc_list, list) {
> + switch (reloc->type) {
> + case R_X86_64_NONE:
> + case R_X86_64_PC32:
> + case R_X86_64_PLT32:
> + case R_X86_64_64:
> + case R_X86_64_PC64:
> + case R_X86_64_GOTPCREL:
> + break;
> + case R_X86_64_32:
> + case R_X86_64_32S:
That looks very specific to X86, should it go at another place ?
If it can work for any architecture, can you add generic macros, just
like commit c1449735211d ("objtool: Use macros to define arch specific
reloc types") then commit c984aef8c832 ("objtool/powerpc: Add --mcount
specific implementation") ?
> + insn = find_insn_containing(file, sec, reloc->offset);
> + if (!insn) {
> + WARN("can't find relocate insn near %s+0x%lx",
> + sec->name, reloc->offset);
> + } else {
> + if (is_in_pvh_code(insn))
> + break;
> + WARN("insn at %s+0x%lx is not compatible with PIE",
> + sec->name, insn->offset);
> + }
> + warnings++;
> + break;
> + default:
> + WARN("unexpected relocation type %d at %s+0x%lx",
> + reloc->type, sec->name, reloc->offset);
> + warnings++;
> + break;
> + }
> + }
> + }
> +
> + return warnings;
> +}
> +
> int check(struct objtool_file *file)
> {
> int ret, warnings = 0;
> @@ -4673,6 +4749,12 @@ int check(struct objtool_file *file)
> warnings += ret;
> }
>
> + if (opts.pie) {
> + ret = validate_pie(file);
> + if (ret < 0)
> + return ret;
> + warnings += ret;
> + }
>
> if (opts.stats) {
> printf("nr_insns_visited: %ld\n", nr_insns_visited);
> diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
> index 2a108e648b7a..1151211a5cea 100644
> --- a/tools/objtool/include/objtool/builtin.h
> +++ b/tools/objtool/include/objtool/builtin.h
> @@ -26,6 +26,7 @@ struct opts {
> bool uaccess;
> int prefix;
> bool cfi;
> + bool pie;
>
> /* options: */
> bool backtrace;
> --
> 2.31.1
>
On Fri, Apr 28, 2023 at 06:28:19PM +0800, Christophe Leroy wrote:
>
>
> Le 28/04/2023 à 11:51, Hou Wenlong a écrit :
> > [Vous ne recevez pas souvent de courriers de houwenlong.hwl@antgroup.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> >
> > For x86 PIE binary, only RIP-relative addressing is allowed, however,
> > there are still a little absolute references of R_X86_64_64 relocation
> > type for data section and a little absolute references of R_X86_64_32S
> > relocation type in pvh_start_xen() function.
> >
> > Suggested-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
> > Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
> > Cc: Thomas Garnier <thgarnie@chromium.org>
> > Cc: Kees Cook <keescook@chromium.org>
> > ---
> > arch/x86/Kconfig | 1 +
> > scripts/Makefile.lib | 1 +
> > tools/objtool/builtin-check.c | 4 +-
> > tools/objtool/check.c | 82 +++++++++++++++++++++++++
> > tools/objtool/include/objtool/builtin.h | 1 +
> > 5 files changed, 88 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 715f0734d065..b753a54e5ea7 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -2224,6 +2224,7 @@ config RELOCATABLE
> > config X86_PIE
> > def_bool n
> > depends on X86_64
> > + select OBJTOOL if HAVE_OBJTOOL
> >
> > config RANDOMIZE_BASE
> > bool "Randomize the address of the kernel image (KASLR)"
> > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> > index 100a386fcd71..e3c804fbc421 100644
> > --- a/scripts/Makefile.lib
> > +++ b/scripts/Makefile.lib
> > @@ -270,6 +270,7 @@ objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE) += --static-call
> > objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION) += --uaccess
> > objtool-args-$(CONFIG_GCOV_KERNEL) += --no-unreachable
> > objtool-args-$(CONFIG_PREFIX_SYMBOLS) += --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
> > +objtool-args-$(CONFIG_X86_PIE) += --pie
> >
> > objtool-args = $(objtool-args-y) \
> > $(if $(delay-objtool), --link) \
> > diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
> > index 7c175198d09f..1cf1d00464e0 100644
> > --- a/tools/objtool/builtin-check.c
> > +++ b/tools/objtool/builtin-check.c
> > @@ -81,6 +81,7 @@ static const struct option check_options[] = {
> > OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"),
> > OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
> > OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
> > + OPT_BOOLEAN(0, "pie", &opts.pie, "validate addressing rules for PIE"),
> > OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
> >
> > OPT_GROUP("Options:"),
> > @@ -137,7 +138,8 @@ static bool opts_valid(void)
> > opts.sls ||
> > opts.stackval ||
> > opts.static_call ||
> > - opts.uaccess) {
> > + opts.uaccess ||
> > + opts.pie) {
> > if (opts.dump_orc) {
> > ERROR("--dump can't be combined with other options");
> > return false;
> > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > index 5b600bbf2389..d67b80251eec 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -131,6 +131,27 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
> > for (insn = next_insn_same_sec(file, insn); insn; \
> > insn = next_insn_same_sec(file, insn))
> >
> > +static struct instruction *find_insn_containing(struct objtool_file *file,
> > + struct section *sec,
> > + unsigned long offset)
> > +{
> > + struct instruction *insn;
> > +
> > + insn = find_insn(file, sec, 0);
> > + if (!insn)
> > + return NULL;
> > +
> > + sec_for_each_insn_from(file, insn) {
> > + if (insn->offset > offset)
> > + return NULL;
> > + if (insn->offset <= offset && (insn->offset + insn->len) > offset)
> > + return insn;
> > + }
> > +
> > + return NULL;
> > +}
> > +
> > +
> > static inline struct symbol *insn_call_dest(struct instruction *insn)
> > {
> > if (insn->type == INSN_JUMP_DYNAMIC ||
> > @@ -4529,6 +4550,61 @@ static int validate_reachable_instructions(struct objtool_file *file)
> > return 0;
> > }
> >
> > +static int is_in_pvh_code(struct instruction *insn)
> > +{
> > + struct symbol *sym = insn->sym;
> > +
> > + return sym && !strcmp(sym->name, "pvh_start_xen");
> > +}
> > +
> > +static int validate_pie(struct objtool_file *file)
> > +{
> > + struct section *sec;
> > + struct reloc *reloc;
> > + struct instruction *insn;
> > + int warnings = 0;
> > +
> > + for_each_sec(file, sec) {
> > + if (!sec->reloc)
> > + continue;
> > + if (!(sec->sh.sh_flags & SHF_ALLOC))
> > + continue;
> > +
> > + list_for_each_entry(reloc, &sec->reloc->reloc_list, list) {
> > + switch (reloc->type) {
> > + case R_X86_64_NONE:
> > + case R_X86_64_PC32:
> > + case R_X86_64_PLT32:
> > + case R_X86_64_64:
> > + case R_X86_64_PC64:
> > + case R_X86_64_GOTPCREL:
> > + break;
> > + case R_X86_64_32:
> > + case R_X86_64_32S:
>
> That looks very specific to X86, should it go at another place ?
>
> If it can work for any architecture, can you add generic macros, just
> like commit c1449735211d ("objtool: Use macros to define arch specific
> reloc types") then commit c984aef8c832 ("objtool/powerpc: Add --mcount
> specific implementation") ?
>
Get it, I'll refactor it and move code into X86 directory.
Thanks.
> > + insn = find_insn_containing(file, sec, reloc->offset);
> > + if (!insn) {
> > + WARN("can't find relocate insn near %s+0x%lx",
> > + sec->name, reloc->offset);
> > + } else {
> > + if (is_in_pvh_code(insn))
> > + break;
> > + WARN("insn at %s+0x%lx is not compatible with PIE",
> > + sec->name, insn->offset);
> > + }
> > + warnings++;
> > + break;
> > + default:
> > + WARN("unexpected relocation type %d at %s+0x%lx",
> > + reloc->type, sec->name, reloc->offset);
> > + warnings++;
> > + break;
> > + }
> > + }
> > + }
> > +
> > + return warnings;
> > +}
> > +
> > int check(struct objtool_file *file)
> > {
> > int ret, warnings = 0;
> > @@ -4673,6 +4749,12 @@ int check(struct objtool_file *file)
> > warnings += ret;
> > }
> >
> > + if (opts.pie) {
> > + ret = validate_pie(file);
> > + if (ret < 0)
> > + return ret;
> > + warnings += ret;
> > + }
> >
> > if (opts.stats) {
> > printf("nr_insns_visited: %ld\n", nr_insns_visited);
> > diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
> > index 2a108e648b7a..1151211a5cea 100644
> > --- a/tools/objtool/include/objtool/builtin.h
> > +++ b/tools/objtool/include/objtool/builtin.h
> > @@ -26,6 +26,7 @@ struct opts {
> > bool uaccess;
> > int prefix;
> > bool cfi;
> > + bool pie;
> >
> > /* options: */
> > bool backtrace;
> > --
> > 2.31.1
> >
On Fri, Apr 28, 2023 at 10:28:19AM +0000, Christophe Leroy wrote:
> > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > index 5b600bbf2389..d67b80251eec 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -131,6 +131,27 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
> > for (insn = next_insn_same_sec(file, insn); insn; \
> > insn = next_insn_same_sec(file, insn))
> >
> > +static struct instruction *find_insn_containing(struct objtool_file *file,
> > + struct section *sec,
> > + unsigned long offset)
> > +{
> > + struct instruction *insn;
> > +
> > + insn = find_insn(file, sec, 0);
> > + if (!insn)
> > + return NULL;
> > +
> > + sec_for_each_insn_from(file, insn) {
> > + if (insn->offset > offset)
> > + return NULL;
> > + if (insn->offset <= offset && (insn->offset + insn->len) > offset)
> > + return insn;
> > + }
> > +
> > + return NULL;
> > +}
Urgh, this is horrendous crap. Yes you're only using it in case of a
warning, but adding a function like this makes it appear like it's
actually sane to use.
A far better implementation -- but still not stellar -- would be
something like:
sym = find_symbol_containing(sec, offset);
if (!sym)
// fail
sym_for_each_insn(file, sym, insn) {
...
}
But given insn_hash uses sec_offset_hash() you can do something similar
to find_reloc_by_dest_range()
start = offset - (INSN_MAX_SIZE - 1);
for_offset_range(o, start, start + INSN_MAX_SIZE) {
hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, o)) {
if (insn->sec != sec)
continue;
if (insn->offset <= offset &&
insn->offset + inns->len > offset)
return insn;
}
}
return NULL;
> > +
> > +
> > static inline struct symbol *insn_call_dest(struct instruction *insn)
> > {
> > if (insn->type == INSN_JUMP_DYNAMIC ||
> > @@ -4529,6 +4550,61 @@ static int validate_reachable_instructions(struct objtool_file *file)
> > return 0;
> > }
> >
> > +static int is_in_pvh_code(struct instruction *insn)
> > +{
> > + struct symbol *sym = insn->sym;
> > +
> > + return sym && !strcmp(sym->name, "pvh_start_xen");
> > +}
> > +
> > +static int validate_pie(struct objtool_file *file)
> > +{
> > + struct section *sec;
> > + struct reloc *reloc;
> > + struct instruction *insn;
> > + int warnings = 0;
> > +
> > + for_each_sec(file, sec) {
> > + if (!sec->reloc)
> > + continue;
> > + if (!(sec->sh.sh_flags & SHF_ALLOC))
> > + continue;
> > +
> > + list_for_each_entry(reloc, &sec->reloc->reloc_list, list) {
> > + switch (reloc->type) {
> > + case R_X86_64_NONE:
> > + case R_X86_64_PC32:
> > + case R_X86_64_PLT32:
> > + case R_X86_64_64:
> > + case R_X86_64_PC64:
> > + case R_X86_64_GOTPCREL:
> > + break;
> > + case R_X86_64_32:
> > + case R_X86_64_32S:
>
> That looks very specific to X86, should it go at another place ?
>
> If it can work for any architecture, can you add generic macros, just
> like commit c1449735211d ("objtool: Use macros to define arch specific
> reloc types") then commit c984aef8c832 ("objtool/powerpc: Add --mcount
> specific implementation") ?
Yes, this should be something like arch_PIE_reloc() or so. Similar to
arch_pc_relative_reloc().
On Fri, Apr 28, 2023 at 07:43:38PM +0800, Peter Zijlstra wrote:
> On Fri, Apr 28, 2023 at 10:28:19AM +0000, Christophe Leroy wrote:
>
>
> > > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > > index 5b600bbf2389..d67b80251eec 100644
> > > --- a/tools/objtool/check.c
> > > +++ b/tools/objtool/check.c
> > > @@ -131,6 +131,27 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
> > > for (insn = next_insn_same_sec(file, insn); insn; \
> > > insn = next_insn_same_sec(file, insn))
> > >
> > > +static struct instruction *find_insn_containing(struct objtool_file *file,
> > > + struct section *sec,
> > > + unsigned long offset)
> > > +{
> > > + struct instruction *insn;
> > > +
> > > + insn = find_insn(file, sec, 0);
> > > + if (!insn)
> > > + return NULL;
> > > +
> > > + sec_for_each_insn_from(file, insn) {
> > > + if (insn->offset > offset)
> > > + return NULL;
> > > + if (insn->offset <= offset && (insn->offset + insn->len) > offset)
> > > + return insn;
> > > + }
> > > +
> > > + return NULL;
> > > +}
>
> Urgh, this is horrendous crap. Yes you're only using it in case of a
> warning, but adding a function like this makes it appear like it's
> actually sane to use.
>
> A far better implementation -- but still not stellar -- would be
> something like:
>
> sym = find_symbol_containing(sec, offset);
> if (!sym)
> // fail
> sym_for_each_insn(file, sym, insn) {
> ...
> }
>
> But given insn_hash uses sec_offset_hash() you can do something similar
> to find_reloc_by_dest_range()
>
> start = offset - (INSN_MAX_SIZE - 1);
> for_offset_range(o, start, start + INSN_MAX_SIZE) {
> hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, o)) {
> if (insn->sec != sec)
> continue;
>
> if (insn->offset <= offset &&
> insn->offset + inns->len > offset)
> return insn;
> }
> }
> return NULL;
>
Thanks for your suggestion, I'll pick it in the next version.
> > > +
> > > +
> > > static inline struct symbol *insn_call_dest(struct instruction *insn)
> > > {
> > > if (insn->type == INSN_JUMP_DYNAMIC ||
> > > @@ -4529,6 +4550,61 @@ static int validate_reachable_instructions(struct objtool_file *file)
> > > return 0;
> > > }
> > >
> > > +static int is_in_pvh_code(struct instruction *insn)
> > > +{
> > > + struct symbol *sym = insn->sym;
> > > +
> > > + return sym && !strcmp(sym->name, "pvh_start_xen");
> > > +}
> > > +
> > > +static int validate_pie(struct objtool_file *file)
> > > +{
> > > + struct section *sec;
> > > + struct reloc *reloc;
> > > + struct instruction *insn;
> > > + int warnings = 0;
> > > +
> > > + for_each_sec(file, sec) {
> > > + if (!sec->reloc)
> > > + continue;
> > > + if (!(sec->sh.sh_flags & SHF_ALLOC))
> > > + continue;
> > > +
> > > + list_for_each_entry(reloc, &sec->reloc->reloc_list, list) {
> > > + switch (reloc->type) {
> > > + case R_X86_64_NONE:
> > > + case R_X86_64_PC32:
> > > + case R_X86_64_PLT32:
> > > + case R_X86_64_64:
> > > + case R_X86_64_PC64:
> > > + case R_X86_64_GOTPCREL:
> > > + break;
> > > + case R_X86_64_32:
> > > + case R_X86_64_32S:
> >
> > That looks very specific to X86, should it go at another place ?
> >
> > If it can work for any architecture, can you add generic macros, just
> > like commit c1449735211d ("objtool: Use macros to define arch specific
> > reloc types") then commit c984aef8c832 ("objtool/powerpc: Add --mcount
> > specific implementation") ?
>
> Yes, this should be something like arch_PIE_reloc() or so. Similar to
> arch_pc_relative_reloc().
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