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Subject[PATCH v7 3/4] x86/dumpstack: Introduce die_addr() for die() with #GP fault address
From
Split __die() into __die_header() and __die_body(). This allows inserting
extra information below the header line that initiates the bug report.

Introduce a new function die_addr() that behaves like die(), but is for
faults only and uses __die_header()+__die_body() so that a future commit
can print extra information after the header line.

Signed-off-by: Jann Horn <jannh@google.com>
---

Notes:
v3:
new patch
v4-v6:
no changes
v7:
- introduce die_addr() instead of open-coding __die_header()
and __die_body() calls in traps.c (Borislav)
- make __die_header() and __die_body() static
- rewrite commit message

arch/x86/include/asm/kdebug.h | 1 +
arch/x86/kernel/dumpstack.c | 24 +++++++++++++++++++++++-
arch/x86/kernel/traps.c | 5 ++++-
3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h
index 75f1e35e7c15..247ab14c6309 100644
--- a/arch/x86/include/asm/kdebug.h
+++ b/arch/x86/include/asm/kdebug.h
@@ -33,6 +33,7 @@ enum show_regs_mode {
};

extern void die(const char *, struct pt_regs *,long);
+void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr);
extern int __must_check __die(const char *, struct pt_regs *, long);
extern void show_stack_regs(struct pt_regs *regs);
extern void __show_regs(struct pt_regs *regs, enum show_regs_mode);
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index e07424e19274..8995bf10c97c 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -365,7 +365,7 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
}
NOKPROBE_SYMBOL(oops_end);

-int __die(const char *str, struct pt_regs *regs, long err)
+static void __die_header(const char *str, struct pt_regs *regs, long err)
{
const char *pr = "";

@@ -384,7 +384,11 @@ int __die(const char *str, struct pt_regs *regs, long err)
IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
(boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
+}
+NOKPROBE_SYMBOL(__die_header);

+static int __die_body(const char *str, struct pt_regs *regs, long err)
+{
show_regs(regs);
print_modules();

@@ -394,6 +398,13 @@ int __die(const char *str, struct pt_regs *regs, long err)

return 0;
}
+NOKPROBE_SYMBOL(__die_body);
+
+int __die(const char *str, struct pt_regs *regs, long err)
+{
+ __die_header(str, regs, err);
+ return __die_body(str, regs, err);
+}
NOKPROBE_SYMBOL(__die);

/*
@@ -410,6 +421,17 @@ void die(const char *str, struct pt_regs *regs, long err)
oops_end(flags, regs, sig);
}

+void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr)
+{
+ unsigned long flags = oops_begin();
+ int sig = SIGSEGV;
+
+ __die_header(str, regs, err);
+ if (__die_body(str, regs, err))
+ sig = 0;
+ oops_end(flags, regs, sig);
+}
+
void show_regs(struct pt_regs *regs)
{
show_regs_print_info(KERN_DEFAULT);
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index c8b4ae6aed5b..4c691bb9e0d9 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -621,7 +621,10 @@ do_general_protection(struct pt_regs *regs, long error_code)
"maybe for address",
gp_addr);

- die(desc, regs, error_code);
+ if (hint != GP_NON_CANONICAL)
+ gp_addr = 0;
+
+ die_addr(desc, regs, error_code, gp_addr);
return;
}

--
2.24.1.735.g03f4e72817-goog
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