[PATCH 3/3] powerpc/kgdb: restore current_thread_info properly
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STALE5176d
From: Tiejun Chen <hidden>
Date: 2012-08-22 10:50:46
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
For powerpc BooKE and e200, singlestep is handled on the critical/dbg exception stack. This causes current_thread_info() to fail for kgdb internal, so previously We work around this issue by copying the thread_info from the kernel stack before calling kgdb_handle_exception, and copying it back afterwards. But actually we don't do this previously. We should backp current_thread_info then restore that when exit. CC: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Tiejun Chen <redacted> --- arch/powerpc/kernel/kgdb.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index e84252b..7dcdbe7 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c@@ -25,6 +25,7 @@ #include <asm/processor.h> #include <asm/machdep.h> #include <asm/debug.h> +#include <linux/slab.h> /* * This table contains the mapping between PowerPC hardware trap types, and
@@ -156,6 +157,8 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs) static int kgdb_singlestep(struct pt_regs *regs) { struct thread_info *thread_info, *exception_thread_info; + struct thread_info *backup_current_thread_info = \ + (struct thread_info *)kmalloc(sizeof(struct thread_info), GFP_KERNEL); if (user_mode(regs)) return 0;
@@ -173,13 +176,17 @@ static int kgdb_singlestep(struct pt_regs *regs) thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1)); exception_thread_info = current_thread_info(); - if (thread_info != exception_thread_info) + if (thread_info != exception_thread_info) { + /* Save the original current_thread_info. */ + memcpy(backup_current_thread_info, exception_thread_info, sizeof *thread_info); memcpy(exception_thread_info, thread_info, sizeof *thread_info); + } kgdb_handle_exception(0, SIGTRAP, 0, regs); if (thread_info != exception_thread_info) - memcpy(thread_info, exception_thread_info, sizeof *thread_info); + /* Restore current_thread_info lastly. */ + memcpy(exception_thread_info, backup_current_thread_info, sizeof *thread_info); return 1; }
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1.5.6