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Message-Id: <1427831308-1854-138-git-send-email-kamal@canonical.com> Date: Tue, 31 Mar 2015 12:48:22 -0700 From: Kamal Mostafa <kamal@...onical.com> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org, kernel-team@...ts.ubuntu.com Cc: James Hogan <james.hogan@...tec.com>, linux-metag@...r.kernel.org, Kamal Mostafa <kamal@...onical.com> Subject: [PATCH 3.13.y-ckt 137/143] metag: Fix KSTK_EIP() and KSTK_ESP() macros 3.13.11-ckt18 -stable review patch. If anyone has any objections, please let me know. ------------------ From: James Hogan <james.hogan@...tec.com> commit c2996cb29bfb73927a79dc96e598a718e843f01a upstream. The KSTK_EIP() and KSTK_ESP() macros should return the user program counter (PC) and stack pointer (A0StP) of the given task. These are used to determine which VMA corresponds to the user stack in /proc/<pid>/maps, and for the user PC & A0StP in /proc/<pid>/stat. However for Meta the PC & A0StP from the task's kernel context are used, resulting in broken output. For example in following /proc/<pid>/maps output, the 3afff000-3b021000 VMA should be described as the stack: # cat /proc/self/maps ... 100b0000-100b1000 rwxp 00000000 00:00 0 [heap] 3afff000-3b021000 rwxp 00000000 00:00 0 And in the following /proc/<pid>/stat output, the PC is in kernel code (1074234964 = 0x40078654) and the A0StP is in the kernel heap (1335981392 = 0x4fa17550): # cat /proc/self/stat 51 (cat) R ... 1335981392 1074234964 ... Fix the definitions of KSTK_EIP() and KSTK_ESP() to use task_pt_regs(tsk)->ctx rather than (tsk)->thread.kernel_context. This gets the registers from the user context stored after the thread info at the base of the kernel stack, which is from the last entry into the kernel from userland, regardless of where in the kernel the task may have been interrupted, which results in the following more correct /proc/<pid>/maps output: # cat /proc/self/maps ... 0800b000-08070000 r-xp 00000000 00:02 207 /lib/libuClibc-0.9.34-git.so ... 100b0000-100b1000 rwxp 00000000 00:00 0 [heap] 3afff000-3b021000 rwxp 00000000 00:00 0 [stack] And /proc/<pid>/stat now correctly reports the PC in libuClibc (134320308 = 0x80190b4) and the A0StP in the [stack] region (989864576 = 0x3b002280): # cat /proc/self/stat 51 (cat) R ... 989864576 134320308 ... Reported-by: Alexey Brodkin <Alexey.Brodkin@...opsys.com> Reported-by: Vineet Gupta <Vineet.Gupta1@...opsys.com> Signed-off-by: James Hogan <james.hogan@...tec.com> Cc: linux-metag@...r.kernel.org Signed-off-by: Kamal Mostafa <kamal@...onical.com> --- arch/metag/include/asm/processor.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/metag/include/asm/processor.h b/arch/metag/include/asm/processor.h index 3be8581..ba85738 100644 --- a/arch/metag/include/asm/processor.h +++ b/arch/metag/include/asm/processor.h @@ -149,8 +149,8 @@ extern void exit_thread(void); unsigned long get_wchan(struct task_struct *p); -#define KSTK_EIP(tsk) ((tsk)->thread.kernel_context->CurrPC) -#define KSTK_ESP(tsk) ((tsk)->thread.kernel_context->AX[0].U0) +#define KSTK_EIP(tsk) (task_pt_regs(tsk)->ctx.CurrPC) +#define KSTK_ESP(tsk) (task_pt_regs(tsk)->ctx.AX[0].U0) #define user_stack_pointer(regs) ((regs)->ctx.AX[0].U0) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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