OpenCloudOS-Kernel/arch/powerpc/kernel/ppc_ksyms.c

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#include <linux/ftrace.h>
#include <linux/mm.h>
#include <asm/processor.h>
#include <asm/switch_to.h>
#include <asm/cacheflush.h>
#include <asm/epapr_hcalls.h>
EXPORT_SYMBOL(flush_dcache_range);
EXPORT_SYMBOL(flush_icache_range);
EXPORT_SYMBOL(empty_zero_page);
long long __bswapdi2(long long);
EXPORT_SYMBOL(__bswapdi2);
#ifdef CONFIG_FUNCTION_TRACER
EXPORT_SYMBOL(_mcount);
#endif
#ifdef CONFIG_PPC_FPU
EXPORT_SYMBOL(load_fp_state);
EXPORT_SYMBOL(store_fp_state);
#endif
#ifdef CONFIG_ALTIVEC
EXPORT_SYMBOL(load_vr_state);
EXPORT_SYMBOL(store_vr_state);
#endif
#ifdef CONFIG_VSX
EXPORT_SYMBOL_GPL(__giveup_vsx);
#endif
#ifdef CONFIG_EPAPR_PARAVIRT
EXPORT_SYMBOL(epapr_hypercall_start);
#endif
powerpc: Reimplement __get_SP() as a function not a define Li Zhong points out an issue with our current __get_SP() implementation. If ftrace function tracing is enabled (ie -pg profiling using _mcount) we spill a stack frame on 64bit all the time. If a function calls __get_SP() and later calls a function that is tail call optimised, we will pop the stack frame and the value returned by __get_SP() is no longer valid. An example from Li can be found in save_stack_trace -> save_context_stack: c0000000000432c0 <.save_stack_trace>: c0000000000432c0: mflr r0 c0000000000432c4: std r0,16(r1) c0000000000432c8: stdu r1,-128(r1) <-- stack frame for _mcount c0000000000432cc: std r3,112(r1) c0000000000432d0: bl <._mcount> c0000000000432d4: nop c0000000000432d8: mr r4,r1 <-- __get_SP() c0000000000432dc: ld r5,632(r13) c0000000000432e0: ld r3,112(r1) c0000000000432e4: li r6,1 c0000000000432e8: addi r1,r1,128 <-- pop stack frame c0000000000432ec: ld r0,16(r1) c0000000000432f0: mtlr r0 c0000000000432f4: b <.save_context_stack> <-- tail call optimized save_context_stack ends up with a stack pointer below the current one, and it is likely to be scribbled over. Fix this by making __get_SP() a function which returns the callers stack frame. Also replace inline assembly which grabs the stack pointer in save_stack_trace and show_stack with __get_SP(). This also fixes an issue with perf_arch_fetch_caller_regs(). It currently unwinds the stack once, which will skip a valid stack frame on a leaf function. With the __get_SP() fixes in this patch, we never need to unwind the stack frame to get to the first interesting frame. We have to export __get_SP() because perf_arch_fetch_caller_regs() (which is used in modules) calls it from a header file. Reported-by: Li Zhong <zhong@linux.vnet.ibm.com> Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2014-10-13 16:41:38 +08:00
EXPORT_SYMBOL(current_stack_pointer);