From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Michael Neuling To: Benjamin Herrenschmidt Subject: [PATCH 2/2] powerpc/perf: Fix setting of "to" addresses for BHRB Date: Thu, 9 May 2013 11:46:49 +1000 Message-Id: <1368064009-13255-2-git-send-email-mikey@neuling.org> In-Reply-To: <1368064009-13255-1-git-send-email-mikey@neuling.org> References: <1368064009-13255-1-git-send-email-mikey@neuling.org> Cc: Michael Neuling , linuxppc-dev@lists.ozlabs.org, Anshuman Khandual List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Currently we only set the "to" address in the branch stack when the CPU explicitly gives us a value. Unfortunately it only does this for XL form branches (eg blr, bctr, bctar) and not I and B form branches (eg b, bc). Fortunately if we read the instruction from memory we can extract the offset of a branch and calculate the target address. This adds a function power_pmu_bhrb_to() to calculate the target/to address of the corresponding I and B form branches. It handles branches in both user and kernel spaces. It also plumbs this into the perf brhb reading code. Signed-off-by: Michael Neuling --- arch/powerpc/perf/core-book3s.c | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 2d81372..37f652f 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -13,11 +13,13 @@ #include #include #include +#include #include #include #include #include #include +#include #define BHRB_MAX_ENTRIES 32 #define BHRB_TARGET 0x0000000000000002 @@ -1458,6 +1460,33 @@ struct pmu power_pmu = { .flush_branch_stack = power_pmu_flush_branch_stack, }; +/* Calculate the to address for a branch */ +static __u64 power_pmu_bhrb_to(u64 addr) +{ + unsigned int instr; + int ret; + __u64 target; + + if (is_kernel_addr(addr)) + return branch_target((unsigned int *)addr); + + /* Userspace: need copy instruction here then translate it */ + pagefault_disable(); + ret = __get_user_inatomic(instr, (unsigned int *)addr); + if (ret) { + pagefault_enable(); + return 0; + } + pagefault_enable(); + + target = branch_target(&instr); + if ((!target) || (instr & BRANCH_ABSOLUTE)) + return target; + + /* Translate relative branch target from kernel to user address */ + return target - (unsigned long)&instr + addr; +} + /* Processing BHRB entries */ void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw) { @@ -1521,7 +1550,8 @@ void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw) /* Branches to immediate field (ie I or B form) */ cpuhw->bhrb_entries[u_index].from = addr; - cpuhw->bhrb_entries[u_index].to = 0; + cpuhw->bhrb_entries[u_index].to = + power_pmu_bhrb_to(addr); cpuhw->bhrb_entries[u_index].mispred = pred; cpuhw->bhrb_entries[u_index].predicted = ~pred; } -- 1.7.10.4