linux-kernel - [PATCH] perf: perf can not parser the backtrace of app with dwarf mode in the 32bit system and 64bit kernel.

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Date:   Thu, 7 May 2020 09:04:08 +0800
From:   Jiping Ma <jiping.ma2@...driver.com>
To:     <will.deacon@....com>, <mark.rutland@....com>,
        <catalin.marinas@....com>, <jiping.ma2@...driver.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] perf: perf can not parser the backtrace of app with dwarf mode in the 32bit system and 64bit kernel.

Record PC value from regs[15], it should be regs[32] in REGS_ABI_32 mode,
which cause perf parser the backtrace failed.

Signed-off-by: Jiping Ma <jiping.ma2@...driver.com>
---
 arch/arm64/kernel/perf_regs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kernel/perf_regs.c b/arch/arm64/kernel/perf_regs.c
index 0bbac61..04088e6 100644
--- a/arch/arm64/kernel/perf_regs.c
+++ b/arch/arm64/kernel/perf_regs.c
@@ -32,6 +32,10 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
 	if ((u32)idx == PERF_REG_ARM64_PC)
 		return regs->pc;
 
+	if (perf_reg_abi(current) == PERF_SAMPLE_REGS_ABI_32
+		&& idx == 15)
+		return regs->regs[PERF_REG_ARM64_PC];
+
 	return regs->regs[idx];
 }
 
-- 
1.9.1