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Bug 25050: X87 FPU Special Purpose Registers

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Summary:
  - For x86_64-FreeBSD Platform:
    -- LLDB now provides correct values of X87 FPU
       Special Purpose Registers like fstat, ftag, fctrl etc..

Signed-off-by: Abhishek Aggarwal <abhishek.a.aggarwal@intel.com>

Reviewers: emaste, mikesart, clayborg

Subscribers: emaste

Differential Revision: http://reviews.llvm.org/D13434

llvm-svn: 249379
This commit is contained in:
Abhishek Aggarwal
2015-10-06 07:04:03 +00:00
parent 2c4068f409
commit 2f00005cd7
2 changed files with 22 additions and 4 deletions
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25
lldb/source/Plugins/Process/FreeBSD/RegisterContextPOSIXProcessMonitor_x86.cpp
View File

@@ -58,6 +58,9 @@ RegisterContextPOSIXProcessMonitor_x86_64::RegisterContextPOSIXProcessMonitor_x8
lldb_private::RegisterInfoInterface *register_info)
: RegisterContextPOSIX_x86(thread, concrete_frame_idx, register_info)
{
// Store byte offset of fctrl (i.e. first register of FPR) wrt 'UserArea'
const RegisterInfo *reg_info_fctrl = GetRegisterInfoByName("fctrl");
m_fctrl_offset_in_userarea = reg_info_fctrl->byte_offset;
}
ProcessMonitor &
@@ -254,8 +257,15 @@ RegisterContextPOSIXProcessMonitor_x86_64::ReadRegister(const RegisterInfo *reg_
}
// Get pointer to m_fpr.xstate.fxsave variable and set the data from it.
assert (reg_info->byte_offset < sizeof(m_fpr));
uint8_t *src = (uint8_t *)&m_fpr + reg_info->byte_offset;
// Byte offsets of all registers are calculated wrt 'UserArea' structure.
// However, ReadFPR() reads fpu registers {using ptrace(PT_GETFPREGS,..)}
// and stores them in 'm_fpr' (of type FPR structure). To extract values of fpu
// registers, m_fpr should be read at byte offsets calculated wrt to FPR structure.
// Since, FPR structure is also one of the member of UserArea structure.
// byte_offset(fpu wrt FPR) = byte_offset(fpu wrt UserArea) - byte_offset(fctrl wrt UserArea)
assert ( (reg_info->byte_offset - m_fctrl_offset_in_userarea) < sizeof(m_fpr));
uint8_t *src = (uint8_t *)&m_fpr + reg_info->byte_offset - m_fctrl_offset_in_userarea;
switch (reg_info->byte_size)
{
case 2:
@@ -308,8 +318,15 @@ RegisterContextPOSIXProcessMonitor_x86_64::WriteRegister(const RegisterInfo *reg
else
{
// Get pointer to m_fpr.xstate.fxsave variable and set the data to it.
assert (reg_info->byte_offset < sizeof(m_fpr));
uint8_t *dst = (uint8_t *)&m_fpr + reg_info->byte_offset;
// Byte offsets of all registers are calculated wrt 'UserArea' structure.
// However, WriteFPR() takes m_fpr (of type FPR structure) and writes only fpu
// registers using ptrace(PT_SETFPREGS,..) API. Hence fpu registers should
// be written in m_fpr at byte offsets calculated wrt FPR structure.
// Since, FPR structure is also one of the member of UserArea structure.
// byte_offset(fpu wrt FPR) = byte_offset(fpu wrt UserArea) - byte_offset(fctrl wrt UserArea)
assert ( (reg_info->byte_offset - m_fctrl_offset_in_userarea) < sizeof(m_fpr));
uint8_t *dst = (uint8_t *)&m_fpr + reg_info->byte_offset - m_fctrl_offset_in_userarea;
switch (reg_info->byte_size)
{
case 2:

1
lldb/source/Plugins/Process/FreeBSD/RegisterContextPOSIXProcessMonitor_x86.h
View File

@@ -91,6 +91,7 @@ protected:
private:
ProcessMonitor &
GetMonitor();
uint32_t m_fctrl_offset_in_userarea; // Offset of 'fctrl' in 'UserArea' Structure
};
#endif